diff --git a/tests/_support/Commands/AppInfo.php b/tests/_support/Commands/AppInfo.php
index e7bf3093e658..efb6d941a953 100644
--- a/tests/_support/Commands/AppInfo.php
+++ b/tests/_support/Commands/AppInfo.php
@@ -23,12 +23,12 @@ class AppInfo extends BaseCommand
     protected $arguments   = ['draft' => 'unused'];
     protected $description = 'Displays basic application information.';
 
-    public function run(array $params)
+    public function run(array $params): void
     {
         CLI::write('CI Version: ' . CLI::color(CodeIgniter::CI_VERSION, 'red'));
     }
 
-    public function bomb()
+    public function bomb(): void
     {
         try {
             CLI::color('test', 'white', 'Background');
@@ -37,7 +37,7 @@ public function bomb()
         }
     }
 
-    public function helpme()
+    public function helpme(): void
     {
         $this->call('help');
     }
diff --git a/tests/_support/Commands/InvalidCommand.php b/tests/_support/Commands/InvalidCommand.php
index 5b4acf936b08..e69827669290 100644
--- a/tests/_support/Commands/InvalidCommand.php
+++ b/tests/_support/Commands/InvalidCommand.php
@@ -27,7 +27,7 @@ public function __construct()
         throw new ReflectionException();
     }
 
-    public function run(array $params)
+    public function run(array $params): void
     {
         CLI::write('CI Version: ' . CLI::color(CodeIgniter::CI_VERSION, 'red'));
     }
diff --git a/tests/_support/Commands/LanguageCommand.php b/tests/_support/Commands/LanguageCommand.php
index e495d250a295..978099e5257f 100644
--- a/tests/_support/Commands/LanguageCommand.php
+++ b/tests/_support/Commands/LanguageCommand.php
@@ -27,7 +27,7 @@ class LanguageCommand extends BaseCommand
         '--sort' => 'Turn on/off the sortImports flag.',
     ];
 
-    public function run(array $params)
+    public function run(array $params): void
     {
         $this->setHasClassName(false);
         $params[0] = 'Foobar';
diff --git a/tests/_support/Commands/ParamsReveal.php b/tests/_support/Commands/ParamsReveal.php
index 76be444e69d1..331c1471611f 100644
--- a/tests/_support/Commands/ParamsReveal.php
+++ b/tests/_support/Commands/ParamsReveal.php
@@ -21,7 +21,7 @@ class ParamsReveal extends BaseCommand
     protected $description = 'Reveal params';
     public static $args;
 
-    public function run(array $params)
+    public function run(array $params): void
     {
         static::$args = $params;
     }
diff --git a/tests/_support/Commands/Unsuffixable.php b/tests/_support/Commands/Unsuffixable.php
index 36a752e25891..cf906071d7ef 100644
--- a/tests/_support/Commands/Unsuffixable.php
+++ b/tests/_support/Commands/Unsuffixable.php
@@ -65,7 +65,7 @@ class Unsuffixable extends BaseCommand
     /**
      * Actually execute a command.
      */
-    public function run(array $params)
+    public function run(array $params): void
     {
         $this->component = 'Command';
         $this->directory = 'Commands';
diff --git a/tests/_support/Controllers/Popcorn.php b/tests/_support/Controllers/Popcorn.php
index 660a405cccc2..2084c3b81713 100644
--- a/tests/_support/Controllers/Popcorn.php
+++ b/tests/_support/Controllers/Popcorn.php
@@ -33,7 +33,7 @@ public function pop()
         return $this->respond('Oops', 567, 'Surprise');
     }
 
-    public function popper()
+    public function popper(): void
     {
         throw new RuntimeException('Surprise', 500);
     }
@@ -61,12 +61,12 @@ public function index3()
         return $this->response->setJSON(['lang' => $this->request->getLocale()]);
     }
 
-    public function canyon()
+    public function canyon(): void
     {
         echo 'Hello-o-o ' . $this->request->getGet('foo');
     }
 
-    public function cat()
+    public function cat(): void
     {
     }
 
diff --git a/tests/_support/Database/Migrations/20160428212500_Create_test_tables.php b/tests/_support/Database/Migrations/20160428212500_Create_test_tables.php
index ac489ecbb57b..6e3d9be574fa 100644
--- a/tests/_support/Database/Migrations/20160428212500_Create_test_tables.php
+++ b/tests/_support/Database/Migrations/20160428212500_Create_test_tables.php
@@ -15,7 +15,7 @@
 
 class Migration_Create_test_tables extends Migration
 {
-    public function up()
+    public function up(): void
     {
         // User Table
         $this->forge->addField([
@@ -160,7 +160,7 @@ public function up()
         }
     }
 
-    public function down()
+    public function down(): void
     {
         $this->forge->dropTable('user', true);
         $this->forge->dropTable('job', true);
diff --git a/tests/_support/Database/Seeds/AnotherSeeder.php b/tests/_support/Database/Seeds/AnotherSeeder.php
index aaf7c7e93410..09c9a93d8af8 100644
--- a/tests/_support/Database/Seeds/AnotherSeeder.php
+++ b/tests/_support/Database/Seeds/AnotherSeeder.php
@@ -15,7 +15,7 @@
 
 class AnotherSeeder extends Seeder
 {
-    public function run()
+    public function run(): void
     {
         $row = [
             'name'    => 'Jerome Lohan',
diff --git a/tests/_support/Database/Seeds/CITestSeeder.php b/tests/_support/Database/Seeds/CITestSeeder.php
index 9353578246b5..1749970fe338 100644
--- a/tests/_support/Database/Seeds/CITestSeeder.php
+++ b/tests/_support/Database/Seeds/CITestSeeder.php
@@ -15,7 +15,7 @@
 
 class CITestSeeder extends Seeder
 {
-    public function run()
+    public function run(): void
     {
         // Job Data
         $data = [
diff --git a/tests/_support/Filters/Customfilter.php b/tests/_support/Filters/Customfilter.php
index 7efbb6c0ddb8..6804cacf62b4 100644
--- a/tests/_support/Filters/Customfilter.php
+++ b/tests/_support/Filters/Customfilter.php
@@ -23,7 +23,7 @@ public function before(RequestInterface $request, $arguments = null)
         return $request;
     }
 
-    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null): void
     {
     }
 }
diff --git a/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102301_Some_migration.php b/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102301_Some_migration.php
index 39eb6e0879cc..e0a34f3eb03c 100644
--- a/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102301_Some_migration.php
+++ b/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102301_Some_migration.php
@@ -13,7 +13,7 @@
 
 class Migration_some_migration extends \CodeIgniter\Database\Migration
 {
-    public function up()
+    public function up(): void
     {
         $this->forge->addField([
             'key' => [
@@ -28,7 +28,7 @@ public function up()
         ]);
     }
 
-    public function down()
+    public function down(): void
     {
         $this->forge->dropTable('foo', true);
     }
diff --git a/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102302_Another_migration.php b/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102302_Another_migration.php
index f1606eff56e1..0006da2a347d 100644
--- a/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102302_Another_migration.php
+++ b/tests/_support/MigrationTestMigrations/Database/Migrations/2018-01-24-102302_Another_migration.php
@@ -13,7 +13,7 @@
 
 class Migration_another_migration extends \CodeIgniter\Database\Migration
 {
-    public function up()
+    public function up(): void
     {
         $fields = [
             'value' => [
@@ -29,7 +29,7 @@ public function up()
         ]);
     }
 
-    public function down()
+    public function down(): void
     {
         if ($this->db->tableExists('foo')) {
             $this->forge->dropColumn('foo', 'value');
diff --git a/tests/_support/Publishers/TestPublisher.php b/tests/_support/Publishers/TestPublisher.php
index 95d9fa72c250..0e3b67ab23a5 100644
--- a/tests/_support/Publishers/TestPublisher.php
+++ b/tests/_support/Publishers/TestPublisher.php
@@ -39,7 +39,7 @@ final class TestPublisher extends Publisher
     /**
      * Fakes an error on the given file.
      */
-    public static function setResult(bool $result)
+    public static function setResult(bool $result): void
     {
         self::$result = $result;
     }
diff --git a/tests/_support/View/Cells/AdditionCell.php b/tests/_support/View/Cells/AdditionCell.php
index aaa89a6560cb..0b5b8a5ddc74 100644
--- a/tests/_support/View/Cells/AdditionCell.php
+++ b/tests/_support/View/Cells/AdditionCell.php
@@ -17,7 +17,7 @@ class AdditionCell extends Cell
 {
     public int $value = 2;
 
-    public function mount(?int $number = null, bool $skipAddition = false)
+    public function mount(?int $number = null, bool $skipAddition = false): void
     {
         $this->value = ! $skipAddition
             ? $this->value + (int) $number
diff --git a/tests/_support/View/SampleClassWithInitController.php b/tests/_support/View/SampleClassWithInitController.php
index 32eb4f70a7a3..8b12326c5b58 100644
--- a/tests/_support/View/SampleClassWithInitController.php
+++ b/tests/_support/View/SampleClassWithInitController.php
@@ -25,7 +25,7 @@ class SampleClassWithInitController
 {
     private ResponseInterface $response;
 
-    public function initController(RequestInterface $request, ResponseInterface $response, LoggerInterface $logger)
+    public function initController(RequestInterface $request, ResponseInterface $response, LoggerInterface $logger): void
     {
         $this->response = $response;
     }
diff --git a/tests/system/API/ResponseTraitTest.php b/tests/system/API/ResponseTraitTest.php
index b8a522da86dd..693eff53f33d 100644
--- a/tests/system/API/ResponseTraitTest.php
+++ b/tests/system/API/ResponseTraitTest.php
@@ -95,14 +95,14 @@ public function __construct(&$request, &$response, &$formatter)
                 $this->formatter = $formatter;
             }
 
-            public function resetFormatter()
+            public function resetFormatter(): void
             {
                 $this->formatter = null;
             }
         };
     }
 
-    public function testNoFormatterJSON()
+    public function testNoFormatterJSON(): void
     {
         $this->formatter = null;
         $controller      = $this->makeController([], 'http://codeigniter.com', ['Accept' => 'application/json']);
@@ -120,7 +120,7 @@ public function testNoFormatterJSON()
         $this->assertSame($expected, $this->response->getBody());
     }
 
-    public function testNoFormatter()
+    public function testNoFormatter(): void
     {
         $this->formatter = null;
         $controller      = $this->makeController([], 'http://codeigniter.com', ['Accept' => 'application/json']);
@@ -130,7 +130,7 @@ public function testNoFormatter()
         $this->assertSame('A Custom Reason', $this->response->getBody());
     }
 
-    public function testAssociativeArrayPayload()
+    public function testAssociativeArrayPayload(): void
     {
         $this->formatter = null;
         $controller      = $this->makeController();
@@ -146,7 +146,7 @@ public function testAssociativeArrayPayload()
         $this->assertSame($expected, $this->response->getBody());
     }
 
-    public function testArrayPayload()
+    public function testArrayPayload(): void
     {
         $this->formatter = null;
         $controller      = $this->makeController();
@@ -168,7 +168,7 @@ public function testArrayPayload()
         $this->assertSame($expected, $this->response->getBody());
     }
 
-    public function testPHPtoArrayPayload()
+    public function testPHPtoArrayPayload(): void
     {
         $this->formatter = null;
         $controller      = $this->makeController();
@@ -187,7 +187,7 @@ public function testPHPtoArrayPayload()
         $this->assertSame($expected, $this->response->getBody());
     }
 
-    public function testRespondSets404WithNoData()
+    public function testRespondSets404WithNoData(): void
     {
         $controller = $this->makeController();
 
@@ -197,7 +197,7 @@ public function testRespondSets404WithNoData()
         $this->assertNull($this->response->getBody());
     }
 
-    public function testRespondSetsStatusWithEmptyData()
+    public function testRespondSetsStatusWithEmptyData(): void
     {
         $controller = $this->makeController();
 
@@ -207,7 +207,7 @@ public function testRespondSetsStatusWithEmptyData()
         $this->assertNull($this->response->getBody());
     }
 
-    public function testRespondSetsCorrectBodyAndStatus()
+    public function testRespondSetsCorrectBodyAndStatus(): void
     {
         $controller = $this->makeController();
 
@@ -219,7 +219,7 @@ public function testRespondSetsCorrectBodyAndStatus()
         $this->assertSame('Created', $this->response->getReason());
     }
 
-    public function testRespondWithCustomReason()
+    public function testRespondWithCustomReason(): void
     {
         $controller = $this->makeController();
 
@@ -229,7 +229,7 @@ public function testRespondWithCustomReason()
         $this->assertSame('A Custom Reason', $this->response->getReason());
     }
 
-    public function testFailSingleMessage()
+    public function testFailSingleMessage(): void
     {
         $controller = $this->makeController();
 
@@ -248,7 +248,7 @@ public function testFailSingleMessage()
         $this->assertSame('A Custom Reason', $this->response->getReason());
     }
 
-    public function testCreated()
+    public function testCreated(): void
     {
         $controller = $this->makeController();
 
@@ -259,7 +259,7 @@ public function testCreated()
         $this->assertSame($this->formatter->format(['id' => 3]), $this->response->getBody());
     }
 
-    public function testDeleted()
+    public function testDeleted(): void
     {
         $controller = $this->makeController();
 
@@ -270,7 +270,7 @@ public function testDeleted()
         $this->assertSame($this->formatter->format(['id' => 3]), $this->response->getBody());
     }
 
-    public function testUpdated()
+    public function testUpdated(): void
     {
         $controller = $this->makeController();
 
@@ -281,7 +281,7 @@ public function testUpdated()
         $this->assertSame($this->formatter->format(['id' => 3]), $this->response->getBody());
     }
 
-    public function testUnauthorized()
+    public function testUnauthorized(): void
     {
         $controller = $this->makeController();
 
@@ -299,7 +299,7 @@ public function testUnauthorized()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testForbidden()
+    public function testForbidden(): void
     {
         $controller = $this->makeController();
 
@@ -317,7 +317,7 @@ public function testForbidden()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testNoContent()
+    public function testNoContent(): void
     {
         $controller = $this->makeController();
 
@@ -328,7 +328,7 @@ public function testNoContent()
         $this->assertSame(204, $this->response->getStatusCode());
     }
 
-    public function testNotFound()
+    public function testNotFound(): void
     {
         $controller = $this->makeController();
 
@@ -346,7 +346,7 @@ public function testNotFound()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testValidationError()
+    public function testValidationError(): void
     {
         $controller = $this->makeController();
 
@@ -364,7 +364,7 @@ public function testValidationError()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testValidationErrors()
+    public function testValidationErrors(): void
     {
         $controller = $this->makeController();
 
@@ -383,7 +383,7 @@ public function testValidationErrors()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testResourceExists()
+    public function testResourceExists(): void
     {
         $controller = $this->makeController();
 
@@ -401,7 +401,7 @@ public function testResourceExists()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testResourceGone()
+    public function testResourceGone(): void
     {
         $controller = $this->makeController();
 
@@ -419,7 +419,7 @@ public function testResourceGone()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testTooManyRequests()
+    public function testTooManyRequests(): void
     {
         $controller = $this->makeController();
 
@@ -437,7 +437,7 @@ public function testTooManyRequests()
         $this->assertSame($this->formatter->format($expected), $this->response->getBody());
     }
 
-    public function testServerError()
+    public function testServerError(): void
     {
         $controller = $this->makeController();
 
@@ -454,7 +454,7 @@ public function testServerError()
         ]), $this->response->getBody());
     }
 
-    public function testValidContentTypes()
+    public function testValidContentTypes(): void
     {
         $chars     = '; charset=UTF-8';
         $goodMimes = [
@@ -469,7 +469,7 @@ public function testValidContentTypes()
         }
     }
 
-    private function tryValidContentType($mimeType, $contentType)
+    private function tryValidContentType($mimeType, $contentType): void
     {
         $original                = $_SERVER;
         $_SERVER['CONTENT_TYPE'] = $mimeType;
@@ -482,7 +482,7 @@ private function tryValidContentType($mimeType, $contentType)
         $_SERVER = $original;
     }
 
-    public function testValidResponses()
+    public function testValidResponses(): void
     {
         $chars     = '; charset=UTF-8';
         $goodMimes = [
@@ -497,7 +497,7 @@ public function testValidResponses()
         }
     }
 
-    public function testXMLFormatter()
+    public function testXMLFormatter(): void
     {
         $this->formatter = new XMLFormatter();
         $controller      = $this->makeController();
@@ -514,7 +514,7 @@ public function testXMLFormatter()
         $this->assertSame($expected, $this->response->getBody());
     }
 
-    public function testFormatByRequestNegotiateIfFormatIsNotJsonOrXML()
+    public function testFormatByRequestNegotiateIfFormatIsNotJsonOrXML(): void
     {
         $config = new App();
 
@@ -559,7 +559,7 @@ public function __construct(&$request, &$response)
         $this->assertStringStartsWith(config('Format')->supportedResponseFormats[0], $response->getHeaderLine('Content-Type'));
     }
 
-    public function testResponseFormat()
+    public function testResponseFormat(): void
     {
         $data       = ['foo' => 'something'];
         $controller = $this->makeController();
@@ -576,7 +576,7 @@ public function testResponseFormat()
         $this->assertStringStartsWith('application/xml', $this->response->getHeaderLine('Content-Type'));
     }
 
-    public function testXMLResponseFormat()
+    public function testXMLResponseFormat(): void
     {
         $data       = ['foo' => 'bar'];
         $controller = $this->makeController();
diff --git a/tests/system/Autoloader/AutoloaderTest.php b/tests/system/Autoloader/AutoloaderTest.php
index bfe7a0fac8da..a116bc9515d6 100644
--- a/tests/system/Autoloader/AutoloaderTest.php
+++ b/tests/system/Autoloader/AutoloaderTest.php
@@ -59,12 +59,12 @@ protected function tearDown(): void
         parent::tearDown();
     }
 
-    public function testLoadStoredClass()
+    public function testLoadStoredClass(): void
     {
         $this->assertInstanceOf('UnnamespacedClass', new UnnamespacedClass());
     }
 
-    public function testInitializeWithInvalidArguments()
+    public function testInitializeWithInvalidArguments(): void
     {
         $this->expectException('InvalidArgumentException');
         $this->expectExceptionMessage("Config array must contain either the 'psr4' key or the 'classmap' key.");
@@ -78,7 +78,7 @@ public function testInitializeWithInvalidArguments()
         (new Autoloader())->initialize($config, $modules);
     }
 
-    public function testInitializeTwice()
+    public function testInitializeTwice(): void
     {
         $loader = new Autoloader();
         $loader->initialize(new Autoload(), new Modules());
@@ -94,7 +94,7 @@ public function testInitializeTwice()
         $this->assertSame('ROOTPATH/app', clean_path($ns['App'][0]));
     }
 
-    public function testServiceAutoLoaderFromShareInstances()
+    public function testServiceAutoLoaderFromShareInstances(): void
     {
         $autoloader = Services::autoloader();
         // look for Home controller, as that should be in base repo
@@ -103,7 +103,7 @@ public function testServiceAutoLoaderFromShareInstances()
         $this->assertSame($expected, realpath($actual) ?: $actual);
     }
 
-    public function testServiceAutoLoader()
+    public function testServiceAutoLoader(): void
     {
         $autoloader = Services::autoloader(false);
         $autoloader->initialize(new Autoload(), new Modules());
@@ -117,7 +117,7 @@ public function testServiceAutoLoader()
         $autoloader->unregister();
     }
 
-    public function testExistingFile()
+    public function testExistingFile(): void
     {
         $actual   = $this->loader->loadClass(Home::class);
         $expected = APPPATH . 'Controllers' . DIRECTORY_SEPARATOR . 'Home.php';
@@ -128,26 +128,26 @@ public function testExistingFile()
         $this->assertSame($expected, $actual);
     }
 
-    public function testMatchesWithPrecedingSlash()
+    public function testMatchesWithPrecedingSlash(): void
     {
         $actual   = $this->loader->loadClass(Home::class);
         $expected = APPPATH . 'Controllers' . DIRECTORY_SEPARATOR . 'Home.php';
         $this->assertSame($expected, $actual);
     }
 
-    public function testMatchesWithFileExtension()
+    public function testMatchesWithFileExtension(): void
     {
         $actual   = $this->loader->loadClass('\App\Controllers\Home.php');
         $expected = APPPATH . 'Controllers' . DIRECTORY_SEPARATOR . 'Home.php';
         $this->assertSame($expected, $actual);
     }
 
-    public function testMissingFile()
+    public function testMissingFile(): void
     {
         $this->assertFalse($this->loader->loadClass('\App\Missing\Classname'));
     }
 
-    public function testAddNamespaceWorks()
+    public function testAddNamespaceWorks(): void
     {
         $this->assertFalse($this->loader->loadClass('My\App\Class'));
 
@@ -159,7 +159,7 @@ public function testAddNamespaceWorks()
         $this->assertSame($expected, $actual);
     }
 
-    public function testAddNamespaceMultiplePathsWorks()
+    public function testAddNamespaceMultiplePathsWorks(): void
     {
         $this->loader->addNamespace([
             'My\App' => [
@@ -177,7 +177,7 @@ public function testAddNamespaceMultiplePathsWorks()
         $this->assertSame($expected, $actual);
     }
 
-    public function testAddNamespaceStringToArray()
+    public function testAddNamespaceStringToArray(): void
     {
         $this->loader->addNamespace('App\Controllers', __DIR__);
 
@@ -187,7 +187,7 @@ public function testAddNamespaceStringToArray()
         );
     }
 
-    public function testGetNamespaceGivesArray()
+    public function testGetNamespaceGivesArray(): void
     {
         $this->assertSame([
             'App'         => [APPPATH],
@@ -198,7 +198,7 @@ public function testGetNamespaceGivesArray()
         $this->assertSame([], $this->loader->getNamespace('Foo'));
     }
 
-    public function testRemoveNamespace()
+    public function testRemoveNamespace(): void
     {
         $this->loader->addNamespace('My\App', __DIR__);
         $this->assertSame(__FILE__, $this->loader->loadClass('My\App\AutoloaderTest'));
@@ -207,12 +207,12 @@ public function testRemoveNamespace()
         $this->assertFalse((bool) $this->loader->loadClass('My\App\AutoloaderTest'));
     }
 
-    public function testloadClassNonNamespaced()
+    public function testloadClassNonNamespaced(): void
     {
         $this->assertFalse($this->loader->loadClass('Modules'));
     }
 
-    public function testSanitizationContailsSpecialChars()
+    public function testSanitizationContailsSpecialChars(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage(
@@ -224,7 +224,7 @@ public function testSanitizationContailsSpecialChars()
         $this->loader->sanitizeFilename($test);
     }
 
-    public function testSanitizationFilenameEdges()
+    public function testSanitizationFilenameEdges(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage(
@@ -236,7 +236,7 @@ public function testSanitizationFilenameEdges()
         $this->loader->sanitizeFilename($test);
     }
 
-    public function testSanitizationRegexError()
+    public function testSanitizationRegexError(): void
     {
         $this->expectException(RuntimeException::class);
 
@@ -245,21 +245,21 @@ public function testSanitizationRegexError()
         $this->loader->sanitizeFilename($test);
     }
 
-    public function testSanitizationAllowUnicodeChars()
+    public function testSanitizationAllowUnicodeChars(): void
     {
         $test = 'Ä/path/to/some/file.php';
 
         $this->assertSame($test, $this->loader->sanitizeFilename($test));
     }
 
-    public function testSanitizationAllowsWindowsFilepaths()
+    public function testSanitizationAllowsWindowsFilepaths(): void
     {
         $test = 'C:\path\to\some/file.php';
 
         $this->assertSame($test, $this->loader->sanitizeFilename($test));
     }
 
-    public function testFindsComposerRoutes()
+    public function testFindsComposerRoutes(): void
     {
         $config                      = new Autoload();
         $modules                     = new Modules();
@@ -272,7 +272,7 @@ public function testFindsComposerRoutes()
         $this->assertArrayHasKey('Laminas\\Escaper', $namespaces);
     }
 
-    public function testComposerNamespaceDoesNotOverwriteConfigAutoloadPsr4()
+    public function testComposerNamespaceDoesNotOverwriteConfigAutoloadPsr4(): void
     {
         $config       = new Autoload();
         $config->psr4 = [
@@ -289,7 +289,7 @@ public function testComposerNamespaceDoesNotOverwriteConfigAutoloadPsr4()
         $this->assertStringContainsString(VENDORPATH, $namespaces['Psr\Log'][1]);
     }
 
-    public function testComposerPackagesOnly()
+    public function testComposerPackagesOnly(): void
     {
         $config                      = new Autoload();
         $config->psr4                = [];
@@ -306,7 +306,7 @@ public function testComposerPackagesOnly()
         $this->assertStringContainsString(VENDORPATH, $namespaces['Laminas\Escaper'][0]);
     }
 
-    public function testComposerPackagesExclude()
+    public function testComposerPackagesExclude(): void
     {
         $config                      = new Autoload();
         $config->psr4                = [];
@@ -328,7 +328,7 @@ public function testComposerPackagesExclude()
         $this->assertArrayNotHasKey('Laminas\\Escaper', $namespaces);
     }
 
-    public function testComposerPackagesOnlyAndExclude()
+    public function testComposerPackagesOnlyAndExclude(): void
     {
         $this->expectException(ConfigException::class);
         $this->expectExceptionMessage('Cannot use "only" and "exclude" at the same time in "Config\Modules::$composerPackages".');
@@ -346,7 +346,7 @@ public function testComposerPackagesOnlyAndExclude()
         $loader->initialize($config, $modules);
     }
 
-    public function testFindsComposerRoutesWithComposerPathNotFound()
+    public function testFindsComposerRoutesWithComposerPathNotFound(): void
     {
         $composerPath = COMPOSER_PATH;
 
diff --git a/tests/system/Autoloader/FileLocatorTest.php b/tests/system/Autoloader/FileLocatorTest.php
index fc5f56a66d3b..1cf32cfa5ad1 100644
--- a/tests/system/Autoloader/FileLocatorTest.php
+++ b/tests/system/Autoloader/FileLocatorTest.php
@@ -51,7 +51,7 @@ protected function setUp(): void
         $this->locator = new FileLocator($autoloader);
     }
 
-    public function testLocateFileNotNamespacedFindsInAppDirectory()
+    public function testLocateFileNotNamespacedFindsInAppDirectory(): void
     {
         $file = 'Controllers/Home'; // not namespaced
 
@@ -60,14 +60,14 @@ public function testLocateFileNotNamespacedFindsInAppDirectory()
         $this->assertSame($expected, $this->locator->locateFile($file));
     }
 
-    public function testLocateFileNotNamespacedNotFound()
+    public function testLocateFileNotNamespacedNotFound(): void
     {
         $file = 'Unknown'; // not namespaced
 
         $this->assertFalse($this->locator->locateFile($file));
     }
 
-    public function testLocateFileNotNamespacedFindsWithFolderInAppDirectory()
+    public function testLocateFileNotNamespacedFindsWithFolderInAppDirectory(): void
     {
         $file = 'welcome_message'; // not namespaced
 
@@ -76,7 +76,7 @@ public function testLocateFileNotNamespacedFindsWithFolderInAppDirectory()
         $this->assertSame($expected, $this->locator->locateFile($file, 'Views'));
     }
 
-    public function testLocateFileNotNamespacedFindesWithoutFolderInAppDirectory()
+    public function testLocateFileNotNamespacedFindesWithoutFolderInAppDirectory(): void
     {
         $file = 'Common'; // not namespaced
 
@@ -85,7 +85,7 @@ public function testLocateFileNotNamespacedFindesWithoutFolderInAppDirectory()
         $this->assertSame($expected, $this->locator->locateFile($file));
     }
 
-    public function testLocateFileNotNamespacedWorksInNestedAppDirectory()
+    public function testLocateFileNotNamespacedWorksInNestedAppDirectory(): void
     {
         $file = 'Controllers/Home'; // not namespaced
 
@@ -95,7 +95,7 @@ public function testLocateFileNotNamespacedWorksInNestedAppDirectory()
         $this->assertSame($expected, $this->locator->locateFile($file, 'Controllers'));
     }
 
-    public function testLocateFileWithFolderNameInFile()
+    public function testLocateFileWithFolderNameInFile(): void
     {
         $file = '\App\Views/errors/html/error_404.php';
 
@@ -105,7 +105,7 @@ public function testLocateFileWithFolderNameInFile()
         $this->assertSame($expected, $this->locator->locateFile($file, 'Views'));
     }
 
-    public function testLocateFileNotNamespacedWithFolderNameInFile()
+    public function testLocateFileNotNamespacedWithFolderNameInFile(): void
     {
         $file = 'Views/welcome_message.php'; // not namespaced
 
@@ -115,7 +115,7 @@ public function testLocateFileNotNamespacedWithFolderNameInFile()
         $this->assertSame($expected, $this->locator->locateFile($file, 'Views'));
     }
 
-    public function testLocateFileCanFindNamespacedView()
+    public function testLocateFileCanFindNamespacedView(): void
     {
         $file = '\Errors\error_404';
 
@@ -125,7 +125,7 @@ public function testLocateFileCanFindNamespacedView()
         $this->assertSame($expected, $this->locator->locateFile($file, 'html'));
     }
 
-    public function testLocateFileCanFindNestedNamespacedView()
+    public function testLocateFileCanFindNestedNamespacedView(): void
     {
         $file = '\Errors\html/error_404';
 
@@ -134,7 +134,7 @@ public function testLocateFileCanFindNestedNamespacedView()
         $this->assertSame($expected, $this->locator->locateFile($file, 'html'));
     }
 
-    public function testLocateFileCanFindNamespacedViewWhenVendorHasTwoNamespaces()
+    public function testLocateFileCanFindNamespacedViewWhenVendorHasTwoNamespaces(): void
     {
         $file = '\CodeIgniter\Devkit\View\Views/simple';
 
@@ -143,21 +143,21 @@ public function testLocateFileCanFindNamespacedViewWhenVendorHasTwoNamespaces()
         $this->assertSame($expected, $this->locator->locateFile($file, 'Views'));
     }
 
-    public function testLocateFileNotFoundExistingNamespace()
+    public function testLocateFileNotFoundExistingNamespace(): void
     {
         $file = '\App\Views/unexistence-file.php';
 
         $this->assertFalse($this->locator->locateFile($file, 'Views'));
     }
 
-    public function testLocateFileNotFoundWithBadNamespace()
+    public function testLocateFileNotFoundWithBadNamespace(): void
     {
         $file = '\Blogger\admin/posts.php';
 
         $this->assertFalse($this->locator->locateFile($file, 'Views'));
     }
 
-    public function testLocateFileWithProperNamespace()
+    public function testLocateFileWithProperNamespace(): void
     {
         $file = 'Acme\SampleProject\View\Views\simple';
 
@@ -166,7 +166,7 @@ public function testLocateFileWithProperNamespace()
         $this->assertSame($expected, $this->locator->locateFile($file, 'Views'));
     }
 
-    public function testSearchSimple()
+    public function testSearchSimple(): void
     {
         $expected = APPPATH . 'Config/App.php';
 
@@ -175,7 +175,7 @@ public function testSearchSimple()
         $this->assertSame($expected, $foundFiles[0]);
     }
 
-    public function testSearchWithFileExtension()
+    public function testSearchWithFileExtension(): void
     {
         $expected = APPPATH . 'Config/App.php';
 
@@ -184,7 +184,7 @@ public function testSearchWithFileExtension()
         $this->assertSame($expected, $foundFiles[0]);
     }
 
-    public function testSearchWithMultipleFilesFound()
+    public function testSearchWithMultipleFilesFound(): void
     {
         $foundFiles = $this->locator->search('index', 'html');
 
@@ -195,14 +195,14 @@ public function testSearchWithMultipleFilesFound()
         $this->assertContains($expected, $foundFiles);
     }
 
-    public function testSearchForFileNotExist()
+    public function testSearchForFileNotExist(): void
     {
         $foundFiles = $this->locator->search('Views/Fake.html');
 
         $this->assertArrayNotHasKey(0, $foundFiles);
     }
 
-    public function testSearchPrioritizeSystemOverApp()
+    public function testSearchPrioritizeSystemOverApp(): void
     {
         $foundFiles = $this->locator->search('Language/en/Validation.php', 'php', false);
 
@@ -215,12 +215,12 @@ public function testSearchPrioritizeSystemOverApp()
         );
     }
 
-    public function testListNamespaceFilesEmptyPrefixAndPath()
+    public function testListNamespaceFilesEmptyPrefixAndPath(): void
     {
         $this->assertEmpty($this->locator->listNamespaceFiles('', ''));
     }
 
-    public function testListFilesSimple()
+    public function testListFilesSimple(): void
     {
         $files = $this->locator->listFiles('Config/');
 
@@ -229,7 +229,7 @@ public function testListFilesSimple()
         $this->assertTrue(in_array($expectedWin, $files, true) || in_array($expectedLin, $files, true));
     }
 
-    public function testListFilesDoesNotContainDirectories()
+    public function testListFilesDoesNotContainDirectories(): void
     {
         $files = $this->locator->listFiles('Config/');
 
@@ -241,14 +241,14 @@ public function testListFilesDoesNotContainDirectories()
         $this->assertNotContains($directory, $files);
     }
 
-    public function testListFilesWithFileAsInput()
+    public function testListFilesWithFileAsInput(): void
     {
         $files = $this->locator->listFiles('Config/App.php');
 
         $this->assertEmpty($files);
     }
 
-    public function testListFilesFromMultipleDir()
+    public function testListFilesFromMultipleDir(): void
     {
         $files = $this->locator->listFiles('Filters/');
 
@@ -261,21 +261,21 @@ public function testListFilesFromMultipleDir()
         $this->assertTrue(in_array($expectedWin, $files, true) || in_array($expectedLin, $files, true));
     }
 
-    public function testListFilesWithPathNotExist()
+    public function testListFilesWithPathNotExist(): void
     {
         $files = $this->locator->listFiles('Fake/');
 
         $this->assertEmpty($files);
     }
 
-    public function testListFilesWithoutPath()
+    public function testListFilesWithoutPath(): void
     {
         $files = $this->locator->listFiles('');
 
         $this->assertEmpty($files);
     }
 
-    public function testFindQNameFromPathSimple()
+    public function testFindQNameFromPathSimple(): void
     {
         $ClassName = $this->locator->findQualifiedNameFromPath(SYSTEMPATH . 'HTTP/Header.php');
         $expected  = '\\' . Header::class;
@@ -283,21 +283,21 @@ public function testFindQNameFromPathSimple()
         $this->assertSame($expected, $ClassName);
     }
 
-    public function testFindQNameFromPathWithFileNotExist()
+    public function testFindQNameFromPathWithFileNotExist(): void
     {
         $ClassName = $this->locator->findQualifiedNameFromPath('modules/blog/Views/index.php');
 
         $this->assertFalse($ClassName);
     }
 
-    public function testFindQNameFromPathWithoutCorrespondingNamespace()
+    public function testFindQNameFromPathWithoutCorrespondingNamespace(): void
     {
         $ClassName = $this->locator->findQualifiedNameFromPath('/etc/hosts');
 
         $this->assertFalse($ClassName);
     }
 
-    public function testGetClassNameFromClassFile()
+    public function testGetClassNameFromClassFile(): void
     {
         $this->assertSame(
             self::class,
@@ -305,7 +305,7 @@ public function testGetClassNameFromClassFile()
         );
     }
 
-    public function testGetClassNameFromNonClassFile()
+    public function testGetClassNameFromNonClassFile(): void
     {
         $this->assertSame(
             '',
diff --git a/tests/system/CLI/CLITest.php b/tests/system/CLI/CLITest.php
index 3068328aa9a8..e02db8d97515 100644
--- a/tests/system/CLI/CLITest.php
+++ b/tests/system/CLI/CLITest.php
@@ -26,21 +26,21 @@ final class CLITest extends CIUnitTestCase
 {
     use StreamFilterTrait;
 
-    public function testNew()
+    public function testNew(): void
     {
         $actual = new CLI();
 
         $this->assertInstanceOf(CLI::class, $actual);
     }
 
-    public function testBeep()
+    public function testBeep(): void
     {
         $this->expectOutputString("\x07");
 
         CLI::beep();
     }
 
-    public function testBeep4()
+    public function testBeep4(): void
     {
         $this->expectOutputString("\x07\x07\x07\x07");
 
@@ -53,7 +53,7 @@ public function testBeep4()
      *
      * @timeLimit 2.5
      */
-    public function testWait()
+    public function testWait(): void
     {
         $time = time();
         CLI::wait(1, true);
@@ -64,7 +64,7 @@ public function testWait()
         $this->assertCloseEnough(1, time() - $time);
     }
 
-    public function testWaitZero()
+    public function testWaitZero(): void
     {
         PhpStreamWrapper::register();
         PhpStreamWrapper::setContent(' ');
@@ -78,7 +78,7 @@ public function testWaitZero()
         PhpStreamWrapper::restore();
     }
 
-    public function testPrompt()
+    public function testPrompt(): void
     {
         PhpStreamWrapper::register();
 
@@ -92,7 +92,7 @@ public function testPrompt()
         PhpStreamWrapper::restore();
     }
 
-    public function testPromptByMultipleKeys()
+    public function testPromptByMultipleKeys(): void
     {
         PhpStreamWrapper::register();
 
@@ -112,14 +112,14 @@ public function testPromptByMultipleKeys()
         PhpStreamWrapper::restore();
     }
 
-    public function testNewLine()
+    public function testNewLine(): void
     {
         $this->expectOutputString('');
 
         CLI::newLine();
     }
 
-    public function testColorExceptionForeground()
+    public function testColorExceptionForeground(): void
     {
         $this->expectException(RuntimeException::class);
         $this->expectExceptionMessage('Invalid "foreground" color: "Foreground"');
@@ -127,7 +127,7 @@ public function testColorExceptionForeground()
         CLI::color('test', 'Foreground');
     }
 
-    public function testColorExceptionBackground()
+    public function testColorExceptionBackground(): void
     {
         $this->expectException(RuntimeException::class);
         $this->expectExceptionMessage('Invalid "background" color: "Background"');
@@ -135,7 +135,7 @@ public function testColorExceptionBackground()
         CLI::color('test', 'white', 'Background');
     }
 
-    public function testColorSupportOnNoColor()
+    public function testColorSupportOnNoColor(): void
     {
         $nocolor = getenv('NO_COLOR');
         putenv('NO_COLOR=1');
@@ -146,7 +146,7 @@ public function testColorSupportOnNoColor()
         putenv($nocolor ? "NO_COLOR={$nocolor}" : 'NO_COLOR');
     }
 
-    public function testColorSupportOnHyperTerminals()
+    public function testColorSupportOnHyperTerminals(): void
     {
         $termProgram = getenv('TERM_PROGRAM');
         putenv('TERM_PROGRAM=Hyper');
@@ -157,13 +157,13 @@ public function testColorSupportOnHyperTerminals()
         putenv($termProgram ? "TERM_PROGRAM={$termProgram}" : 'TERM_PROGRAM');
     }
 
-    public function testStreamSupports()
+    public function testStreamSupports(): void
     {
         $this->assertTrue(CLI::streamSupports('stream_isatty', STDOUT));
         $this->assertIsBool(CLI::streamSupports('sapi_windows_vt100_support', STDOUT));
     }
 
-    public function testColor()
+    public function testColor(): void
     {
         // After the tests on NO_COLOR and TERM_PROGRAM above,
         // the $isColored variable is rigged. So we reset this.
@@ -175,7 +175,7 @@ public function testColor()
         );
     }
 
-    public function testColorEmtpyString()
+    public function testColorEmtpyString(): void
     {
         $this->assertSame(
             '',
@@ -183,7 +183,7 @@ public function testColorEmtpyString()
         );
     }
 
-    public function testPrint()
+    public function testPrint(): void
     {
         CLI::print('test');
 
@@ -191,7 +191,7 @@ public function testPrint()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testPrintForeground()
+    public function testPrintForeground(): void
     {
         CLI::print('test', 'red');
 
@@ -199,7 +199,7 @@ public function testPrintForeground()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testPrintBackground()
+    public function testPrintBackground(): void
     {
         CLI::print('test', 'red', 'green');
 
@@ -207,7 +207,7 @@ public function testPrintBackground()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         CLI::write('test');
 
@@ -215,7 +215,7 @@ public function testWrite()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testWriteForeground()
+    public function testWriteForeground(): void
     {
         CLI::write('test', 'red');
 
@@ -223,7 +223,7 @@ public function testWriteForeground()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testWriteForegroundWithColorBefore()
+    public function testWriteForegroundWithColorBefore(): void
     {
         CLI::write(CLI::color('green', 'green') . ' red', 'red');
 
@@ -231,7 +231,7 @@ public function testWriteForegroundWithColorBefore()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testWriteForegroundWithColorAfter()
+    public function testWriteForegroundWithColorAfter(): void
     {
         CLI::write('red ' . CLI::color('green', 'green'), 'red');
 
@@ -242,7 +242,7 @@ public function testWriteForegroundWithColorAfter()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5892
      */
-    public function testWriteForegroundWithColorTwice()
+    public function testWriteForegroundWithColorTwice(): void
     {
         CLI::write(
             CLI::color('green', 'green') . ' red ' . CLI::color('green', 'green'),
@@ -253,7 +253,7 @@ public function testWriteForegroundWithColorTwice()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testWriteBackground()
+    public function testWriteBackground(): void
     {
         CLI::write('test', 'red', 'green');
 
@@ -261,7 +261,7 @@ public function testWriteBackground()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testError()
+    public function testError(): void
     {
         CLI::error('test');
 
@@ -270,7 +270,7 @@ public function testError()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testErrorForeground()
+    public function testErrorForeground(): void
     {
         CLI::error('test', 'purple');
 
@@ -278,7 +278,7 @@ public function testErrorForeground()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testErrorBackground()
+    public function testErrorBackground(): void
     {
         CLI::error('test', 'purple', 'green');
 
@@ -286,7 +286,7 @@ public function testErrorBackground()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testShowProgress()
+    public function testShowProgress(): void
     {
         CLI::write('first.');
         CLI::showProgress(1, 20);
@@ -312,7 +312,7 @@ public function testShowProgress()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testShowProgressWithoutBar()
+    public function testShowProgressWithoutBar(): void
     {
         CLI::write('first.');
         CLI::showProgress(false, 20);
@@ -323,7 +323,7 @@ public function testShowProgressWithoutBar()
         $this->assertSame($expected, $this->getStreamFilterBuffer());
     }
 
-    public function testWrap()
+    public function testWrap(): void
     {
         $this->assertSame('', CLI::wrap(''));
         $this->assertSame(
@@ -340,7 +340,7 @@ public function testWrap()
         );
     }
 
-    public function testParseCommand()
+    public function testParseCommand(): void
     {
         $_SERVER['argv'] = [
             'ignored',
@@ -359,7 +359,7 @@ public function testParseCommand()
         $this->assertSame(['b', 'c'], CLI::getSegments());
     }
 
-    public function testParseCommandMixed()
+    public function testParseCommandMixed(): void
     {
         $_SERVER['argv'] = [
             'ignored',
@@ -388,7 +388,7 @@ public function testParseCommandMixed()
         $this->assertSame('--parm pvalue --fix --opt-in sure', CLI::getOptionString(true, true));
     }
 
-    public function testParseCommandOption()
+    public function testParseCommandOption(): void
     {
         $_SERVER['argv'] = [
             'ignored',
@@ -410,7 +410,7 @@ public function testParseCommandOption()
         $this->assertSame(['b', 'c', 'd'], CLI::getSegments());
     }
 
-    public function testParseCommandMultipleOptions()
+    public function testParseCommandMultipleOptions(): void
     {
         $_SERVER['argv'] = [
             'ignored',
@@ -434,7 +434,7 @@ public function testParseCommandMultipleOptions()
         $this->assertSame(['b', 'c', 'd'], CLI::getSegments());
     }
 
-    public function testWindow()
+    public function testWindow(): void
     {
         $height = new ReflectionProperty(CLI::class, 'height');
         $height->setAccessible(true);
@@ -456,7 +456,7 @@ public function testWindow()
      * @param array $thead
      * @param array $expected
      */
-    public function testTable($tbody, $thead, $expected)
+    public function testTable($tbody, $thead, $expected): void
     {
         CLI::table($tbody, $thead);
 
@@ -548,7 +548,7 @@ public function tableProvider(): iterable
         ];
     }
 
-    public function testStrlen()
+    public function testStrlen(): void
     {
         $this->assertSame(18, mb_strlen(CLI::color('success', 'green')));
         $this->assertSame(7, CLI::strlen(CLI::color('success', 'green')));
diff --git a/tests/system/CLI/ConsoleTest.php b/tests/system/CLI/ConsoleTest.php
index ec1198287906..78bc5415b8ed 100644
--- a/tests/system/CLI/ConsoleTest.php
+++ b/tests/system/CLI/ConsoleTest.php
@@ -45,7 +45,7 @@ protected function setUp(): void
         $this->app->initialize();
     }
 
-    public function testHeader()
+    public function testHeader(): void
     {
         $console = new Console();
         $console->showHeader();
@@ -58,14 +58,14 @@ public function testHeader()
         );
     }
 
-    public function testNoHeader()
+    public function testNoHeader(): void
     {
         $console = new Console();
         $console->showHeader(true);
         $this->assertSame('', $this->getStreamFilterBuffer());
     }
 
-    public function testRun()
+    public function testRun(): void
     {
         $this->initCLI();
 
@@ -77,7 +77,7 @@ public function testRun()
         $this->assertStringContainsString('Displays basic usage information.', $this->getStreamFilterBuffer());
     }
 
-    public function testBadCommand()
+    public function testBadCommand(): void
     {
         $this->initCLI('bogus');
 
@@ -88,7 +88,7 @@ public function testBadCommand()
         $this->assertStringContainsString('Command "bogus" not found', $this->getStreamFilterBuffer());
     }
 
-    public function testHelpCommandDetails()
+    public function testHelpCommandDetails(): void
     {
         $this->initCLI('help', 'session:migration');
 
@@ -101,7 +101,7 @@ public function testHelpCommandDetails()
         $this->assertStringContainsString('Options:', $this->getStreamFilterBuffer());
     }
 
-    public function testHelpCommandUsingHelpOption()
+    public function testHelpCommandUsingHelpOption(): void
     {
         $this->initCLI('env', '--help');
 
@@ -114,7 +114,7 @@ public function testHelpCommandUsingHelpOption()
         );
     }
 
-    public function testHelpOptionIsOnlyPassed()
+    public function testHelpOptionIsOnlyPassed(): void
     {
         $this->initCLI('--help');
 
@@ -125,7 +125,7 @@ public function testHelpOptionIsOnlyPassed()
         $this->assertStringContainsString('Lists the available commands.', $this->getStreamFilterBuffer());
     }
 
-    public function testHelpArgumentAndHelpOptionCombined()
+    public function testHelpArgumentAndHelpOptionCombined(): void
     {
         $this->initCLI('help', '--help');
 
diff --git a/tests/system/Cache/CacheFactoryTest.php b/tests/system/Cache/CacheFactoryTest.php
index 3b1288c157bd..1ca778b28faa 100644
--- a/tests/system/Cache/CacheFactoryTest.php
+++ b/tests/system/Cache/CacheFactoryTest.php
@@ -46,12 +46,12 @@ protected function tearDown(): void
         }
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $this->assertInstanceOf(CacheFactory::class, $this->cacheFactory);
     }
 
-    public function testGetHandlerExceptionCacheInvalidHandlers()
+    public function testGetHandlerExceptionCacheInvalidHandlers(): void
     {
         $this->expectException(CacheException::class);
         $this->expectExceptionMessage('Cache config must have an array of $validHandlers.');
@@ -61,7 +61,7 @@ public function testGetHandlerExceptionCacheInvalidHandlers()
         $this->cacheFactory->getHandler($this->config);
     }
 
-    public function testGetHandlerExceptionCacheHandlerNotFound()
+    public function testGetHandlerExceptionCacheHandlerNotFound(): void
     {
         $this->expectException(CacheException::class);
         $this->expectExceptionMessage('Cache config has an invalid handler or backup handler specified.');
@@ -71,7 +71,7 @@ public function testGetHandlerExceptionCacheHandlerNotFound()
         $this->cacheFactory->getHandler($this->config);
     }
 
-    public function testGetDummyHandler()
+    public function testGetDummyHandler(): void
     {
         if (! is_dir($this->config->storePath)) {
             mkdir($this->config->storePath, 0555, true);
@@ -86,7 +86,7 @@ public function testGetDummyHandler()
         $this->config->storePath .= self::$directory;
     }
 
-    public function testHandlesBadHandler()
+    public function testHandlesBadHandler(): void
     {
         if (! is_dir($this->config->storePath)) {
             mkdir($this->config->storePath, 0555, true);
diff --git a/tests/system/Cache/CacheMockTest.php b/tests/system/Cache/CacheMockTest.php
index 492bef9264b8..72a901aa36aa 100644
--- a/tests/system/Cache/CacheMockTest.php
+++ b/tests/system/Cache/CacheMockTest.php
@@ -22,7 +22,7 @@
  */
 final class CacheMockTest extends CIUnitTestCase
 {
-    public function testMockReturnsMockCacheClass()
+    public function testMockReturnsMockCacheClass(): void
     {
         $this->assertInstanceOf(BaseHandler::class, service('cache'));
 
@@ -31,7 +31,7 @@ public function testMockReturnsMockCacheClass()
         $this->assertInstanceOf(MockCache::class, service('cache'));
     }
 
-    public function testMockCaching()
+    public function testMockCaching(): void
     {
         $mock = mock(CacheFactory::class);
 
diff --git a/tests/system/Cache/Handlers/AbstractHandlerTest.php b/tests/system/Cache/Handlers/AbstractHandlerTest.php
index e426e02eb3c5..fbb27971628e 100644
--- a/tests/system/Cache/Handlers/AbstractHandlerTest.php
+++ b/tests/system/Cache/Handlers/AbstractHandlerTest.php
@@ -25,12 +25,12 @@ abstract class AbstractHandlerTest extends CIUnitTestCase
     protected static $key3  = 'key3';
     protected static $dummy = 'dymmy';
 
-    public function testGetMetaDataMiss()
+    public function testGetMetaDataMiss(): void
     {
         $this->assertNull($this->handler->getMetaData(self::$dummy));
     }
 
-    public function testGetMetaData()
+    public function testGetMetaData(): void
     {
         $time = Time::now()->getTimestamp();
         $this->handler->save(self::$key1, 'value');
diff --git a/tests/system/Cache/Handlers/BaseHandlerTest.php b/tests/system/Cache/Handlers/BaseHandlerTest.php
index ba1dd0b2491f..2e835760e9e4 100644
--- a/tests/system/Cache/Handlers/BaseHandlerTest.php
+++ b/tests/system/Cache/Handlers/BaseHandlerTest.php
@@ -27,7 +27,7 @@ final class BaseHandlerTest extends CIUnitTestCase
      *
      * @param mixed $input
      */
-    public function testValidateKeyInvalidType($input)
+    public function testValidateKeyInvalidType($input): void
     {
         $this->expectException('InvalidArgumentException');
         $this->expectExceptionMessage('Cache key must be a string');
@@ -46,7 +46,7 @@ public function invalidTypeProvider(): iterable
         ];
     }
 
-    public function testValidateKeyUsesConfig()
+    public function testValidateKeyUsesConfig(): void
     {
         config('Cache')->reservedCharacters = 'b';
 
@@ -56,7 +56,7 @@ public function testValidateKeyUsesConfig()
         BaseHandler::validateKey('banana');
     }
 
-    public function testValidateKeySuccess()
+    public function testValidateKeySuccess(): void
     {
         $string = 'banana';
         $result = BaseHandler::validateKey($string);
@@ -64,7 +64,7 @@ public function testValidateKeySuccess()
         $this->assertSame($string, $result);
     }
 
-    public function testValidateKeySuccessWithPrefix()
+    public function testValidateKeySuccessWithPrefix(): void
     {
         $string = 'banana';
         $result = BaseHandler::validateKey($string, 'prefix');
@@ -72,7 +72,7 @@ public function testValidateKeySuccessWithPrefix()
         $this->assertSame('prefix' . $string, $result);
     }
 
-    public function testValidateExcessiveLength()
+    public function testValidateExcessiveLength(): void
     {
         $string   = 'MoreThanTenCharacters';
         $expected = md5($string);
@@ -82,7 +82,7 @@ public function testValidateExcessiveLength()
         $this->assertSame($expected, $result);
     }
 
-    public function testValidateExcessiveLengthWithPrefix()
+    public function testValidateExcessiveLengthWithPrefix(): void
     {
         $string   = 'MoreThanTenCharacters';
         $expected = 'prefix' . md5($string);
diff --git a/tests/system/Cache/Handlers/DummyHandlerTest.php b/tests/system/Cache/Handlers/DummyHandlerTest.php
index 71ca66a907d0..79dfda094acf 100644
--- a/tests/system/Cache/Handlers/DummyHandlerTest.php
+++ b/tests/system/Cache/Handlers/DummyHandlerTest.php
@@ -28,64 +28,64 @@ protected function setUp(): void
         $this->handler->initialize();
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $this->assertInstanceOf(DummyHandler::class, $this->handler);
     }
 
-    public function testGet()
+    public function testGet(): void
     {
         $this->assertNull($this->handler->get('key'));
     }
 
-    public function testRemember()
+    public function testRemember(): void
     {
         $dummyHandler = $this->handler->remember('key', 2, static fn () => 'value');
 
         $this->assertNull($dummyHandler);
     }
 
-    public function testSave()
+    public function testSave(): void
     {
         $this->assertTrue($this->handler->save('key', 'value'));
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $this->assertTrue($this->handler->delete('key'));
     }
 
-    public function testDeleteMatching()
+    public function testDeleteMatching(): void
     {
         $this->assertSame(0, $this->handler->deleteMatching('key*'));
     }
 
-    public function testIncrement()
+    public function testIncrement(): void
     {
         $this->assertTrue($this->handler->increment('key'));
     }
 
-    public function testDecrement()
+    public function testDecrement(): void
     {
         $this->assertTrue($this->handler->decrement('key'));
     }
 
-    public function testClean()
+    public function testClean(): void
     {
         $this->assertTrue($this->handler->clean());
     }
 
-    public function testGetCacheInfo()
+    public function testGetCacheInfo(): void
     {
         $this->assertNull($this->handler->getCacheInfo());
     }
 
-    public function testGetMetaData()
+    public function testGetMetaData(): void
     {
         $this->assertNull($this->handler->getMetaData('key'));
     }
 
-    public function testIsSupported()
+    public function testIsSupported(): void
     {
         $this->assertTrue($this->handler->isSupported());
     }
diff --git a/tests/system/Cache/Handlers/FileHandlerTest.php b/tests/system/Cache/Handlers/FileHandlerTest.php
index 6f5e6b82f8c5..db8387b8c9cf 100644
--- a/tests/system/Cache/Handlers/FileHandlerTest.php
+++ b/tests/system/Cache/Handlers/FileHandlerTest.php
@@ -73,7 +73,7 @@ protected function tearDown(): void
         }
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $this->assertInstanceOf(FileHandler::class, $this->handler);
     }
@@ -83,7 +83,7 @@ public function testNew()
      *
      * @requires OS Linux|Darwin
      */
-    public function testNewWithNonWritablePath()
+    public function testNewWithNonWritablePath(): void
     {
         $this->expectException(CacheException::class);
 
@@ -91,7 +91,7 @@ public function testNewWithNonWritablePath()
         new FileHandler($this->config);
     }
 
-    public function testSetDefaultPath()
+    public function testSetDefaultPath(): void
     {
         // Initialize path
         $config                    = new Cache();
@@ -109,7 +109,7 @@ public function testSetDefaultPath()
      *
      * @timeLimit 3.5
      */
-    public function testGet()
+    public function testGet(): void
     {
         $this->handler->save(self::$key1, 'value', 2);
 
@@ -126,7 +126,7 @@ public function testGet()
      *
      * @timeLimit 3.5
      */
-    public function testRemember()
+    public function testRemember(): void
     {
         $this->handler->remember(self::$key1, 2, static fn () => 'value');
 
@@ -142,7 +142,7 @@ public function testRemember()
      *
      * @requires OS Linux|Darwin
      */
-    public function testSave()
+    public function testSave(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value'));
 
@@ -150,7 +150,7 @@ public function testSave()
         $this->assertFalse($this->handler->save(self::$key2, 'value'));
     }
 
-    public function testSaveExcessiveKeyLength()
+    public function testSaveExcessiveKeyLength(): void
     {
         $key  = str_repeat('a', 260);
         $file = $this->config->file['storePath'] . DIRECTORY_SEPARATOR . md5($key);
@@ -161,7 +161,7 @@ public function testSaveExcessiveKeyLength()
         unlink($file);
     }
 
-    public function testSavePermanent()
+    public function testSavePermanent(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value', 0));
         $metaData = $this->handler->getMetaData(self::$key1);
@@ -173,7 +173,7 @@ public function testSavePermanent()
         $this->assertTrue($this->handler->delete(self::$key1));
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $this->handler->save(self::$key1, 'value');
 
@@ -181,7 +181,7 @@ public function testDelete()
         $this->assertFalse($this->handler->delete(self::$dummy));
     }
 
-    public function testDeleteMatchingPrefix()
+    public function testDeleteMatchingPrefix(): void
     {
         // Save 101 items to match on
         for ($i = 1; $i <= 101; $i++) {
@@ -202,7 +202,7 @@ public function testDeleteMatchingPrefix()
         $this->handler->clean();
     }
 
-    public function testDeleteMatchingSuffix()
+    public function testDeleteMatchingSuffix(): void
     {
         // Save 101 items to match on
         for ($i = 1; $i <= 101; $i++) {
@@ -223,7 +223,7 @@ public function testDeleteMatchingSuffix()
         $this->handler->clean();
     }
 
-    public function testIncrement()
+    public function testIncrement(): void
     {
         $this->handler->save(self::$key1, 1);
         $this->handler->save(self::$key2, 'value');
@@ -233,7 +233,7 @@ public function testIncrement()
         $this->assertSame(10, $this->handler->increment(self::$key3, 10));
     }
 
-    public function testDecrement()
+    public function testDecrement(): void
     {
         $this->handler->save(self::$key1, 10);
         $this->handler->save(self::$key2, 'value');
@@ -246,7 +246,7 @@ public function testDecrement()
         $this->assertSame(-1, $this->handler->decrement(self::$key3, 1));
     }
 
-    public function testClean()
+    public function testClean(): void
     {
         $this->handler->save(self::$key1, 1);
         $this->handler->save(self::$key2, 'value');
@@ -257,7 +257,7 @@ public function testClean()
         $this->handler->save(self::$key2, 'value');
     }
 
-    public function testGetCacheInfo()
+    public function testGetCacheInfo(): void
     {
         $this->handler->save(self::$key1, 'value');
 
@@ -267,7 +267,7 @@ public function testGetCacheInfo()
         $this->assertArrayHasKey('server_path', $actual[self::$key1]);
     }
 
-    public function testIsSupported()
+    public function testIsSupported(): void
     {
         $this->assertTrue($this->handler->isSupported());
     }
@@ -318,7 +318,7 @@ public function modeProvider(): iterable
         ];
     }
 
-    public function testFileHandler()
+    public function testFileHandler(): void
     {
         $fileHandler = new BaseTestFileHandler();
 
@@ -333,7 +333,7 @@ public function testFileHandler()
         $this->assertArrayHasKey('fileperms', $actual);
     }
 
-    public function testGetMetaDataMiss()
+    public function testGetMetaDataMiss(): void
     {
         $this->assertFalse($this->handler->getMetaData(self::$dummy));
     }
diff --git a/tests/system/Cache/Handlers/MemcachedHandlerTest.php b/tests/system/Cache/Handlers/MemcachedHandlerTest.php
index 24465af9e7de..986507d3e180 100644
--- a/tests/system/Cache/Handlers/MemcachedHandlerTest.php
+++ b/tests/system/Cache/Handlers/MemcachedHandlerTest.php
@@ -56,7 +56,7 @@ protected function tearDown(): void
         }
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $this->assertInstanceOf(MemcachedHandler::class, $this->handler);
     }
@@ -67,7 +67,7 @@ public function testNew()
      *
      * @timeLimit 3.5
      */
-    public function testGet()
+    public function testGet(): void
     {
         $this->handler->save(self::$key1, 'value', 2);
 
@@ -84,7 +84,7 @@ public function testGet()
      *
      * @timeLimit 3.5
      */
-    public function testRemember()
+    public function testRemember(): void
     {
         $this->handler->remember(self::$key1, 2, static fn () => 'value');
 
@@ -95,12 +95,12 @@ public function testRemember()
         $this->assertNull($this->handler->get(self::$key1));
     }
 
-    public function testSave()
+    public function testSave(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value'));
     }
 
-    public function testSavePermanent()
+    public function testSavePermanent(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value', 0));
         $metaData = $this->handler->getMetaData(self::$key1);
@@ -112,7 +112,7 @@ public function testSavePermanent()
         $this->assertTrue($this->handler->delete(self::$key1));
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $this->handler->save(self::$key1, 'value');
 
@@ -120,7 +120,7 @@ public function testDelete()
         $this->assertFalse($this->handler->delete(self::$dummy));
     }
 
-    public function testDeleteMatching()
+    public function testDeleteMatching(): void
     {
         // Not implemented for Memcached, should throw an exception
         $this->expectException(Exception::class);
@@ -128,7 +128,7 @@ public function testDeleteMatching()
         $this->handler->deleteMatching('key*');
     }
 
-    public function testIncrement()
+    public function testIncrement(): void
     {
         $this->handler->save(self::$key1, 1);
 
@@ -147,7 +147,7 @@ public function testIncrement()
         $this->assertSame(10, $memcachedHandler->increment(self::$key3, 10));
     }
 
-    public function testDecrement()
+    public function testDecrement(): void
     {
         $this->handler->save(self::$key1, 10);
 
@@ -166,7 +166,7 @@ public function testDecrement()
         $this->assertSame(1, $memcachedHandler->decrement(self::$key3, 1));
     }
 
-    public function testClean()
+    public function testClean(): void
     {
         $this->handler->save(self::$key1, 1);
         $this->handler->save(self::$key2, 'value');
@@ -174,19 +174,19 @@ public function testClean()
         $this->assertTrue($this->handler->clean());
     }
 
-    public function testGetCacheInfo()
+    public function testGetCacheInfo(): void
     {
         $this->handler->save(self::$key1, 'value');
 
         $this->assertIsArray($this->handler->getCacheInfo());
     }
 
-    public function testIsSupported()
+    public function testIsSupported(): void
     {
         $this->assertTrue($this->handler->isSupported());
     }
 
-    public function testGetMetaDataMiss()
+    public function testGetMetaDataMiss(): void
     {
         $this->assertFalse($this->handler->getMetaData(self::$dummy));
     }
diff --git a/tests/system/Cache/Handlers/PredisHandlerTest.php b/tests/system/Cache/Handlers/PredisHandlerTest.php
index 17a43e36263f..e1677ba6a1b0 100644
--- a/tests/system/Cache/Handlers/PredisHandlerTest.php
+++ b/tests/system/Cache/Handlers/PredisHandlerTest.php
@@ -51,12 +51,12 @@ protected function tearDown(): void
         }
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $this->assertInstanceOf(PredisHandler::class, $this->handler);
     }
 
-    public function testDestruct()
+    public function testDestruct(): void
     {
         $this->handler = new PredisHandler($this->config);
         $this->handler->initialize();
@@ -70,7 +70,7 @@ public function testDestruct()
      *
      * @timeLimit 3.5
      */
-    public function testGet()
+    public function testGet(): void
     {
         $this->handler->save(self::$key1, 'value', 2);
 
@@ -87,7 +87,7 @@ public function testGet()
      *
      * @timeLimit 3.5
      */
-    public function testRemember()
+    public function testRemember(): void
     {
         $this->handler->remember(self::$key1, 2, static fn () => 'value');
 
@@ -98,12 +98,12 @@ public function testRemember()
         $this->assertNull($this->handler->get(self::$key1));
     }
 
-    public function testSave()
+    public function testSave(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value'));
     }
 
-    public function testSavePermanent()
+    public function testSavePermanent(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value', 0));
         $metaData = $this->handler->getMetaData(self::$key1);
@@ -115,7 +115,7 @@ public function testSavePermanent()
         $this->assertTrue($this->handler->delete(self::$key1));
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $this->handler->save(self::$key1, 'value');
 
@@ -123,7 +123,7 @@ public function testDelete()
         $this->assertFalse($this->handler->delete(self::$dummy));
     }
 
-    public function testDeleteMatchingPrefix()
+    public function testDeleteMatchingPrefix(): void
     {
         // Save 101 items to match on
         for ($i = 1; $i <= 101; $i++) {
@@ -141,7 +141,7 @@ public function testDeleteMatchingPrefix()
         $this->assertSame('88', $this->handler->getCacheInfo()['Keyspace']['db0']['keys']);
     }
 
-    public function testDeleteMatchingSuffix()
+    public function testDeleteMatchingSuffix(): void
     {
         // Save 101 items to match on
         for ($i = 1; $i <= 101; $i++) {
@@ -159,7 +159,7 @@ public function testDeleteMatchingSuffix()
         $this->assertSame('90', $this->handler->getCacheInfo()['Keyspace']['db0']['keys']);
     }
 
-    public function testClean()
+    public function testClean(): void
     {
         $this->handler->save(self::$key1, 1);
         $this->handler->save(self::$key2, 'value');
@@ -167,14 +167,14 @@ public function testClean()
         $this->assertTrue($this->handler->clean());
     }
 
-    public function testGetCacheInfo()
+    public function testGetCacheInfo(): void
     {
         $this->handler->save(self::$key1, 'value');
 
         $this->assertIsArray($this->handler->getCacheInfo());
     }
 
-    public function testIsSupported()
+    public function testIsSupported(): void
     {
         $this->assertTrue($this->handler->isSupported());
     }
diff --git a/tests/system/Cache/Handlers/RedisHandlerTest.php b/tests/system/Cache/Handlers/RedisHandlerTest.php
index 83a30a0de362..45f35df3f718 100644
--- a/tests/system/Cache/Handlers/RedisHandlerTest.php
+++ b/tests/system/Cache/Handlers/RedisHandlerTest.php
@@ -55,12 +55,12 @@ protected function tearDown(): void
         }
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $this->assertInstanceOf(RedisHandler::class, $this->handler);
     }
 
-    public function testDestruct()
+    public function testDestruct(): void
     {
         $this->handler = new RedisHandler($this->config);
         $this->handler->initialize();
@@ -74,7 +74,7 @@ public function testDestruct()
      *
      * @timeLimit 3.5
      */
-    public function testGet()
+    public function testGet(): void
     {
         $this->handler->save(self::$key1, 'value', 2);
 
@@ -91,7 +91,7 @@ public function testGet()
      *
      * @timeLimit 3.5
      */
-    public function testRemember()
+    public function testRemember(): void
     {
         $this->handler->remember(self::$key1, 2, static fn () => 'value');
 
@@ -102,12 +102,12 @@ public function testRemember()
         $this->assertNull($this->handler->get(self::$key1));
     }
 
-    public function testSave()
+    public function testSave(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value'));
     }
 
-    public function testSavePermanent()
+    public function testSavePermanent(): void
     {
         $this->assertTrue($this->handler->save(self::$key1, 'value', 0));
         $metaData = $this->handler->getMetaData(self::$key1);
@@ -119,7 +119,7 @@ public function testSavePermanent()
         $this->assertTrue($this->handler->delete(self::$key1));
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $this->handler->save(self::$key1, 'value');
 
@@ -127,7 +127,7 @@ public function testDelete()
         $this->assertFalse($this->handler->delete(self::$dummy));
     }
 
-    public function testDeleteMatchingPrefix()
+    public function testDeleteMatchingPrefix(): void
     {
         // Save 101 items to match on
         for ($i = 1; $i <= 101; $i++) {
@@ -147,7 +147,7 @@ public function testDeleteMatchingPrefix()
         $this->assertSame('keys=88', $dbInfo[0]);
     }
 
-    public function testDeleteMatchingSuffix()
+    public function testDeleteMatchingSuffix(): void
     {
         // Save 101 items to match on
         for ($i = 1; $i <= 101; $i++) {
@@ -167,7 +167,7 @@ public function testDeleteMatchingSuffix()
         $this->assertSame('keys=90', $dbInfo[0]);
     }
 
-    public function testIncrementAndDecrement()
+    public function testIncrementAndDecrement(): void
     {
         $this->handler->save('counter', 100);
 
@@ -184,14 +184,14 @@ public function testIncrementAndDecrement()
         $this->assertSame(140, $this->handler->get('counter'));
     }
 
-    public function testClean()
+    public function testClean(): void
     {
         $this->handler->save(self::$key1, 1);
 
         $this->assertTrue($this->handler->clean());
     }
 
-    public function testGetCacheInfo()
+    public function testGetCacheInfo(): void
     {
         $this->handler->save(self::$key1, 'value');
 
@@ -208,7 +208,7 @@ public function testGetMetadataNotNull(): void
         $this->assertIsArray($metadata);
     }
 
-    public function testIsSupported()
+    public function testIsSupported(): void
     {
         $this->assertTrue($this->handler->isSupported());
     }
diff --git a/tests/system/CodeIgniterTest.php b/tests/system/CodeIgniterTest.php
index ae88e6f2f3a1..a593fb279db3 100644
--- a/tests/system/CodeIgniterTest.php
+++ b/tests/system/CodeIgniterTest.php
@@ -59,7 +59,7 @@ protected function tearDown(): void
         $this->resetServices();
     }
 
-    public function testRunEmptyDefaultRoute()
+    public function testRunEmptyDefaultRoute(): void
     {
         $_SERVER['argv'] = ['index.php'];
         $_SERVER['argc'] = 1;
@@ -71,7 +71,7 @@ public function testRunEmptyDefaultRoute()
         $this->assertStringContainsString('Welcome to CodeIgniter', $output);
     }
 
-    public function testRunEmptyDefaultRouteReturnResponse()
+    public function testRunEmptyDefaultRouteReturnResponse(): void
     {
         $_SERVER['argv'] = ['index.php'];
         $_SERVER['argc'] = 1;
@@ -81,7 +81,7 @@ public function testRunEmptyDefaultRouteReturnResponse()
         $this->assertStringContainsString('Welcome to CodeIgniter', $response->getBody());
     }
 
-    public function testRunClosureRoute()
+    public function testRunClosureRoute(): void
     {
         $_SERVER['argv'] = ['index.php', 'pages/about'];
         $_SERVER['argc'] = 2;
@@ -90,7 +90,7 @@ public function testRunClosureRoute()
 
         // Inject mock router.
         $routes = Services::routes();
-        $routes->add('pages/(:segment)', static function ($segment) {
+        $routes->add('pages/(:segment)', static function ($segment): void {
             echo 'You want to see "' . esc($segment) . '" page.';
         });
         $router = Services::router($routes, Services::incomingrequest());
@@ -103,7 +103,7 @@ public function testRunClosureRoute()
         $this->assertStringContainsString('You want to see "about" page.', $output);
     }
 
-    public function testRun404Override()
+    public function testRun404Override(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -122,7 +122,7 @@ public function testRun404Override()
         $this->assertStringContainsString('Hello', $output);
     }
 
-    public function testRun404OverrideControllerReturnsResponse()
+    public function testRun404OverrideControllerReturnsResponse(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -141,7 +141,7 @@ public function testRun404OverrideControllerReturnsResponse()
         $this->assertStringContainsString('Oops', $output);
     }
 
-    public function testRun404OverrideReturnResponse()
+    public function testRun404OverrideReturnResponse(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -158,7 +158,7 @@ public function testRun404OverrideReturnResponse()
         $this->assertStringContainsString('Oops', $response->getBody());
     }
 
-    public function testRun404OverrideByClosure()
+    public function testRun404OverrideByClosure(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -166,7 +166,7 @@ public function testRun404OverrideByClosure()
         // Inject mock router.
         $routes = new RouteCollection(Services::locator(), new Modules());
         $routes->setAutoRoute(false);
-        $routes->set404Override(static function () {
+        $routes->set404Override(static function (): void {
             echo '404 Override by Closure.';
         });
         $router = Services::router($routes, Services::incomingrequest());
@@ -179,7 +179,7 @@ public function testRun404OverrideByClosure()
         $this->assertStringContainsString('404 Override by Closure.', $output);
     }
 
-    public function testControllersCanReturnString()
+    public function testControllersCanReturnString(): void
     {
         $_SERVER['argv'] = ['index.php', 'pages/about'];
         $_SERVER['argc'] = 2;
@@ -199,7 +199,7 @@ public function testControllersCanReturnString()
         $this->assertStringContainsString('You want to see "about" page.', $output);
     }
 
-    public function testControllersCanReturnResponseObject()
+    public function testControllersCanReturnResponseObject(): void
     {
         $_SERVER['argv'] = ['index.php', 'pages/about'];
         $_SERVER['argc'] = 2;
@@ -227,7 +227,7 @@ public function testControllersCanReturnResponseObject()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6358
      */
-    public function testControllersCanReturnDownloadResponseObject()
+    public function testControllersCanReturnDownloadResponseObject(): void
     {
         $_SERVER['argv'] = ['index.php', 'pages/about'];
         $_SERVER['argc'] = 2;
@@ -251,7 +251,7 @@ public function testControllersCanReturnDownloadResponseObject()
         $this->assertSame('some text', $output);
     }
 
-    public function testControllersRunFilterByClassName()
+    public function testControllersRunFilterByClassName(): void
     {
         $_SERVER['argv'] = ['index.php', 'pages/about'];
         $_SERVER['argc'] = 2;
@@ -274,7 +274,7 @@ public function testControllersRunFilterByClassName()
         $this->resetServices();
     }
 
-    public function testDisableControllerFilters()
+    public function testDisableControllerFilters(): void
     {
         $_SERVER['argv'] = ['index.php', 'pages/about'];
         $_SERVER['argc'] = 2;
@@ -301,7 +301,7 @@ public function testDisableControllerFilters()
         $this->resetServices();
     }
 
-    public function testResponseConfigEmpty()
+    public function testResponseConfigEmpty(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -311,7 +311,7 @@ public function testResponseConfigEmpty()
         $this->assertInstanceOf(Response::class, $response);
     }
 
-    public function testRoutesIsEmpty()
+    public function testRoutesIsEmpty(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -327,7 +327,7 @@ public function testRoutesIsEmpty()
         $this->assertStringContainsString('Welcome to CodeIgniter', $output);
     }
 
-    public function testTransfersCorrectHTTPVersion()
+    public function testTransfersCorrectHTTPVersion(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -343,7 +343,7 @@ public function testTransfersCorrectHTTPVersion()
         $this->assertSame('2.0', $response->getProtocolVersion());
     }
 
-    public function testSupportsHttp3()
+    public function testSupportsHttp3(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -359,7 +359,7 @@ public function testSupportsHttp3()
         $this->assertSame('3.0', $response->getProtocolVersion());
     }
 
-    public function testIgnoringErrorSuppressedByAt()
+    public function testIgnoringErrorSuppressedByAt(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -372,7 +372,7 @@ public function testIgnoringErrorSuppressedByAt()
         $this->assertStringContainsString('Welcome to CodeIgniter', $output);
     }
 
-    public function testRunForceSecure()
+    public function testRunForceSecure(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -397,7 +397,7 @@ public function testRunForceSecure()
         $this->assertSame('https://example.com/', $response->header('Location')->getValue());
     }
 
-    public function testRunRedirectionWithNamed()
+    public function testRunRedirectionWithNamed(): void
     {
         $_SERVER['argv'] = ['index.php', 'example'];
         $_SERVER['argc'] = 2;
@@ -406,7 +406,7 @@ public function testRunRedirectionWithNamed()
 
         // Inject mock router.
         $routes = Services::routes();
-        $routes->add('pages/named', static function () {
+        $routes->add('pages/named', static function (): void {
         }, ['as' => 'name']);
         $routes->addRedirect('example', 'name');
 
@@ -420,7 +420,7 @@ public function testRunRedirectionWithNamed()
         $this->assertSame('http://example.com/pages/named', $response->header('Location')->getValue());
     }
 
-    public function testRunRedirectionWithURI()
+    public function testRunRedirectionWithURI(): void
     {
         $_SERVER['argv'] = ['index.php', 'example'];
         $_SERVER['argc'] = 2;
@@ -429,7 +429,7 @@ public function testRunRedirectionWithURI()
 
         // Inject mock router.
         $routes = Services::routes();
-        $routes->add('pages/uri', static function () {
+        $routes->add('pages/uri', static function (): void {
         });
         $routes->addRedirect('example', 'pages/uri');
 
@@ -446,7 +446,7 @@ public function testRunRedirectionWithURI()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3041
      */
-    public function testRunRedirectionWithGET()
+    public function testRunRedirectionWithGET(): void
     {
         $_SERVER['argv'] = ['index.php', 'example'];
         $_SERVER['argc'] = 2;
@@ -472,7 +472,7 @@ public function testRunRedirectionWithGET()
         $this->assertSame(302, $response->getStatusCode());
     }
 
-    public function testRunRedirectionWithGETAndHTTPCode301()
+    public function testRunRedirectionWithGETAndHTTPCode301(): void
     {
         $_SERVER['argv'] = ['index.php', 'example'];
         $_SERVER['argc'] = 2;
@@ -496,7 +496,7 @@ public function testRunRedirectionWithGETAndHTTPCode301()
         $this->assertSame(301, $response->getStatusCode());
     }
 
-    public function testRunRedirectionWithPOSTAndHTTPCode301()
+    public function testRunRedirectionWithPOSTAndHTTPCode301(): void
     {
         $_SERVER['argv'] = ['index.php', 'example'];
         $_SERVER['argc'] = 2;
@@ -520,7 +520,7 @@ public function testRunRedirectionWithPOSTAndHTTPCode301()
         $this->assertSame(301, $response->getStatusCode());
     }
 
-    public function testStoresPreviousURL()
+    public function testStoresPreviousURL(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -537,7 +537,7 @@ public function testStoresPreviousURL()
         $this->assertSame('http://example.com/index.php', $_SESSION['_ci_previous_url']);
     }
 
-    public function testNotStoresPreviousURL()
+    public function testNotStoresPreviousURL(): void
     {
         $_SERVER['argv'] = ['index.php', 'example'];
         $_SERVER['argc'] = 2;
@@ -560,7 +560,7 @@ public function testNotStoresPreviousURL()
         $this->assertArrayNotHasKey('_ci_previous_url', $_SESSION);
     }
 
-    public function testNotStoresPreviousURLByCheckingContentType()
+    public function testNotStoresPreviousURLByCheckingContentType(): void
     {
         $_SERVER['argv'] = ['index.php', 'image'];
         $_SERVER['argc'] = 2;
@@ -589,7 +589,7 @@ public function testNotStoresPreviousURLByCheckingContentType()
      * Can't use static::tearDownAfterClass. This will cause a buffer exception
      * need improve
      */
-    public function testRunDefaultRoute()
+    public function testRunDefaultRoute(): void
     {
         $_SERVER['argv'] = ['index.php', '/'];
         $_SERVER['argc'] = 2;
@@ -601,7 +601,7 @@ public function testRunDefaultRoute()
         $this->assertStringContainsString('Welcome to CodeIgniter', $output);
     }
 
-    public function testRunCLIRoute()
+    public function testRunCLIRoute(): void
     {
         $_SERVER['argv'] = ['index.php', 'cli'];
         $_SERVER['argc'] = 2;
@@ -620,7 +620,7 @@ public function testRunCLIRoute()
         $this->assertStringContainsString('Method Not Allowed', $output);
     }
 
-    public function testSpoofRequestMethodCanUsePUT()
+    public function testSpoofRequestMethodCanUsePUT(): void
     {
         $_SERVER['argv'] = ['index.php'];
         $_SERVER['argc'] = 1;
@@ -644,7 +644,7 @@ public function testSpoofRequestMethodCanUsePUT()
         $this->assertSame('put', Services::incomingrequest()->getMethod());
     }
 
-    public function testSpoofRequestMethodCannotUseGET()
+    public function testSpoofRequestMethodCannotUseGET(): void
     {
         $_SERVER['argv'] = ['index.php'];
         $_SERVER['argc'] = 1;
@@ -671,7 +671,7 @@ public function testSpoofRequestMethodCannotUseGET()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6281
      */
-    public function testPageCacheSendSecureHeaders()
+    public function testPageCacheSendSecureHeaders(): void
     {
         // Suppress command() output
         CITestStreamFilter::registration();
@@ -735,7 +735,7 @@ public function testPageCacheSendSecureHeaders()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/pull/6410
      */
-    public function testPageCacheWithCacheQueryString($cacheQueryStringValue, int $expectedPagesInCache, array $testingUrls)
+    public function testPageCacheWithCacheQueryString($cacheQueryStringValue, int $expectedPagesInCache, array $testingUrls): void
     {
         // Suppress command() output
         CITestStreamFilter::registration();
diff --git a/tests/system/Commands/BaseCommandTest.php b/tests/system/Commands/BaseCommandTest.php
index 068a8d832924..c486edb55679 100644
--- a/tests/system/Commands/BaseCommandTest.php
+++ b/tests/system/Commands/BaseCommandTest.php
@@ -31,28 +31,28 @@ protected function setUp(): void
         $this->logger = Services::logger();
     }
 
-    public function testMagicIssetTrue()
+    public function testMagicIssetTrue(): void
     {
         $command = new AppInfo($this->logger, service('commands'));
 
         $this->assertTrue(isset($command->group));
     }
 
-    public function testMagicIssetFalse()
+    public function testMagicIssetFalse(): void
     {
         $command = new AppInfo($this->logger, service('commands'));
 
         $this->assertFalse(isset($command->foobar));
     }
 
-    public function testMagicGet()
+    public function testMagicGet(): void
     {
         $command = new AppInfo($this->logger, service('commands'));
 
         $this->assertSame('demo', $command->group);
     }
 
-    public function testMagicGetMissing()
+    public function testMagicGetMissing(): void
     {
         $command = new AppInfo($this->logger, service('commands'));
 
diff --git a/tests/system/Commands/ClearCacheTest.php b/tests/system/Commands/ClearCacheTest.php
index 1ada8b55f3ca..52afbfabd4d1 100644
--- a/tests/system/Commands/ClearCacheTest.php
+++ b/tests/system/Commands/ClearCacheTest.php
@@ -33,14 +33,14 @@ protected function setUp(): void
         Services::injectMock('cache', CacheFactory::getHandler(config('Cache')));
     }
 
-    public function testClearCacheInvalidHandler()
+    public function testClearCacheInvalidHandler(): void
     {
         command('cache:clear junk');
 
         $this->assertStringContainsString('junk is not a valid cache handler.', $this->getStreamFilterBuffer());
     }
 
-    public function testClearCacheWorks()
+    public function testClearCacheWorks(): void
     {
         cache()->save('foo', 'bar');
         $this->assertSame('bar', cache('foo'));
diff --git a/tests/system/Commands/ClearDebugbarTest.php b/tests/system/Commands/ClearDebugbarTest.php
index 4a398e4f4016..b8f6fa13e535 100644
--- a/tests/system/Commands/ClearDebugbarTest.php
+++ b/tests/system/Commands/ClearDebugbarTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void
         $this->time = time();
     }
 
-    protected function createDummyDebugbarJson()
+    protected function createDummyDebugbarJson(): void
     {
         $time = $this->time;
         $path = WRITEPATH . 'debugbar' . DIRECTORY_SEPARATOR . "debugbar_{$time}.json";
@@ -46,7 +46,7 @@ protected function createDummyDebugbarJson()
         }
     }
 
-    public function testClearDebugbarWorks()
+    public function testClearDebugbarWorks(): void
     {
         // test clean debugbar dir
         $this->assertFileDoesNotExist(WRITEPATH . 'debugbar' . DIRECTORY_SEPARATOR . "debugbar_{$this->time}.json");
diff --git a/tests/system/Commands/ClearLogsTest.php b/tests/system/Commands/ClearLogsTest.php
index daeb0461acec..406393020343 100644
--- a/tests/system/Commands/ClearLogsTest.php
+++ b/tests/system/Commands/ClearLogsTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
         $this->date = date('Y-m-d', strtotime('+1 year'));
     }
 
-    protected function createDummyLogFiles()
+    protected function createDummyLogFiles(): void
     {
         $date = $this->date;
         $path = WRITEPATH . 'logs' . DIRECTORY_SEPARATOR . "log-{$date}.log";
@@ -49,7 +49,7 @@ protected function createDummyLogFiles()
         }
     }
 
-    public function testClearLogsWorks()
+    public function testClearLogsWorks(): void
     {
         // test clean logs dir
         $this->assertFileDoesNotExist(WRITEPATH . 'logs' . DIRECTORY_SEPARATOR . "log-{$this->date}.log");
diff --git a/tests/system/Commands/CommandGeneratorTest.php b/tests/system/Commands/CommandGeneratorTest.php
index d72ba1b36aab..64ab5a21d2d9 100644
--- a/tests/system/Commands/CommandGeneratorTest.php
+++ b/tests/system/Commands/CommandGeneratorTest.php
@@ -46,7 +46,7 @@ protected function getFileContents(string $filepath): string
         return file_get_contents($filepath) ?: '';
     }
 
-    public function testGenerateCommand()
+    public function testGenerateCommand(): void
     {
         command('make:command deliver');
         $file = APPPATH . 'Commands/Deliver.php';
@@ -56,7 +56,7 @@ public function testGenerateCommand()
         $this->assertStringContainsString('protected $name = \'command:name\';', $contents);
     }
 
-    public function testGenerateCommandWithOptionCommand()
+    public function testGenerateCommandWithOptionCommand(): void
     {
         command('make:command deliver -command clear:sessions');
         $file = APPPATH . 'Commands/Deliver.php';
@@ -66,7 +66,7 @@ public function testGenerateCommandWithOptionCommand()
         $this->assertStringContainsString('protected $usage = \'clear:sessions [arguments] [options]\';', $contents);
     }
 
-    public function testGenerateCommandWithOptionTypeBasic()
+    public function testGenerateCommandWithOptionTypeBasic(): void
     {
         command('make:command deliver -type basic');
         $file = APPPATH . 'Commands/Deliver.php';
@@ -76,7 +76,7 @@ public function testGenerateCommandWithOptionTypeBasic()
         $this->assertStringContainsString('protected $name = \'command:name\';', $contents);
     }
 
-    public function testGenerateCommandWithOptionTypeGenerator()
+    public function testGenerateCommandWithOptionTypeGenerator(): void
     {
         command('make:command deliver -type generator');
         $file = APPPATH . 'Commands/Deliver.php';
@@ -86,7 +86,7 @@ public function testGenerateCommandWithOptionTypeGenerator()
         $this->assertStringContainsString('protected $name = \'command:name\';', $contents);
     }
 
-    public function testGenerateCommandWithOptionGroup()
+    public function testGenerateCommandWithOptionGroup(): void
     {
         command('make:command deliver -group Deliverables');
         $file = APPPATH . 'Commands/Deliver.php';
@@ -97,7 +97,7 @@ public function testGenerateCommandWithOptionGroup()
         $this->assertStringContainsString('protected $group = \'Deliverables\';', $contents);
     }
 
-    public function testGenerateCommandWithOptionSuffix()
+    public function testGenerateCommandWithOptionSuffix(): void
     {
         command('make:command publish -suffix');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
diff --git a/tests/system/Commands/CommandTest.php b/tests/system/Commands/CommandTest.php
index 1101e08ef5b6..90da337c11a0 100644
--- a/tests/system/Commands/CommandTest.php
+++ b/tests/system/Commands/CommandTest.php
@@ -45,7 +45,7 @@ protected function getBuffer()
         return $this->getStreamFilterBuffer();
     }
 
-    public function testListCommands()
+    public function testListCommands(): void
     {
         command('list');
 
@@ -54,7 +54,7 @@ public function testListCommands()
         $this->assertStringContainsString('Displays basic usage information.', $this->getBuffer());
     }
 
-    public function testListCommandsSimple()
+    public function testListCommandsSimple(): void
     {
         command('list --simple');
 
@@ -62,13 +62,13 @@ public function testListCommandsSimple()
         $this->assertStringNotContainsString('Lists the available commands.', $this->getBuffer());
     }
 
-    public function testCustomCommand()
+    public function testCustomCommand(): void
     {
         command('app:info');
         $this->assertStringContainsString('CI Version:', $this->getBuffer());
     }
 
-    public function testShowError()
+    public function testShowError(): void
     {
         command('app:info');
         $commands = $this->commands->getCommands();
@@ -78,7 +78,7 @@ public function testShowError()
         $this->assertStringContainsString('Displays basic usage information.', $this->getBuffer());
     }
 
-    public function testCommandCall()
+    public function testCommandCall(): void
     {
         command('app:info');
         $commands = $this->commands->getCommands();
@@ -88,13 +88,13 @@ public function testCommandCall()
         $this->assertStringContainsString('Invalid "background" color:', $this->getBuffer());
     }
 
-    public function testAbstractCommand()
+    public function testAbstractCommand(): void
     {
         command('app:pablo');
         $this->assertStringContainsString('not found', $this->getBuffer());
     }
 
-    public function testNamespacesCommand()
+    public function testNamespacesCommand(): void
     {
         command('namespaces');
 
@@ -103,13 +103,13 @@ public function testNamespacesCommand()
         $this->assertStringContainsString('| Yes', $this->getBuffer());
     }
 
-    public function testInexistentCommandWithNoAlternatives()
+    public function testInexistentCommandWithNoAlternatives(): void
     {
         command('app:oops');
         $this->assertStringContainsString('Command "app:oops" not found', $this->getBuffer());
     }
 
-    public function testInexistentCommandsButWithOneAlternative()
+    public function testInexistentCommandsButWithOneAlternative(): void
     {
         command('namespace');
 
@@ -118,7 +118,7 @@ public function testInexistentCommandsButWithOneAlternative()
         $this->assertStringContainsString('namespaces', $this->getBuffer());
     }
 
-    public function testInexistentCommandsButWithManyAlternatives()
+    public function testInexistentCommandsButWithManyAlternatives(): void
     {
         command('clear');
 
@@ -130,7 +130,7 @@ public function testInexistentCommandsButWithManyAlternatives()
     /**
      * @dataProvider commandArgsProvider
      */
-    public function testCommandParsesArgsCorrectly(string $input, array $expected)
+    public function testCommandParsesArgsCorrectly(string $input, array $expected): void
     {
         ParamsReveal::$args = null;
         command($input);
diff --git a/tests/system/Commands/ConfigGeneratorTest.php b/tests/system/Commands/ConfigGeneratorTest.php
index 08ad58a25d9c..f4036a24e65e 100644
--- a/tests/system/Commands/ConfigGeneratorTest.php
+++ b/tests/system/Commands/ConfigGeneratorTest.php
@@ -32,13 +32,13 @@ protected function tearDown(): void
         }
     }
 
-    public function testGenerateConfig()
+    public function testGenerateConfig(): void
     {
         command('make:config auth');
         $this->assertFileExists(APPPATH . 'Config/Auth.php');
     }
 
-    public function testGenerateConfigWithOptionSuffix()
+    public function testGenerateConfigWithOptionSuffix(): void
     {
         command('make:config auth -suffix');
         $this->assertFileExists(APPPATH . 'Config/AuthConfig.php');
diff --git a/tests/system/Commands/ConfigurableSortImportsTest.php b/tests/system/Commands/ConfigurableSortImportsTest.php
index 6e98a73cd62c..0bc5b9498c17 100644
--- a/tests/system/Commands/ConfigurableSortImportsTest.php
+++ b/tests/system/Commands/ConfigurableSortImportsTest.php
@@ -23,7 +23,7 @@ final class ConfigurableSortImportsTest extends CIUnitTestCase
 {
     use StreamFilterTrait;
 
-    public function testPublishLanguageWithoutOptions()
+    public function testPublishLanguageWithoutOptions(): void
     {
         command('publish:language');
 
@@ -36,7 +36,7 @@ public function testPublishLanguageWithoutOptions()
         }
     }
 
-    public function testEnabledSortImportsWillDisruptLanguageFilePublish()
+    public function testEnabledSortImportsWillDisruptLanguageFilePublish(): void
     {
         command('publish:language --lang es');
 
@@ -53,7 +53,7 @@ public function testEnabledSortImportsWillDisruptLanguageFilePublish()
         }
     }
 
-    public function testDisabledSortImportsWillNotAffectLanguageFilesPublish()
+    public function testDisabledSortImportsWillNotAffectLanguageFilesPublish(): void
     {
         command('publish:language --lang ar --sort off');
 
diff --git a/tests/system/Commands/ControllerGeneratorTest.php b/tests/system/Commands/ControllerGeneratorTest.php
index 9ff4d027b45c..9567280f1d34 100644
--- a/tests/system/Commands/ControllerGeneratorTest.php
+++ b/tests/system/Commands/ControllerGeneratorTest.php
@@ -41,7 +41,7 @@ protected function getFileContents(string $filepath): string
         return file_get_contents($filepath) ?: '';
     }
 
-    public function testGenerateController()
+    public function testGenerateController(): void
     {
         command('make:controller user');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -50,7 +50,7 @@ public function testGenerateController()
         $this->assertStringContainsString('extends BaseController', $this->getFileContents($file));
     }
 
-    public function testGenerateControllerWithOptionBare()
+    public function testGenerateControllerWithOptionBare(): void
     {
         command('make:controller blog -bare');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -59,7 +59,7 @@ public function testGenerateControllerWithOptionBare()
         $this->assertStringContainsString('extends Controller', $this->getFileContents($file));
     }
 
-    public function testGenerateControllerWithOptionRestful()
+    public function testGenerateControllerWithOptionRestful(): void
     {
         command('make:controller order -restful');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -68,7 +68,7 @@ public function testGenerateControllerWithOptionRestful()
         $this->assertStringContainsString('extends ResourceController', $this->getFileContents($file));
     }
 
-    public function testGenerateControllerWithOptionRestfulPresenter()
+    public function testGenerateControllerWithOptionRestfulPresenter(): void
     {
         command('make:controller pay -restful presenter');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -77,7 +77,7 @@ public function testGenerateControllerWithOptionRestfulPresenter()
         $this->assertStringContainsString('extends ResourcePresenter', $this->getFileContents($file));
     }
 
-    public function testGenerateControllerWithOptionSuffix()
+    public function testGenerateControllerWithOptionSuffix(): void
     {
         command('make:controller dashboard -suffix');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
diff --git a/tests/system/Commands/CreateDatabaseTest.php b/tests/system/Commands/CreateDatabaseTest.php
index 7ee07a2d936d..a1468f1184dc 100644
--- a/tests/system/Commands/CreateDatabaseTest.php
+++ b/tests/system/Commands/CreateDatabaseTest.php
@@ -67,7 +67,7 @@ protected function getBuffer()
         return $this->getStreamFilterBuffer();
     }
 
-    public function testCreateDatabase()
+    public function testCreateDatabase(): void
     {
         if ($this->connection instanceof OCI8Connection) {
             $this->markTestSkipped('Needs to run on non-OCI8 drivers.');
@@ -77,7 +77,7 @@ public function testCreateDatabase()
         $this->assertStringContainsString('successfully created.', $this->getBuffer());
     }
 
-    public function testSqliteDatabaseDuplicated()
+    public function testSqliteDatabaseDuplicated(): void
     {
         if (! $this->connection instanceof SQLite3Connection) {
             $this->markTestSkipped('Needs to run on SQLite3.');
@@ -90,7 +90,7 @@ public function testSqliteDatabaseDuplicated()
         $this->assertStringContainsString('already exists.', $this->getBuffer());
     }
 
-    public function testOtherDriverDuplicatedDatabase()
+    public function testOtherDriverDuplicatedDatabase(): void
     {
         if ($this->connection instanceof SQLite3Connection || $this->connection instanceof OCI8Connection) {
             $this->markTestSkipped('Needs to run on non-SQLite3 and non-OCI8 drivers.');
diff --git a/tests/system/Commands/DatabaseCommandsTest.php b/tests/system/Commands/DatabaseCommandsTest.php
index 9d025d38517b..f0832f429efd 100644
--- a/tests/system/Commands/DatabaseCommandsTest.php
+++ b/tests/system/Commands/DatabaseCommandsTest.php
@@ -40,7 +40,7 @@ protected function clearBuffer(): void
         $this->resetStreamFilterBuffer();
     }
 
-    public function testMigrate()
+    public function testMigrate(): void
     {
         command('migrate --all');
         $this->assertStringContainsString('Migrations complete.', $this->getBuffer());
@@ -51,7 +51,7 @@ public function testMigrate()
         $this->assertStringContainsString('Migrations complete.', $this->getBuffer());
     }
 
-    public function testMigrateRollback()
+    public function testMigrateRollback(): void
     {
         command('migrate --all -g tests');
         $this->clearBuffer();
@@ -60,7 +60,7 @@ public function testMigrateRollback()
         $this->assertStringContainsString('Done rolling back migrations.', $this->getBuffer());
     }
 
-    public function testMigrateRefresh()
+    public function testMigrateRefresh(): void
     {
         command('migrate --all');
         $this->clearBuffer();
@@ -69,7 +69,7 @@ public function testMigrateRefresh()
         $this->assertStringContainsString('Migrations complete.', $this->getBuffer());
     }
 
-    public function testMigrateStatus()
+    public function testMigrateStatus(): void
     {
         command('migrate --all');
         $this->clearBuffer();
@@ -80,7 +80,7 @@ public function testMigrateStatus()
         $this->assertStringContainsString('Filename', $this->getBuffer());
     }
 
-    public function testSeed()
+    public function testSeed(): void
     {
         command('migrate --all');
         $this->clearBuffer();
diff --git a/tests/system/Commands/EntityGeneratorTest.php b/tests/system/Commands/EntityGeneratorTest.php
index 5d14ddfeaf06..47146b027056 100644
--- a/tests/system/Commands/EntityGeneratorTest.php
+++ b/tests/system/Commands/EntityGeneratorTest.php
@@ -36,13 +36,13 @@ protected function tearDown(): void
         }
     }
 
-    public function testGenerateEntity()
+    public function testGenerateEntity(): void
     {
         command('make:entity user');
         $this->assertFileExists(APPPATH . 'Entities/User.php');
     }
 
-    public function testGenerateEntityWithOptionSuffix()
+    public function testGenerateEntityWithOptionSuffix(): void
     {
         command('make:entity user -suffix');
         $this->assertFileExists(APPPATH . 'Entities/UserEntity.php');
diff --git a/tests/system/Commands/EnvironmentCommandTest.php b/tests/system/Commands/EnvironmentCommandTest.php
index 84c796ecb669..4b7a4a473dfa 100644
--- a/tests/system/Commands/EnvironmentCommandTest.php
+++ b/tests/system/Commands/EnvironmentCommandTest.php
@@ -72,7 +72,7 @@ public function testProvidingUnknownEnvGivesErrorMessage(): void
         $this->assertStringContainsString('Invalid environment type "foobar".', $this->getStreamFilterBuffer());
     }
 
-    public function testDefaultShippedEnvIsMissing()
+    public function testDefaultShippedEnvIsMissing(): void
     {
         rename(ROOTPATH . 'env', ROOTPATH . 'lostenv');
         command('env development');
diff --git a/tests/system/Commands/FilterCheckTest.php b/tests/system/Commands/FilterCheckTest.php
index 4959afb0826c..a0b74099f818 100644
--- a/tests/system/Commands/FilterCheckTest.php
+++ b/tests/system/Commands/FilterCheckTest.php
@@ -40,7 +40,7 @@ protected function getBuffer()
         return $this->getStreamFilterBuffer();
     }
 
-    public function testFilterCheckDefinedRoute()
+    public function testFilterCheckDefinedRoute(): void
     {
         command('filter:check get /');
 
@@ -50,7 +50,7 @@ public function testFilterCheckDefinedRoute()
         );
     }
 
-    public function testFilterCheckInvalidRoute()
+    public function testFilterCheckInvalidRoute(): void
     {
         command('filter:check put product/123');
 
diff --git a/tests/system/Commands/FilterGeneratorTest.php b/tests/system/Commands/FilterGeneratorTest.php
index 148c7031ce3e..7f697e21c9dc 100644
--- a/tests/system/Commands/FilterGeneratorTest.php
+++ b/tests/system/Commands/FilterGeneratorTest.php
@@ -32,13 +32,13 @@ protected function tearDown(): void
         }
     }
 
-    public function testGenerateFilter()
+    public function testGenerateFilter(): void
     {
         command('make:filter admin');
         $this->assertFileExists(APPPATH . 'Filters/Admin.php');
     }
 
-    public function testGenerateFilterWithOptionSuffix()
+    public function testGenerateFilterWithOptionSuffix(): void
     {
         command('make:filter admin -suffix');
         $this->assertFileExists(APPPATH . 'Filters/AdminFilter.php');
diff --git a/tests/system/Commands/GenerateKeyTest.php b/tests/system/Commands/GenerateKeyTest.php
index 6c313e648cff..dd0f8bc91f0a 100644
--- a/tests/system/Commands/GenerateKeyTest.php
+++ b/tests/system/Commands/GenerateKeyTest.php
@@ -62,13 +62,13 @@ protected function getBuffer(): string
         return $this->getStreamFilterBuffer();
     }
 
-    protected function resetEnvironment()
+    protected function resetEnvironment(): void
     {
         putenv('encryption.key');
         unset($_ENV['encryption.key'], $_SERVER['encryption.key']);
     }
 
-    public function testGenerateKeyShowsEncodedKey()
+    public function testGenerateKeyShowsEncodedKey(): void
     {
         command('key:generate --show');
         $this->assertStringContainsString('hex2bin:', $this->getBuffer());
@@ -84,7 +84,7 @@ public function testGenerateKeyShowsEncodedKey()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testGenerateKeyCreatesNewKey()
+    public function testGenerateKeyCreatesNewKey(): void
     {
         command('key:generate');
         $this->assertStringContainsString('successfully set.', $this->getBuffer());
@@ -102,7 +102,7 @@ public function testGenerateKeyCreatesNewKey()
         $this->assertStringContainsString('hex2bin:', file_get_contents($this->envPath));
     }
 
-    public function testDefaultShippedEnvIsMissing()
+    public function testDefaultShippedEnvIsMissing(): void
     {
         rename(ROOTPATH . 'env', ROOTPATH . 'lostenv');
         command('key:generate');
@@ -115,7 +115,7 @@ public function testDefaultShippedEnvIsMissing()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6838
      */
-    public function testKeyGenerateWhenKeyIsMissingInDotEnvFile()
+    public function testKeyGenerateWhenKeyIsMissingInDotEnvFile(): void
     {
         file_put_contents($this->envPath, '');
 
@@ -125,7 +125,7 @@ public function testKeyGenerateWhenKeyIsMissingInDotEnvFile()
         $this->assertSame("\nencryption.key = " . env('encryption.key'), file_get_contents($this->envPath));
     }
 
-    public function testKeyGenerateWhenNewHexKeyIsSubsequentlyCommentedOut()
+    public function testKeyGenerateWhenNewHexKeyIsSubsequentlyCommentedOut(): void
     {
         command('key:generate');
         $key = env('encryption.key', '');
@@ -143,7 +143,7 @@ public function testKeyGenerateWhenNewHexKeyIsSubsequentlyCommentedOut()
         $this->assertNotSame($key, env('encryption.key', $key), 'Failed replacing the commented out key.');
     }
 
-    public function testKeyGenerateWhenNewBase64KeyIsSubsequentlyCommentedOut()
+    public function testKeyGenerateWhenNewBase64KeyIsSubsequentlyCommentedOut(): void
     {
         command('key:generate --prefix base64');
         $key = env('encryption.key', '');
diff --git a/tests/system/Commands/GeneratorsTest.php b/tests/system/Commands/GeneratorsTest.php
index d02fd2eea78b..2e5162b074a8 100644
--- a/tests/system/Commands/GeneratorsTest.php
+++ b/tests/system/Commands/GeneratorsTest.php
@@ -23,7 +23,7 @@ final class GeneratorsTest extends CIUnitTestCase
 {
     use StreamFilterTrait;
 
-    public function testGenerateFileCreated()
+    public function testGenerateFileCreated(): void
     {
         command('make:seeder categories');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -33,7 +33,7 @@ public function testGenerateFileCreated()
         }
     }
 
-    public function testGenerateFileExists()
+    public function testGenerateFileExists(): void
     {
         command('make:filter items');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -46,7 +46,7 @@ public function testGenerateFileExists()
         }
     }
 
-    public function testGenerateFileOverwritten()
+    public function testGenerateFileOverwritten(): void
     {
         command('make:controller products');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -59,7 +59,7 @@ public function testGenerateFileOverwritten()
         }
     }
 
-    public function testGenerateFileFailsOnUnwritableDirectory()
+    public function testGenerateFileFailsOnUnwritableDirectory(): void
     {
         if (is_windows()) {
             $this->markTestSkipped('chmod does not work as expected on Windows');
@@ -73,13 +73,13 @@ public function testGenerateFileFailsOnUnwritableDirectory()
         chmod(APPPATH . 'Filters', 0755);
     }
 
-    public function testGenerateFailsOnUndefinedNamespace()
+    public function testGenerateFailsOnUndefinedNamespace(): void
     {
         command('make:model cars -namespace CodeIgnite');
         $this->assertStringContainsString('Namespace "CodeIgnite" is not defined.', $this->getStreamFilterBuffer());
     }
 
-    public function testGenerateFileInSubfolders()
+    public function testGenerateFileInSubfolders(): void
     {
         command('make:controller admin/user');
         $file = APPPATH . 'Controllers/Admin/User.php';
diff --git a/tests/system/Commands/HelpCommandTest.php b/tests/system/Commands/HelpCommandTest.php
index 3b56b3c92130..c51a286e5bbf 100644
--- a/tests/system/Commands/HelpCommandTest.php
+++ b/tests/system/Commands/HelpCommandTest.php
@@ -28,7 +28,7 @@ protected function getBuffer()
         return $this->getStreamFilterBuffer();
     }
 
-    public function testHelpCommand()
+    public function testHelpCommand(): void
     {
         command('help');
 
@@ -37,25 +37,25 @@ public function testHelpCommand()
         $this->assertStringContainsString('command_name', $this->getBuffer());
     }
 
-    public function testHelpCommandWithMissingUsage()
+    public function testHelpCommandWithMissingUsage(): void
     {
         command('help app:info');
         $this->assertStringContainsString('app:info [arguments]', $this->getBuffer());
     }
 
-    public function testHelpCommandOnSpecificCommand()
+    public function testHelpCommandOnSpecificCommand(): void
     {
         command('help cache:clear');
         $this->assertStringContainsString('Clears the current system caches.', $this->getBuffer());
     }
 
-    public function testHelpCommandOnInexistentCommand()
+    public function testHelpCommandOnInexistentCommand(): void
     {
         command('help fixme');
         $this->assertStringContainsString('Command "fixme" not found', $this->getBuffer());
     }
 
-    public function testHelpCommandOnInexistentCommandButWithAlternatives()
+    public function testHelpCommandOnInexistentCommandButWithAlternatives(): void
     {
         command('help clear');
         $this->assertStringContainsString('Command "clear" not found.', $this->getBuffer());
diff --git a/tests/system/Commands/InfoCacheTest.php b/tests/system/Commands/InfoCacheTest.php
index 91312a6e36cd..fc0337087b3a 100644
--- a/tests/system/Commands/InfoCacheTest.php
+++ b/tests/system/Commands/InfoCacheTest.php
@@ -44,7 +44,7 @@ protected function getBuffer()
         return $this->getStreamFilterBuffer();
     }
 
-    public function testInfoCacheErrorsOnInvalidHandler()
+    public function testInfoCacheErrorsOnInvalidHandler(): void
     {
         config('Cache')->handler = 'redis';
         cache()->save('foo', 'bar');
@@ -53,7 +53,7 @@ public function testInfoCacheErrorsOnInvalidHandler()
         $this->assertStringContainsString('This command only supports the file cache handler.', $this->getBuffer());
     }
 
-    public function testInfoCacheCanSeeFoo()
+    public function testInfoCacheCanSeeFoo(): void
     {
         cache()->save('foo', 'bar');
         command('cache:info');
@@ -61,7 +61,7 @@ public function testInfoCacheCanSeeFoo()
         $this->assertStringContainsString('foo', $this->getBuffer());
     }
 
-    public function testInfoCacheCanSeeTable()
+    public function testInfoCacheCanSeeTable(): void
     {
         command('cache:info');
 
@@ -71,7 +71,7 @@ public function testInfoCacheCanSeeTable()
         $this->assertStringContainsString('Date', $this->getBuffer());
     }
 
-    public function testInfoCacheCannotSeeFoo()
+    public function testInfoCacheCannotSeeFoo(): void
     {
         cache()->delete('foo');
         command('cache:info');
diff --git a/tests/system/Commands/MigrationGeneratorTest.php b/tests/system/Commands/MigrationGeneratorTest.php
index b07c69726791..890c36c56fe7 100644
--- a/tests/system/Commands/MigrationGeneratorTest.php
+++ b/tests/system/Commands/MigrationGeneratorTest.php
@@ -32,25 +32,25 @@ protected function tearDown(): void
         }
     }
 
-    public function testGenerateMigration()
+    public function testGenerateMigration(): void
     {
         command('make:migration database');
         $this->assertStringContainsString('_Database.php', $this->getStreamFilterBuffer());
     }
 
-    public function testGenerateMigrationWithOptionSession()
+    public function testGenerateMigrationWithOptionSession(): void
     {
         command('make:migration -session');
         $this->assertStringContainsString('_CreateCiSessionsTable.php', $this->getStreamFilterBuffer());
     }
 
-    public function testGenerateMigrationWithOptionTable()
+    public function testGenerateMigrationWithOptionTable(): void
     {
         command('make:migration -session -table logger');
         $this->assertStringContainsString('_CreateLoggerTable.php', $this->getStreamFilterBuffer());
     }
 
-    public function testGenerateMigrationWithOptionSuffix()
+    public function testGenerateMigrationWithOptionSuffix(): void
     {
         command('make:migration database -suffix');
         $this->assertStringContainsString('_DatabaseMigration.php', $this->getStreamFilterBuffer());
diff --git a/tests/system/Commands/ModelGeneratorTest.php b/tests/system/Commands/ModelGeneratorTest.php
index 0e193d62702c..e6ca050d553b 100644
--- a/tests/system/Commands/ModelGeneratorTest.php
+++ b/tests/system/Commands/ModelGeneratorTest.php
@@ -44,7 +44,7 @@ private function getFileContent(string $filepath): string
         return file_get_contents($filepath) ?: '';
     }
 
-    public function testGenerateModel()
+    public function testGenerateModel(): void
     {
         command('make:model user --table users');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -56,7 +56,7 @@ public function testGenerateModel()
         $this->assertStringContainsString('protected $returnType       = \'array\';', $this->getFileContent($file));
     }
 
-    public function testGenerateModelWithOptionTable()
+    public function testGenerateModelWithOptionTable(): void
     {
         command('make:model cars -table utilisateur');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -65,7 +65,7 @@ public function testGenerateModelWithOptionTable()
         $this->assertStringContainsString('protected $table            = \'utilisateur\';', $this->getFileContent($file));
     }
 
-    public function testGenerateModelWithOptionDBGroup()
+    public function testGenerateModelWithOptionDBGroup(): void
     {
         command('make:model user -dbgroup testing');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -74,7 +74,7 @@ public function testGenerateModelWithOptionDBGroup()
         $this->assertStringContainsString('protected $DBGroup          = \'testing\';', $this->getFileContent($file));
     }
 
-    public function testGenerateModelWithOptionReturnArray()
+    public function testGenerateModelWithOptionReturnArray(): void
     {
         command('make:model user --return array');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -83,7 +83,7 @@ public function testGenerateModelWithOptionReturnArray()
         $this->assertStringContainsString('protected $returnType       = \'array\';', $this->getFileContent($file));
     }
 
-    public function testGenerateModelWithOptionReturnObject()
+    public function testGenerateModelWithOptionReturnObject(): void
     {
         command('make:model user --return object');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -92,7 +92,7 @@ public function testGenerateModelWithOptionReturnObject()
         $this->assertStringContainsString('protected $returnType       = \'object\';', $this->getFileContent($file));
     }
 
-    public function testGenerateModelWithOptionReturnEntity()
+    public function testGenerateModelWithOptionReturnEntity(): void
     {
         command('make:model user --return entity');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -118,7 +118,7 @@ public function testGenerateModelWithOptionReturnEntity()
         }
     }
 
-    public function testGenerateModelWithOptionSuffix()
+    public function testGenerateModelWithOptionSuffix(): void
     {
         command('make:model user --suffix --return entity');
 
@@ -136,7 +136,7 @@ public function testGenerateModelWithOptionSuffix()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5050
      */
-    public function testGenerateModelWithSuffixAndMixedPascalCasedName()
+    public function testGenerateModelWithSuffixAndMixedPascalCasedName(): void
     {
         command('make:model MyTable --suffix --return entity');
 
diff --git a/tests/system/Commands/PublishCommandTest.php b/tests/system/Commands/PublishCommandTest.php
index a56e7661505a..b176a03c42c5 100644
--- a/tests/system/Commands/PublishCommandTest.php
+++ b/tests/system/Commands/PublishCommandTest.php
@@ -31,7 +31,7 @@ protected function tearDown(): void
         TestPublisher::setResult(true);
     }
 
-    public function testDefault()
+    public function testDefault(): void
     {
         command('publish');
 
@@ -42,7 +42,7 @@ public function testDefault()
         ]), $this->getStreamFilterBuffer());
     }
 
-    public function testFailure()
+    public function testFailure(): void
     {
         TestPublisher::setResult(false);
 
diff --git a/tests/system/Commands/RoutesTest.php b/tests/system/Commands/RoutesTest.php
index bb89d35bb96d..d1625dcfc1bc 100644
--- a/tests/system/Commands/RoutesTest.php
+++ b/tests/system/Commands/RoutesTest.php
@@ -51,7 +51,7 @@ private function getCleanRoutes(): RouteCollection
         return $routes;
     }
 
-    public function testRoutesCommand()
+    public function testRoutesCommand(): void
     {
         $this->getCleanRoutes();
 
@@ -77,7 +77,7 @@ public function testRoutesCommand()
         $this->assertStringContainsString($expected, $this->getBuffer());
     }
 
-    public function testRoutesCommandSortByHandler()
+    public function testRoutesCommandSortByHandler(): void
     {
         $this->getCleanRoutes();
 
@@ -103,7 +103,7 @@ public function testRoutesCommandSortByHandler()
         $this->assertStringContainsString($expected, $this->getBuffer());
     }
 
-    public function testRoutesCommandAutoRouteImproved()
+    public function testRoutesCommandAutoRouteImproved(): void
     {
         $routes = $this->getCleanRoutes();
 
@@ -136,7 +136,7 @@ public function testRoutesCommandAutoRouteImproved()
         $this->assertStringContainsString($expected, $this->getBuffer());
     }
 
-    public function testRoutesCommandRouteLegacy()
+    public function testRoutesCommandRouteLegacy(): void
     {
         $routes = $this->getCleanRoutes();
 
diff --git a/tests/system/Commands/ScaffoldGeneratorTest.php b/tests/system/Commands/ScaffoldGeneratorTest.php
index 113710725143..4caa26fd123f 100644
--- a/tests/system/Commands/ScaffoldGeneratorTest.php
+++ b/tests/system/Commands/ScaffoldGeneratorTest.php
@@ -43,7 +43,7 @@ protected function getFileContents(string $filepath): string
         return file_get_contents($filepath) ?: '';
     }
 
-    public function testCreateComponentProducesManyFiles()
+    public function testCreateComponentProducesManyFiles(): void
     {
         command('make:scaffold people');
 
@@ -66,7 +66,7 @@ public function testCreateComponentProducesManyFiles()
         unlink(APPPATH . 'Database/Seeds/People.php');
     }
 
-    public function testCreateComponentWithManyOptions()
+    public function testCreateComponentWithManyOptions(): void
     {
         command('make:scaffold user -restful -return entity');
 
@@ -95,7 +95,7 @@ public function testCreateComponentWithManyOptions()
         unlink(APPPATH . 'Models/User.php');
     }
 
-    public function testCreateComponentWithOptionSuffix()
+    public function testCreateComponentWithOptionSuffix(): void
     {
         command('make:scaffold order -suffix');
 
@@ -118,7 +118,7 @@ public function testCreateComponentWithOptionSuffix()
         unlink(APPPATH . 'Models/OrderModel.php');
     }
 
-    public function testCreateComponentWithOptionForce()
+    public function testCreateComponentWithOptionForce(): void
     {
         command('make:controller fixer');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
@@ -151,7 +151,7 @@ public function testCreateComponentWithOptionForce()
         unlink(APPPATH . 'Models/Fixer.php');
     }
 
-    public function testCreateComponentWithOptionNamespace()
+    public function testCreateComponentWithOptionNamespace(): void
     {
         command('make:scaffold product -namespace App');
 
diff --git a/tests/system/Commands/SeederGeneratorTest.php b/tests/system/Commands/SeederGeneratorTest.php
index 57586084f402..035168759f52 100644
--- a/tests/system/Commands/SeederGeneratorTest.php
+++ b/tests/system/Commands/SeederGeneratorTest.php
@@ -34,14 +34,14 @@ protected function tearDown(): void
         }
     }
 
-    public function testGenerateSeeder()
+    public function testGenerateSeeder(): void
     {
         command('make:seeder cars');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
         $this->assertFileExists(APPPATH . 'Database/Seeds/Cars.php');
     }
 
-    public function testGenerateSeederWithOptionSuffix()
+    public function testGenerateSeederWithOptionSuffix(): void
     {
         command('make:seeder cars -suffix');
         $this->assertStringContainsString('File created: ', $this->getStreamFilterBuffer());
diff --git a/tests/system/Commands/Utilities/NamespacesTest.php b/tests/system/Commands/Utilities/NamespacesTest.php
index 26eabd32895f..755dd70f7cc6 100644
--- a/tests/system/Commands/Utilities/NamespacesTest.php
+++ b/tests/system/Commands/Utilities/NamespacesTest.php
@@ -47,7 +47,7 @@ protected function getBuffer()
         }, str_replace(PHP_EOL, "\n", $this->getStreamFilterBuffer()));
     }
 
-    public function testNamespacesCommandCodeIgniterOnly()
+    public function testNamespacesCommandCodeIgniterOnly(): void
     {
         command('namespaces -c');
 
@@ -65,7 +65,7 @@ public function testNamespacesCommandCodeIgniterOnly()
         $this->assertStringContainsString($expected, $this->getBuffer());
     }
 
-    public function testNamespacesCommandAllNamespaces()
+    public function testNamespacesCommandAllNamespaces(): void
     {
         command('namespaces');
 
diff --git a/tests/system/Commands/Utilities/Routes/AutoRouteCollectorTest.php b/tests/system/Commands/Utilities/Routes/AutoRouteCollectorTest.php
index 9279bd47b70c..2db5a603fb95 100644
--- a/tests/system/Commands/Utilities/Routes/AutoRouteCollectorTest.php
+++ b/tests/system/Commands/Utilities/Routes/AutoRouteCollectorTest.php
@@ -20,7 +20,7 @@
  */
 final class AutoRouteCollectorTest extends CIUnitTestCase
 {
-    public function testGet()
+    public function testGet(): void
     {
         $namespace = 'Tests\Support\Controllers';
         $collector = new AutoRouteCollector(
diff --git a/tests/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollectorTest.php b/tests/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollectorTest.php
index 4b99de7dbb07..d9dfee3e98ad 100644
--- a/tests/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollectorTest.php
+++ b/tests/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollectorTest.php
@@ -52,7 +52,7 @@ private function createAutoRouteCollector(array $filterConfigFilters): AutoRoute
         );
     }
 
-    public function testGetFilterMatches()
+    public function testGetFilterMatches(): void
     {
         $filterConfigFilters = ['honeypot' => ['before' => ['newautorouting/save*']]];
         $collector           = $this->createAutoRouteCollector($filterConfigFilters);
@@ -80,7 +80,7 @@ public function testGetFilterMatches()
         $this->assertSame($expected, $routes);
     }
 
-    public function testGetFilterDoesNotMatch()
+    public function testGetFilterDoesNotMatch(): void
     {
         $filterConfigFilters = ['honeypot' => ['before' => ['newautorouting/save/*/*']]];
         $collector           = $this->createAutoRouteCollector($filterConfigFilters);
diff --git a/tests/system/Commands/Utilities/Routes/AutoRouterImproved/ControllerMethodReaderTest.php b/tests/system/Commands/Utilities/Routes/AutoRouterImproved/ControllerMethodReaderTest.php
index 5df8c4f8ff0d..e3e23c29dc7a 100644
--- a/tests/system/Commands/Utilities/Routes/AutoRouterImproved/ControllerMethodReaderTest.php
+++ b/tests/system/Commands/Utilities/Routes/AutoRouterImproved/ControllerMethodReaderTest.php
@@ -34,7 +34,7 @@ private function createControllerMethodReader(
         return new ControllerMethodReader($namespace, $methods);
     }
 
-    public function testRead()
+    public function testRead(): void
     {
         $reader = $this->createControllerMethodReader();
 
@@ -64,7 +64,7 @@ public function testRead()
         $this->assertSame($expected, $routes);
     }
 
-    public function testReadDefaultController()
+    public function testReadDefaultController(): void
     {
         $reader = $this->createControllerMethodReader(
             'CodeIgniter\Commands\Utilities\Routes\AutoRouterImproved\Controllers'
@@ -99,7 +99,7 @@ public function testReadDefaultController()
         $this->assertSame($expected, $routes);
     }
 
-    public function testReadControllerWithRemap()
+    public function testReadControllerWithRemap(): void
     {
         $reader = $this->createControllerMethodReader();
 
diff --git a/tests/system/Commands/Utilities/Routes/AutoRouterImproved/Controllers/Home.php b/tests/system/Commands/Utilities/Routes/AutoRouterImproved/Controllers/Home.php
index 4666a709a07b..f4836ffc7f6a 100644
--- a/tests/system/Commands/Utilities/Routes/AutoRouterImproved/Controllers/Home.php
+++ b/tests/system/Commands/Utilities/Routes/AutoRouterImproved/Controllers/Home.php
@@ -18,18 +18,18 @@
  */
 class Home extends Controller
 {
-    public function getIndex()
+    public function getIndex(): void
     {
     }
 
-    public function postIndex()
+    public function postIndex(): void
     {
     }
 
     /**
      * This method cannot be accessible.
      */
-    public function getFoo()
+    public function getFoo(): void
     {
     }
 }
diff --git a/tests/system/Commands/Utilities/Routes/ControllerFinderTest.php b/tests/system/Commands/Utilities/Routes/ControllerFinderTest.php
index 32a2bd54ab1c..fecc080d8705 100644
--- a/tests/system/Commands/Utilities/Routes/ControllerFinderTest.php
+++ b/tests/system/Commands/Utilities/Routes/ControllerFinderTest.php
@@ -21,7 +21,7 @@
  */
 final class ControllerFinderTest extends CIUnitTestCase
 {
-    public function testFind()
+    public function testFind(): void
     {
         $namespace = 'Tests\Support\Controllers';
         $finder    = new ControllerFinder($namespace);
diff --git a/tests/system/Commands/Utilities/Routes/ControllerMethodReaderTest.php b/tests/system/Commands/Utilities/Routes/ControllerMethodReaderTest.php
index ee315135304d..349d814b23c7 100644
--- a/tests/system/Commands/Utilities/Routes/ControllerMethodReaderTest.php
+++ b/tests/system/Commands/Utilities/Routes/ControllerMethodReaderTest.php
@@ -22,7 +22,7 @@
  */
 final class ControllerMethodReaderTest extends CIUnitTestCase
 {
-    public function testRead()
+    public function testRead(): void
     {
         $namespace = 'Tests\Support\Controllers';
         $reader    = new ControllerMethodReader($namespace);
@@ -90,7 +90,7 @@ public function testRead()
         $this->assertSame($expected, $routes);
     }
 
-    public function testReadControllerWithRemap()
+    public function testReadControllerWithRemap(): void
     {
         $namespace = 'Tests\Support\Controllers';
         $reader    = new ControllerMethodReader($namespace);
diff --git a/tests/system/Commands/Utilities/Routes/FilterCollectorTest.php b/tests/system/Commands/Utilities/Routes/FilterCollectorTest.php
index ff4df4090c4c..1363d468a49d 100644
--- a/tests/system/Commands/Utilities/Routes/FilterCollectorTest.php
+++ b/tests/system/Commands/Utilities/Routes/FilterCollectorTest.php
@@ -21,7 +21,7 @@
  */
 final class FilterCollectorTest extends CIUnitTestCase
 {
-    public function testGet()
+    public function testGet(): void
     {
         $routes = Services::routes();
         $routes->resetRoutes();
diff --git a/tests/system/Commands/Utilities/Routes/FilterFinderTest.php b/tests/system/Commands/Utilities/Routes/FilterFinderTest.php
index ace71d9d7e2d..15b970cd4351 100644
--- a/tests/system/Commands/Utilities/Routes/FilterFinderTest.php
+++ b/tests/system/Commands/Utilities/Routes/FilterFinderTest.php
@@ -96,7 +96,7 @@ private function createFilters(array $config = []): Filters
         return new Filters($filtersConfig, $this->request, $this->response, $this->moduleConfig);
     }
 
-    public function testFindGlobalsFilters()
+    public function testFindGlobalsFilters(): void
     {
         $collection = $this->createRouteCollection();
         $router     = $this->createRouter($collection);
@@ -113,7 +113,7 @@ public function testFindGlobalsFilters()
         $this->assertSame($expected, $filters);
     }
 
-    public function testFindGlobalsFiltersWithRedirectRoute()
+    public function testFindGlobalsFiltersWithRedirectRoute(): void
     {
         $collection = $this->createRouteCollection();
         $collection->addRedirect('users/about', 'profile');
@@ -132,7 +132,7 @@ public function testFindGlobalsFiltersWithRedirectRoute()
         $this->assertSame($expected, $filters);
     }
 
-    public function testFindGlobalsAndRouteFilters()
+    public function testFindGlobalsAndRouteFilters(): void
     {
         $collection = $this->createRouteCollection();
         $collection->get('admin', ' AdminController::index', ['filter' => 'honeypot']);
@@ -150,7 +150,7 @@ public function testFindGlobalsAndRouteFilters()
         $this->assertSame($expected, $filters);
     }
 
-    public function testFindGlobalsAndRouteClassnameFilters()
+    public function testFindGlobalsAndRouteClassnameFilters(): void
     {
         $collection = $this->createRouteCollection();
         $collection->get('admin', ' AdminController::index', ['filter' => InvalidChars::class]);
@@ -168,7 +168,7 @@ public function testFindGlobalsAndRouteClassnameFilters()
         $this->assertSame($expected, $filters);
     }
 
-    public function testFindGlobalsAndRouteMultipleFilters()
+    public function testFindGlobalsAndRouteMultipleFilters(): void
     {
         config('Feature')->multipleFilters = true;
 
diff --git a/tests/system/Commands/Utilities/Routes/SampleURIGeneratorTest.php b/tests/system/Commands/Utilities/Routes/SampleURIGeneratorTest.php
index fe7bf12613a7..ec4acc47259e 100644
--- a/tests/system/Commands/Utilities/Routes/SampleURIGeneratorTest.php
+++ b/tests/system/Commands/Utilities/Routes/SampleURIGeneratorTest.php
@@ -24,7 +24,7 @@ final class SampleURIGeneratorTest extends CIUnitTestCase
     /**
      * @dataProvider routeKeyProvider
      */
-    public function testGet(string $routeKey, string $expected)
+    public function testGet(string $routeKey, string $expected): void
     {
         $generator = new SampleURIGenerator();
 
@@ -44,7 +44,7 @@ public function routeKeyProvider(): iterable
         ];
     }
 
-    public function testGetFromPlaceholderCustomPlaceholder()
+    public function testGetFromPlaceholderCustomPlaceholder(): void
     {
         $routes = Services::routes();
         $routes->addPlaceholder(
diff --git a/tests/system/Commands/ValidationGeneratorTest.php b/tests/system/Commands/ValidationGeneratorTest.php
index 39c3fd833a5f..ec208179be79 100644
--- a/tests/system/Commands/ValidationGeneratorTest.php
+++ b/tests/system/Commands/ValidationGeneratorTest.php
@@ -38,13 +38,13 @@ protected function tearDown(): void
         }
     }
 
-    public function testGenerateValidation()
+    public function testGenerateValidation(): void
     {
         command('make:validation user');
         $this->assertFileExists(APPPATH . 'Validation/User.php');
     }
 
-    public function testGenerateValidationWithOptionSuffix()
+    public function testGenerateValidationWithOptionSuffix(): void
     {
         command('make:validation admin -suffix');
         $this->assertFileExists(APPPATH . 'Validation/AdminValidation.php');
diff --git a/tests/system/CommonFunctionsSendTest.php b/tests/system/CommonFunctionsSendTest.php
index 365049315778..a580366277fb 100644
--- a/tests/system/CommonFunctionsSendTest.php
+++ b/tests/system/CommonFunctionsSendTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testRedirectResponseCookiesSent()
+    public function testRedirectResponseCookiesSent(): void
     {
         $loginTime = time();
 
diff --git a/tests/system/CommonFunctionsTest.php b/tests/system/CommonFunctionsTest.php
index b304eeab69eb..8d4f7199d0e1 100644
--- a/tests/system/CommonFunctionsTest.php
+++ b/tests/system/CommonFunctionsTest.php
@@ -56,7 +56,7 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    public function testStringifyAttributes()
+    public function testStringifyAttributes(): void
     {
         $this->assertSame(' class="foo" id="bar"', stringify_attributes(['class' => 'foo', 'id' => 'bar']));
 
@@ -73,7 +73,7 @@ public function testStringifyAttributes()
         $this->assertSame('', stringify_attributes([]));
     }
 
-    public function testStringifyJsAttributes()
+    public function testStringifyJsAttributes(): void
     {
         $this->assertSame('width=800,height=600', stringify_attributes(['width' => '800', 'height' => '600'], true));
 
@@ -83,26 +83,26 @@ public function testStringifyJsAttributes()
         $this->assertSame('width=800,height=600', stringify_attributes($atts, true));
     }
 
-    public function testEnvReturnsDefault()
+    public function testEnvReturnsDefault(): void
     {
         $this->assertSame('baz', env('foo', 'baz'));
     }
 
-    public function testEnvGetsFromSERVER()
+    public function testEnvGetsFromSERVER(): void
     {
         $_SERVER['foo'] = 'bar';
 
         $this->assertSame('bar', env('foo', 'baz'));
     }
 
-    public function testEnvGetsFromENV()
+    public function testEnvGetsFromENV(): void
     {
         $_ENV['foo'] = 'bar';
 
         $this->assertSame('bar', env('foo', 'baz'));
     }
 
-    public function testEnvBooleans()
+    public function testEnvBooleans(): void
     {
         $_ENV['p1'] = 'true';
         $_ENV['p2'] = 'false';
@@ -115,7 +115,7 @@ public function testEnvBooleans()
         $this->assertNull(env('p4'));
     }
 
-    public function testRedirectReturnsRedirectResponse()
+    public function testRedirectReturnsRedirectResponse(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -133,12 +133,12 @@ public function testRedirectReturnsRedirectResponse()
         $this->assertInstanceOf(RedirectResponse::class, redirect('base'));
     }
 
-    public function testRedirectDefault()
+    public function testRedirectDefault(): void
     {
         $this->assertInstanceOf(RedirectResponse::class, redirect());
     }
 
-    public function testRequestIncomingRequest()
+    public function testRequestIncomingRequest(): void
     {
         Services::createRequest(new App());
 
@@ -147,7 +147,7 @@ public function testRequestIncomingRequest()
         $this->assertInstanceOf(IncomingRequest::class, $request);
     }
 
-    public function testRequestCLIRequest()
+    public function testRequestCLIRequest(): void
     {
         Services::createRequest(new App(), true);
 
@@ -156,19 +156,19 @@ public function testRequestCLIRequest()
         $this->assertInstanceOf(CLIRequest::class, $request);
     }
 
-    public function testResponse()
+    public function testResponse(): void
     {
         $response = response();
 
         $this->assertInstanceOf(Response::class, $response);
     }
 
-    public function testSolidusElement()
+    public function testSolidusElement(): void
     {
         $this->assertSame('', _solidus());
     }
 
-    public function testSolidusElementXHTML()
+    public function testSolidusElementXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -180,7 +180,7 @@ public function testSolidusElementXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testView()
+    public function testView(): void
     {
         $data = [
             'testString' => 'bar',
@@ -190,7 +190,7 @@ public function testView()
         $this->assertStringContainsString($expected, view('\Tests\Support\View\Views\simple', $data));
     }
 
-    public function testViewSavedData()
+    public function testViewSavedData(): void
     {
         $data = [
             'testString' => 'bar',
@@ -201,26 +201,26 @@ public function testViewSavedData()
         $this->assertStringContainsString($expected, view('\Tests\Support\View\Views\simple'));
     }
 
-    public function testViewCell()
+    public function testViewCell(): void
     {
         $expected = 'Hello';
         $this->assertSame($expected, view_cell('\Tests\Support\View\SampleClass::hello'));
     }
 
-    public function testEscapeWithDifferentEncodings()
+    public function testEscapeWithDifferentEncodings(): void
     {
         $this->assertSame('&lt;x', esc('<x', 'html', 'utf-8'));
         $this->assertSame('&lt;x', esc('<x', 'html', 'iso-8859-1'));
         $this->assertSame('&lt;x', esc('<x', 'html', 'windows-1251'));
     }
 
-    public function testEscapeBadContext()
+    public function testEscapeBadContext(): void
     {
         $this->expectException('InvalidArgumentException');
         esc(['width' => '800', 'height' => '600'], 'bogus');
     }
 
-    public function testEscapeBadContextZero()
+    public function testEscapeBadContextZero(): void
     {
         $this->expectException('InvalidArgumentException');
         esc('<script>', '0');
@@ -230,7 +230,7 @@ public function testEscapeBadContextZero()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSessionInstance()
+    public function testSessionInstance(): void
     {
         $this->injectSessionMock();
 
@@ -241,7 +241,7 @@ public function testSessionInstance()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSessionVariable()
+    public function testSessionVariable(): void
     {
         $this->injectSessionMock();
 
@@ -254,7 +254,7 @@ public function testSessionVariable()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSessionVariableNotThere()
+    public function testSessionVariableNotThere(): void
     {
         $this->injectSessionMock();
 
@@ -262,7 +262,7 @@ public function testSessionVariableNotThere()
         $this->assertNull(session('notbogus'));
     }
 
-    public function testRouteTo()
+    public function testRouteTo(): void
     {
         // prime the pump
         $routes = service('routes');
@@ -273,7 +273,7 @@ public function testRouteTo()
         $this->assertSame('/path/string/to/13', route_to('myController::goto', 'string', 13));
     }
 
-    public function testRouteToInCliWithoutLocaleInRoute()
+    public function testRouteToInCliWithoutLocaleInRoute(): void
     {
         Services::createRequest(new App(), true);
         $routes = service('routes');
@@ -284,7 +284,7 @@ public function testRouteToInCliWithoutLocaleInRoute()
         $this->assertSame('/path/string/to/13', route_to('myController::goto', 'string', 13));
     }
 
-    public function testRouteToInCliWithLocaleInRoute()
+    public function testRouteToInCliWithLocaleInRoute(): void
     {
         Services::createRequest(new App(), true);
         $routes = service('routes');
@@ -298,7 +298,7 @@ public function testRouteToInCliWithLocaleInRoute()
         );
     }
 
-    public function testRouteToWithUnsupportedLocale()
+    public function testRouteToWithUnsupportedLocale(): void
     {
         Services::createRequest(new App(), false);
         $routes = service('routes');
@@ -312,64 +312,64 @@ public function testRouteToWithUnsupportedLocale()
         );
     }
 
-    public function testInvisible()
+    public function testInvisible(): void
     {
         $this->assertSame('Javascript', remove_invisible_characters("Java\0script"));
     }
 
-    public function testInvisibleEncoded()
+    public function testInvisibleEncoded(): void
     {
         $this->assertSame('Javascript', remove_invisible_characters('Java%0cscript'));
     }
 
-    public function testAppTimezone()
+    public function testAppTimezone(): void
     {
         $this->assertSame('UTC', app_timezone());
     }
 
-    public function testCSRFToken()
+    public function testCSRFToken(): void
     {
         Services::injectMock('security', new MockSecurity(new App()));
 
         $this->assertSame('csrf_test_name', csrf_token());
     }
 
-    public function testCSRFHeader()
+    public function testCSRFHeader(): void
     {
         $this->assertSame('X-CSRF-TOKEN', csrf_header());
     }
 
-    public function testHash()
+    public function testHash(): void
     {
         $this->assertSame(32, strlen(csrf_hash()));
     }
 
-    public function testCSRFField()
+    public function testCSRFField(): void
     {
         $this->assertStringContainsString('<input type="hidden" ', csrf_field());
     }
 
-    public function testCSRFMeta()
+    public function testCSRFMeta(): void
     {
         $this->assertStringContainsString('<meta name="X-CSRF-TOKEN" ', csrf_meta());
     }
 
-    public function testModelNotExists()
+    public function testModelNotExists(): void
     {
         $this->assertNull(model(UnexsistenceClass::class));
     }
 
-    public function testModelExistsBasename()
+    public function testModelExistsBasename(): void
     {
         $this->assertInstanceOf(JobModel::class, model('JobModel'));
     }
 
-    public function testModelExistsClassname()
+    public function testModelExistsClassname(): void
     {
         $this->assertInstanceOf(JobModel::class, model(JobModel::class));
     }
 
-    public function testModelExistsAbsoluteClassname()
+    public function testModelExistsAbsoluteClassname(): void
     {
         $this->assertInstanceOf(JobModel::class, model(JobModel::class));
     }
@@ -378,7 +378,7 @@ public function testModelExistsAbsoluteClassname()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testOldInput()
+    public function testOldInput(): void
     {
         $this->injectSessionMock();
         // setup from RedirectResponseTest...
@@ -413,7 +413,7 @@ public function testOldInput()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testOldInputSerializeData()
+    public function testOldInputSerializeData(): void
     {
         $this->injectSessionMock();
         // setup from RedirectResponseTest...
@@ -448,7 +448,7 @@ public function testOldInputSerializeData()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testOldInputArray()
+    public function testOldInputArray(): void
     {
         $this->injectSessionMock();
         // setup from RedirectResponseTest...
@@ -480,13 +480,13 @@ public function testOldInputArray()
         $this->assertSame($locations, old('location'));
     }
 
-    public function testReallyWritable()
+    public function testReallyWritable(): void
     {
         // cannot test fully on *nix
         $this->assertTrue(is_really_writable(WRITEPATH));
     }
 
-    public function testSlashItem()
+    public function testSlashItem(): void
     {
         $this->assertSame('/', slash_item('cookiePath')); // /
         $this->assertSame('', slash_item('cookieDomain')); // ''
@@ -496,7 +496,7 @@ public function testSlashItem()
         $this->assertSame('1/', slash_item('cookieHTTPOnly')); // true
     }
 
-    public function testSlashItemOnInexistentItem()
+    public function testSlashItemOnInexistentItem(): void
     {
         $this->assertNull(slash_item('foo'));
         $this->assertNull(slash_item('bar'));
@@ -504,7 +504,7 @@ public function testSlashItemOnInexistentItem()
         $this->assertNull(slash_item('indices'));
     }
 
-    public function testSlashItemThrowsErrorOnNonStringableItem()
+    public function testSlashItemThrowsErrorOnNonStringableItem(): void
     {
         $this->expectException(RuntimeException::class);
         $this->expectExceptionMessage('Cannot convert "Config\\App::$supportedLocales" of type "array" to type "string".');
@@ -512,7 +512,7 @@ public function testSlashItemThrowsErrorOnNonStringableItem()
         slash_item('supportedLocales');
     }
 
-    protected function injectSessionMock()
+    protected function injectSessionMock(): void
     {
         $defaults = [
             'sessionDriver'            => FileHandler::class,
@@ -542,7 +542,7 @@ protected function injectSessionMock()
 
     // Make sure cookies are set by RedirectResponse this way
     // See https://github.com/codeigniter4/CodeIgniter4/issues/1393
-    public function testRedirectResponseCookies1()
+    public function testRedirectResponseCookies1(): void
     {
         $loginTime = time();
 
@@ -561,7 +561,7 @@ public function testRedirectResponseCookies1()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testTrace()
+    public function testTrace(): void
     {
         ob_start();
         trace();
@@ -570,7 +570,7 @@ public function testTrace()
         $this->assertStringContainsString('Debug Backtrace', $content);
     }
 
-    public function testViewNotSaveData()
+    public function testViewNotSaveData(): void
     {
         $data = [
             'testString' => 'bar',
@@ -584,7 +584,7 @@ public function testViewNotSaveData()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testForceHttpsNullRequestAndResponse()
+    public function testForceHttpsNullRequestAndResponse(): void
     {
         $this->assertNull(Services::response()->header('Location'));
 
@@ -599,7 +599,7 @@ public function testForceHttpsNullRequestAndResponse()
      * @param mixed $input
      * @param mixed $expected
      */
-    public function testCleanPathActuallyCleaningThePaths($input, $expected)
+    public function testCleanPathActuallyCleaningThePaths($input, $expected): void
     {
         $this->assertSame($expected, clean_path($input));
     }
@@ -632,13 +632,13 @@ public function dirtyPathsProvider(): iterable
         ];
     }
 
-    public function testIsCli()
+    public function testIsCli(): void
     {
         $this->assertIsBool(is_cli());
         $this->assertTrue(is_cli());
     }
 
-    public function testDWithCSP()
+    public function testDWithCSP(): void
     {
         $this->resetServices();
 
@@ -664,7 +664,7 @@ public function testDWithCSP()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testTraceWithCSP()
+    public function testTraceWithCSP(): void
     {
         $this->resetServices();
 
@@ -682,7 +682,7 @@ public function testTraceWithCSP()
         trace();
     }
 
-    public function testCspStyleNonce()
+    public function testCspStyleNonce(): void
     {
         $config             = config('App');
         $config->CSPEnabled = true;
@@ -690,7 +690,7 @@ public function testCspStyleNonce()
         $this->assertStringStartsWith('nonce="', csp_style_nonce());
     }
 
-    public function testCspScriptNonce()
+    public function testCspScriptNonce(): void
     {
         $config             = config('App');
         $config->CSPEnabled = true;
@@ -698,7 +698,7 @@ public function testCspScriptNonce()
         $this->assertStringStartsWith('nonce="', csp_script_nonce());
     }
 
-    public function testLangOnCLI()
+    public function testLangOnCLI(): void
     {
         Services::createRequest(new App(), true);
 
@@ -709,13 +709,13 @@ public function testLangOnCLI()
         $this->resetServices();
     }
 
-    public function testIsWindows()
+    public function testIsWindows(): void
     {
         $this->assertSame(strpos(php_uname(), 'Windows') !== false, is_windows());
         $this->assertSame(defined('PHP_WINDOWS_VERSION_MAJOR'), is_windows());
     }
 
-    public function testIsWindowsUsingMock()
+    public function testIsWindowsUsingMock(): void
     {
         is_windows(true);
         $this->assertTrue(is_windows());
diff --git a/tests/system/CommonHelperTest.php b/tests/system/CommonHelperTest.php
index e39ee9504594..46603dee30ad 100644
--- a/tests/system/CommonHelperTest.php
+++ b/tests/system/CommonHelperTest.php
@@ -85,7 +85,7 @@ private function getMockLocator()
             ->getMock();
     }
 
-    public function testHelperWithFatalLocatorThrowsException()
+    public function testHelperWithFatalLocatorThrowsException(): void
     {
         // Replace the locator with one that will fail if it is called
         $locator = new FatalLocator(Services::autoloader());
@@ -101,7 +101,7 @@ public function testHelperWithFatalLocatorThrowsException()
         $this->assertTrue($exception);
     }
 
-    public function testHelperLoadsOnce()
+    public function testHelperLoadsOnce(): void
     {
         // Load it the first time
         helper('baguette');
diff --git a/tests/system/Config/BaseConfigTest.php b/tests/system/Config/BaseConfigTest.php
index 3d1fe88c53a8..2da390392ed6 100644
--- a/tests/system/Config/BaseConfigTest.php
+++ b/tests/system/Config/BaseConfigTest.php
@@ -47,7 +47,7 @@ protected function setUp(): void
         }
     }
 
-    public function testBasicValues()
+    public function testBasicValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -59,7 +59,7 @@ public function testBasicValues()
         $this->assertSame(18, $config->golf);
     }
 
-    public function testUseDefaultValueTypeIntAndFloatValues()
+    public function testUseDefaultValueTypeIntAndFloatValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -69,7 +69,7 @@ public function testUseDefaultValueTypeIntAndFloatValues()
         $this->assertSame(999, $config->int);
     }
 
-    public function testUseDefaultValueTypeStringValue()
+    public function testUseDefaultValueTypeStringValue(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -82,7 +82,7 @@ public function testUseDefaultValueTypeStringValue()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testServerValues()
+    public function testServerValues(): void
     {
         $_SERVER = [
             'simpleconfig.shortie' => 123,
@@ -96,7 +96,7 @@ public function testServerValues()
         $this->assertSame('456', $config->longie);
     }
 
-    public function testEnvironmentOverrides()
+    public function testEnvironmentOverrides(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -126,7 +126,7 @@ public function testEnvironmentOverrides()
         $this->assertSame(20, $config->size);
     }
 
-    public function testPrefixedValues()
+    public function testPrefixedValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -136,7 +136,7 @@ public function testPrefixedValues()
         $this->assertSame('baz', $config->onedeep);
     }
 
-    public function testPrefixedArrayValues()
+    public function testPrefixedArrayValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -151,7 +151,7 @@ public function testPrefixedArrayValues()
         $this->assertFalse($config->crew['doctor']);
     }
 
-    public function testArrayValues()
+    public function testArrayValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -163,7 +163,7 @@ public function testArrayValues()
         $this->assertSame('bar', $config->second);
     }
 
-    public function testSetsDefaultValues()
+    public function testSetsDefaultValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'commented.env');
         $dotenv->load();
@@ -178,7 +178,7 @@ public function testSetsDefaultValues()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSetsDefaultValuesEncryptionUsingHex2Bin()
+    public function testSetsDefaultValuesEncryptionUsingHex2Bin(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'encryption.env');
         $dotenv->load();
@@ -193,7 +193,7 @@ public function testSetsDefaultValuesEncryptionUsingHex2Bin()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSetDefaultValuesEncryptionUsingBase64()
+    public function testSetDefaultValuesEncryptionUsingBase64(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'base64encryption.env');
         $dotenv->load();
@@ -203,7 +203,7 @@ public function testSetDefaultValuesEncryptionUsingBase64()
         $this->assertSame('OpenSSL', $config->driver);
     }
 
-    public function testSetsDefaultValuesHex2Bin()
+    public function testSetsDefaultValuesHex2Bin(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'commented.env');
         $dotenv->load();
@@ -214,7 +214,7 @@ public function testSetsDefaultValuesHex2Bin()
         $this->assertSame('MCrypt', $config->driver);
     }
 
-    public function testSetDefaultValuesBase64()
+    public function testSetDefaultValuesBase64(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'commented.env');
         $dotenv->load();
@@ -224,7 +224,7 @@ public function testSetDefaultValuesBase64()
         $this->assertSame('MCrypt', $config->driver);
     }
 
-    public function testRecognizesLooseValues()
+    public function testRecognizesLooseValues(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'loose.env');
         $dotenv->load();
@@ -237,7 +237,7 @@ public function testRecognizesLooseValues()
         $this->assertFalse($config->QFALSE);
     }
 
-    public function testRegistrars()
+    public function testRegistrars(): void
     {
         $config              = new RegistrarConfig();
         $config::$registrars = [TestRegistrar::class];
@@ -251,7 +251,7 @@ public function testRegistrars()
         $this->assertSame(['baz', 'first', 'second'], $config->bar);
     }
 
-    public function testBadRegistrar()
+    public function testBadRegistrar(): void
     {
         // Shouldn't change any values.
         $config              = new RegistrarConfig();
@@ -265,7 +265,7 @@ public function testBadRegistrar()
         $this->assertSame('bar', $config->foo);
     }
 
-    public function testNotEnabled()
+    public function testNotEnabled(): void
     {
         $modulesConfig          = config('Modules');
         $modulesConfig->enabled = false;
@@ -280,7 +280,7 @@ public function testNotEnabled()
         $this->assertSame($expected, $config::$registrars);
     }
 
-    public function testDidDiscovery()
+    public function testDidDiscovery(): void
     {
         $modulesConfig          = config('Modules');
         $modulesConfig->enabled = true;
diff --git a/tests/system/Config/ConfigTest.php b/tests/system/Config/ConfigTest.php
index 52951d7ef87c..6bd4103a7aa2 100644
--- a/tests/system/Config/ConfigTest.php
+++ b/tests/system/Config/ConfigTest.php
@@ -22,7 +22,7 @@
  */
 final class ConfigTest extends CIUnitTestCase
 {
-    public function testCreateSingleInstance()
+    public function testCreateSingleInstance(): void
     {
         $Config          = Config::get('DocTypes', false);
         $NamespaceConfig = Config::get(DocTypes::class, false);
@@ -31,14 +31,14 @@ public function testCreateSingleInstance()
         $this->assertInstanceOf(DocTypes::class, $NamespaceConfig);
     }
 
-    public function testCreateInvalidInstance()
+    public function testCreateInvalidInstance(): void
     {
         $Config = Config::get('gfnusvjai', false);
 
         $this->assertNull($Config);
     }
 
-    public function testCreateSharedInstance()
+    public function testCreateSharedInstance(): void
     {
         $Config  = Config::get('DocTypes');
         $Config2 = Config::get(DocTypes::class);
@@ -46,7 +46,7 @@ public function testCreateSharedInstance()
         $this->assertSame($Config2, $Config);
     }
 
-    public function testCreateNonConfig()
+    public function testCreateNonConfig(): void
     {
         $Config = Config::get('Constants', false);
 
@@ -57,7 +57,7 @@ public function testCreateNonConfig()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testInjection()
+    public function testInjection(): void
     {
         Config::reset();
         Config::injectMock('Banana', new stdClass());
diff --git a/tests/system/Config/DotEnvTest.php b/tests/system/Config/DotEnvTest.php
index f47376ef3786..6bd8b23958f5 100644
--- a/tests/system/Config/DotEnvTest.php
+++ b/tests/system/Config/DotEnvTest.php
@@ -49,7 +49,7 @@ protected function tearDown(): void
         $this->root = null;
     }
 
-    public function testReturnsFalseIfCannotFindFile()
+    public function testReturnsFalseIfCannotFindFile(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'bogus');
         $this->assertFalse($dotenv->load());
@@ -58,7 +58,7 @@ public function testReturnsFalseIfCannotFindFile()
     /**
      * @dataProvider provideLoadVars
      */
-    public function testLoadsVars(string $expected, string $varname)
+    public function testLoadsVars(string $expected, string $varname): void
     {
         $dotenv = new DotEnv($this->fixturesFolder);
         $dotenv->load();
@@ -85,7 +85,7 @@ public function provideLoadVars(): iterable
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testLoadsHex2Bin()
+    public function testLoadsHex2Bin(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'encryption.env');
         $dotenv->load();
@@ -99,7 +99,7 @@ public function testLoadsHex2Bin()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testLoadsBase64()
+    public function testLoadsBase64(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'base64encryption.env');
         $dotenv->load();
@@ -108,7 +108,7 @@ public function testLoadsBase64()
         $this->assertSame('OpenSSL', getenv('encryption.driver'));
     }
 
-    public function testLoadsNoneStringFiles()
+    public function testLoadsNoneStringFiles(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 2);
         $dotenv->load();
@@ -118,7 +118,7 @@ public function testLoadsNoneStringFiles()
         $this->assertSame('', getenv('NULL'));
     }
 
-    public function testCommentedLoadsVars()
+    public function testCommentedLoadsVars(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'commented.env');
         $dotenv->load();
@@ -131,7 +131,7 @@ public function testCommentedLoadsVars()
         $this->assertSame('', getenv('CNULL'));
     }
 
-    public function testLoadsUnreadableFile()
+    public function testLoadsUnreadableFile(): void
     {
         $file = 'unreadable.env';
         $path = rtrim($this->fixturesFolder, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR . $file;
@@ -142,7 +142,7 @@ public function testLoadsUnreadableFile()
         $dotenv->load();
     }
 
-    public function testQuotedDotenvLoadsEnvironmentVars()
+    public function testQuotedDotenvLoadsEnvironmentVars(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'quoted.env');
         $dotenv->load();
@@ -154,7 +154,7 @@ public function testQuotedDotenvLoadsEnvironmentVars()
         $this->assertSame('test some escaped characters like a quote (") or maybe a backslash (\\)', getenv('QESCAPED'));
     }
 
-    public function testSpacedValuesWithoutQuotesThrowsException()
+    public function testSpacedValuesWithoutQuotesThrowsException(): void
     {
         $this->expectException('InvalidArgumentException');
         $this->expectExceptionMessage('.env values containing spaces must be surrounded by quotes.');
@@ -163,7 +163,7 @@ public function testSpacedValuesWithoutQuotesThrowsException()
         $dotenv->load();
     }
 
-    public function testLoadsServerGlobals()
+    public function testLoadsServerGlobals(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -174,7 +174,7 @@ public function testLoadsServerGlobals()
         $this->assertSame('', $_SERVER['NULL']);
     }
 
-    public function testNamespacedVariables()
+    public function testNamespacedVariables(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, '.env');
         $dotenv->load();
@@ -182,7 +182,7 @@ public function testNamespacedVariables()
         $this->assertSame('complex', $_SERVER['SimpleConfig_simple_name']);
     }
 
-    public function testLoadsGetServerVar()
+    public function testLoadsGetServerVar(): void
     {
         $_SERVER['SER_VAR'] = 'TT';
         $dotenv             = new DotEnv($this->fixturesFolder, 'nested.env');
@@ -191,7 +191,7 @@ public function testLoadsGetServerVar()
         $this->assertSame('TT', $_ENV['NVAR7']);
     }
 
-    public function testLoadsEnvGlobals()
+    public function testLoadsEnvGlobals(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder);
         $dotenv->load();
@@ -201,7 +201,7 @@ public function testLoadsEnvGlobals()
         $this->assertSame('', $_ENV['NULL']);
     }
 
-    public function testNestedEnvironmentVars()
+    public function testNestedEnvironmentVars(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'nested.env');
         $dotenv->load();
@@ -211,7 +211,7 @@ public function testNestedEnvironmentVars()
         $this->assertSame('Hello/World!', $_ENV['NVAR8']);
     }
 
-    public function testDotenvAllowsSpecialCharacters()
+    public function testDotenvAllowsSpecialCharacters(): void
     {
         $dotenv = new DotEnv($this->fixturesFolder, 'specialchars.env');
         $dotenv->load();
diff --git a/tests/system/Config/FactoriesTest.php b/tests/system/Config/FactoriesTest.php
index 655329ad95de..c3b12c47d0ab 100644
--- a/tests/system/Config/FactoriesTest.php
+++ b/tests/system/Config/FactoriesTest.php
@@ -49,14 +49,14 @@ protected function getFactoriesStaticProperty(...$params)
         return $property;
     }
 
-    public function testGetsOptions()
+    public function testGetsOptions(): void
     {
         $result = Factories::getOptions('models');
 
         $this->assertTrue($result['preferApp']);
     }
 
-    public function testGetsDefaultOptions()
+    public function testGetsDefaultOptions(): void
     {
         $result = Factories::getOptions('blahblahs');
 
@@ -64,7 +64,7 @@ public function testGetsDefaultOptions()
         $this->assertSame('Blahblahs', $result['path']);
     }
 
-    public function testSetsOptions()
+    public function testSetsOptions(): void
     {
         Factories::setOptions('widgets', ['foo' => 'bar']);
 
@@ -74,7 +74,7 @@ public function testSetsOptions()
         $this->assertTrue($result['preferApp']);
     }
 
-    public function testUsesConfigOptions()
+    public function testUsesConfigOptions(): void
     {
         // Simulate having a $widgets property in App\Config\Factory
         $config = new class () extends Factory {
@@ -87,7 +87,7 @@ public function testUsesConfigOptions()
         $this->assertSame('bam', $result['bar']);
     }
 
-    public function testSetOptionsResets()
+    public function testSetOptionsResets(): void
     {
         Factories::injectMock('widgets', 'Banana', new stdClass());
 
@@ -102,7 +102,7 @@ public function testSetOptionsResets()
         $this->assertArrayNotHasKey('widgets', $result);
     }
 
-    public function testResetsAll()
+    public function testResetsAll(): void
     {
         Factories::setOptions('widgets', ['foo' => 'bar']);
 
@@ -112,7 +112,7 @@ public function testResetsAll()
         $this->assertSame([], $result);
     }
 
-    public function testResetsComponentOnly()
+    public function testResetsComponentOnly(): void
     {
         Factories::setOptions('widgets', ['foo' => 'bar']);
         Factories::setOptions('spigots', ['bar' => 'bam']);
@@ -124,62 +124,62 @@ public function testResetsComponentOnly()
         $this->assertArrayHasKey('widgets', $result);
     }
 
-    public function testGetsBasenameByBasename()
+    public function testGetsBasenameByBasename(): void
     {
         $this->assertSame('SomeWidget', Factories::getBasename('SomeWidget'));
     }
 
-    public function testGetsBasenameByClassname()
+    public function testGetsBasenameByClassname(): void
     {
         $this->assertSame('SomeWidget', Factories::getBasename(SomeWidget::class));
     }
 
-    public function testGetsBasenameByAbsoluteClassname()
+    public function testGetsBasenameByAbsoluteClassname(): void
     {
         $this->assertSame('UserModel', Factories::getBasename(UserModel::class));
     }
 
-    public function testGetsBasenameInvalid()
+    public function testGetsBasenameInvalid(): void
     {
         $this->assertSame('', Factories::getBasename('Tests\\Support\\'));
     }
 
-    public function testCreatesByBasename()
+    public function testCreatesByBasename(): void
     {
         $result = Factories::widgets('SomeWidget', ['getShared' => false]);
 
         $this->assertInstanceOf(SomeWidget::class, $result);
     }
 
-    public function testCreatesByClassname()
+    public function testCreatesByClassname(): void
     {
         $result = Factories::widgets(SomeWidget::class, ['getShared' => false]);
 
         $this->assertInstanceOf(SomeWidget::class, $result);
     }
 
-    public function testCreatesByAbsoluteClassname()
+    public function testCreatesByAbsoluteClassname(): void
     {
         $result = Factories::models(UserModel::class, ['getShared' => false]);
 
         $this->assertInstanceOf(UserModel::class, $result);
     }
 
-    public function testCreatesInvalid()
+    public function testCreatesInvalid(): void
     {
         $result = Factories::widgets('gfnusvjai', ['getShared' => false]);
 
         $this->assertNull($result);
     }
 
-    public function testIgnoresNonClass()
+    public function testIgnoresNonClass(): void
     {
         $result = Factories::widgets('NopeWidget', ['getShared' => false]);
 
         $this->assertNull($result);
     }
 
-    public function testReturnsSharedInstance()
+    public function testReturnsSharedInstance(): void
     {
         $widget1 = Factories::widgets('SomeWidget');
         $widget2 = Factories::widgets(SomeWidget::class);
@@ -187,7 +187,7 @@ public function testReturnsSharedInstance()
         $this->assertSame($widget1, $widget2);
     }
 
-    public function testInjection()
+    public function testInjection(): void
     {
         Factories::injectMock('widgets', 'Banana', new stdClass());
 
@@ -196,7 +196,7 @@ public function testInjection()
         $this->assertInstanceOf('stdClass', $result);
     }
 
-    public function testRespectsComponentAlias()
+    public function testRespectsComponentAlias(): void
     {
         Factories::setOptions('tedwigs', ['component' => 'widgets']);
 
@@ -204,7 +204,7 @@ public function testRespectsComponentAlias()
         $this->assertInstanceOf(SomeWidget::class, $result);
     }
 
-    public function testRespectsPath()
+    public function testRespectsPath(): void
     {
         Factories::setOptions('models', ['path' => 'Widgets']);
 
@@ -212,7 +212,7 @@ public function testRespectsPath()
         $this->assertInstanceOf(SomeWidget::class, $result);
     }
 
-    public function testRespectsInstanceOf()
+    public function testRespectsInstanceOf(): void
     {
         Factories::setOptions('widgets', ['instanceOf' => 'stdClass']);
 
@@ -223,7 +223,7 @@ public function testRespectsInstanceOf()
         $this->assertNull($result);
     }
 
-    public function testSharedRespectsInstanceOf()
+    public function testSharedRespectsInstanceOf(): void
     {
         Factories::injectMock('widgets', 'SomeWidget', new OtherWidget());
 
@@ -231,7 +231,7 @@ public function testSharedRespectsInstanceOf()
         $this->assertInstanceOf(SomeWidget::class, $result);
     }
 
-    public function testPrioritizesParameterOptions()
+    public function testPrioritizesParameterOptions(): void
     {
         Factories::setOptions('widgets', ['instanceOf' => 'stdClass']);
 
@@ -239,7 +239,7 @@ public function testPrioritizesParameterOptions()
         $this->assertInstanceOf(OtherWidget::class, $result);
     }
 
-    public function testFindsAppFirst()
+    public function testFindsAppFirst(): void
     {
         // Create a fake class in App
         $class = 'App\Widgets\OtherWidget';
@@ -251,7 +251,7 @@ class_alias(SomeWidget::class, $class);
         $this->assertInstanceOf(SomeWidget::class, $result);
     }
 
-    public function testpreferAppOverridesClassname()
+    public function testpreferAppOverridesClassname(): void
     {
         // Create a fake class in App
         $class = 'App\Widgets\OtherWidget';
diff --git a/tests/system/Config/MimesTest.php b/tests/system/Config/MimesTest.php
index 1ff85dffefec..7e1e78676155 100644
--- a/tests/system/Config/MimesTest.php
+++ b/tests/system/Config/MimesTest.php
@@ -50,7 +50,7 @@ public function extensionsList(): iterable
     /**
      * @dataProvider extensionsList
      */
-    public function testGuessExtensionFromType(?string $expected, string $mime)
+    public function testGuessExtensionFromType(?string $expected, string $mime): void
     {
         $this->assertSame($expected, Mimes::guessExtensionFromType($mime));
     }
@@ -84,7 +84,7 @@ public function mimesList(): iterable
     /**
      * @dataProvider mimesList
      */
-    public function testGuessTypeFromExtension(?string $expected, string $ext)
+    public function testGuessTypeFromExtension(?string $expected, string $ext): void
     {
         $this->assertSame($expected, Mimes::guessTypeFromExtension($ext));
     }
diff --git a/tests/system/Config/ServicesTest.php b/tests/system/Config/ServicesTest.php
index 143591aac10c..36e97ba1ed2c 100644
--- a/tests/system/Config/ServicesTest.php
+++ b/tests/system/Config/ServicesTest.php
@@ -70,7 +70,7 @@ protected function tearDown(): void
         $this->resetServices();
     }
 
-    public function testCanReplaceFrameworkServices()
+    public function testCanReplaceFrameworkServices(): void
     {
         $this->expectException(RuntimeException::class);
         $this->expectExceptionMessage('Service originated from Tests\Support\Config\Services');
@@ -78,97 +78,97 @@ public function testCanReplaceFrameworkServices()
         Services::uri('testCanReplaceFrameworkServices');
     }
 
-    public function testNewAutoloader()
+    public function testNewAutoloader(): void
     {
         $actual = Services::autoloader();
         $this->assertInstanceOf(Autoloader::class, $actual);
     }
 
-    public function testNewUnsharedAutoloader()
+    public function testNewUnsharedAutoloader(): void
     {
         $actual = Services::autoloader(false);
         $this->assertInstanceOf(Autoloader::class, $actual);
     }
 
-    public function testNewFileLocator()
+    public function testNewFileLocator(): void
     {
         $actual = Services::locator();
         $this->assertInstanceOf(FileLocator::class, $actual);
     }
 
-    public function testNewUnsharedFileLocator()
+    public function testNewUnsharedFileLocator(): void
     {
         $actual = Services::locator(false);
         $this->assertInstanceOf(FileLocator::class, $actual);
     }
 
-    public function testNewCurlRequest()
+    public function testNewCurlRequest(): void
     {
         $actual = Services::curlrequest();
         $this->assertInstanceOf(CURLRequest::class, $actual);
     }
 
-    public function testNewEmail()
+    public function testNewEmail(): void
     {
         $actual = Services::email();
         $this->assertInstanceOf(Email::class, $actual);
     }
 
-    public function testNewUnsharedEmailWithEmptyConfig()
+    public function testNewUnsharedEmailWithEmptyConfig(): void
     {
         $actual = Services::email(null, false);
         $this->assertInstanceOf(Email::class, $actual);
     }
 
-    public function testNewUnsharedEmailWithNonEmptyConfig()
+    public function testNewUnsharedEmailWithNonEmptyConfig(): void
     {
         $actual = Services::email(new \Config\Email(), false);
         $this->assertInstanceOf(Email::class, $actual);
     }
 
-    public function testNewExceptions()
+    public function testNewExceptions(): void
     {
         $actual = Services::exceptions(new Exceptions(), Services::request(), Services::response());
         $this->assertInstanceOf(\CodeIgniter\Debug\Exceptions::class, $actual);
     }
 
-    public function testNewExceptionsWithNullConfig()
+    public function testNewExceptionsWithNullConfig(): void
     {
         $actual = Services::exceptions(null, null, null, false);
         $this->assertInstanceOf(\CodeIgniter\Debug\Exceptions::class, $actual);
     }
 
-    public function testNewIterator()
+    public function testNewIterator(): void
     {
         $actual = Services::iterator();
         $this->assertInstanceOf(Iterator::class, $actual);
     }
 
-    public function testNewImage()
+    public function testNewImage(): void
     {
         $actual = Services::image();
         $this->assertInstanceOf(ImageHandlerInterface::class, $actual);
     }
 
-    public function testNewNegotiatorWithNullConfig()
+    public function testNewNegotiatorWithNullConfig(): void
     {
         $actual = Services::negotiator(null);
         $this->assertInstanceOf(Negotiate::class, $actual);
     }
 
-    public function testNewClirequest()
+    public function testNewClirequest(): void
     {
         $actual = Services::clirequest(null);
         $this->assertInstanceOf(CLIRequest::class, $actual);
     }
 
-    public function testNewUnsharedClirequest()
+    public function testNewUnsharedClirequest(): void
     {
         $actual = Services::clirequest(null, false);
         $this->assertInstanceOf(CLIRequest::class, $actual);
     }
 
-    public function testNewLanguage()
+    public function testNewLanguage(): void
     {
         $actual = Services::language();
         $this->assertInstanceOf(Language::class, $actual);
@@ -178,7 +178,7 @@ public function testNewLanguage()
         $this->assertSame('la', $actual->getLocale());
     }
 
-    public function testNewUnsharedLanguage()
+    public function testNewUnsharedLanguage(): void
     {
         $actual = Services::language(null, false);
         $this->assertInstanceOf(Language::class, $actual);
@@ -188,49 +188,49 @@ public function testNewUnsharedLanguage()
         $this->assertSame('en', $actual->getLocale());
     }
 
-    public function testNewPager()
+    public function testNewPager(): void
     {
         $actual = Services::pager(null);
         $this->assertInstanceOf(Pager::class, $actual);
     }
 
-    public function testNewThrottlerFromShared()
+    public function testNewThrottlerFromShared(): void
     {
         $actual = Services::throttler();
         $this->assertInstanceOf(Throttler::class, $actual);
     }
 
-    public function testNewThrottler()
+    public function testNewThrottler(): void
     {
         $actual = Services::throttler(false);
         $this->assertInstanceOf(Throttler::class, $actual);
     }
 
-    public function testNewToolbar()
+    public function testNewToolbar(): void
     {
         $actual = Services::toolbar(null);
         $this->assertInstanceOf(Toolbar::class, $actual);
     }
 
-    public function testNewUri()
+    public function testNewUri(): void
     {
         $actual = Services::uri(null);
         $this->assertInstanceOf(URI::class, $actual);
     }
 
-    public function testNewValidation()
+    public function testNewValidation(): void
     {
         $actual = Services::validation(null);
         $this->assertInstanceOf(Validation::class, $actual);
     }
 
-    public function testNewViewcellFromShared()
+    public function testNewViewcellFromShared(): void
     {
         $actual = Services::viewcell();
         $this->assertInstanceOf(Cell::class, $actual);
     }
 
-    public function testNewViewcell()
+    public function testNewViewcell(): void
     {
         $actual = Services::viewcell(false);
         $this->assertInstanceOf(Cell::class, $actual);
@@ -240,7 +240,7 @@ public function testNewViewcell()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testNewSession()
+    public function testNewSession(): void
     {
         $actual = Services::session($this->config);
         $this->assertInstanceOf(Session::class, $actual);
@@ -250,7 +250,7 @@ public function testNewSession()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testNewSessionWithNullConfig()
+    public function testNewSessionWithNullConfig(): void
     {
         $actual = Services::session(null, false);
         $this->assertInstanceOf(Session::class, $actual);
@@ -260,7 +260,7 @@ public function testNewSessionWithNullConfig()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testCallStatic()
+    public function testCallStatic(): void
     {
         // __callStatic should kick in for this but fail
         $actual = Services::SeSsIoNs(null, false);
@@ -274,7 +274,7 @@ public function testCallStatic()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testCallStaticDirectly()
+    public function testCallStaticDirectly(): void
     {
         //      $actual = \CodeIgniter\Config\Services::SeSsIoN(null, false); // original
         $actual = Services::__callStatic('SeSsIoN', [null, false]);
@@ -285,7 +285,7 @@ public function testCallStaticDirectly()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testMockInjection()
+    public function testMockInjection(): void
     {
         Services::injectMock('response', new MockResponse(new App()));
         $response = service('response');
@@ -307,7 +307,7 @@ public function testMockInjection()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testReset()
+    public function testReset(): void
     {
         Services::injectMock('response', new MockResponse(new App()));
         $response = service('response');
@@ -326,7 +326,7 @@ public function testReset()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testResetSingle()
+    public function testResetSingle(): void
     {
         Services::injectMock('response', new MockResponse(new App()));
         Services::injectMock('security', new MockSecurity(new App()));
@@ -346,7 +346,7 @@ public function testResetSingle()
         $this->assertSame($security, $security2);
     }
 
-    public function testResetSingleCaseInsensitive()
+    public function testResetSingleCaseInsensitive(): void
     {
         Services::injectMock('response', new MockResponse(new App()));
         $someService = service('response');
@@ -357,59 +357,59 @@ public function testResetSingleCaseInsensitive()
         $this->assertNotInstanceOf(MockResponse::class, $someService);
     }
 
-    public function testFilters()
+    public function testFilters(): void
     {
         $result = Services::filters();
         $this->assertInstanceOf(Filters::class, $result);
     }
 
-    public function testFormat()
+    public function testFormat(): void
     {
         $this->assertInstanceOf(Format::class, Services::format());
     }
 
-    public function testUnsharedFormat()
+    public function testUnsharedFormat(): void
     {
         $this->assertInstanceOf(Format::class, Services::format(null, false));
     }
 
-    public function testHoneypot()
+    public function testHoneypot(): void
     {
         $result = Services::honeypot();
         $this->assertInstanceOf(Honeypot::class, $result);
     }
 
-    public function testMigrations()
+    public function testMigrations(): void
     {
         $result = Services::migrations();
         $this->assertInstanceOf(MigrationRunner::class, $result);
     }
 
-    public function testParser()
+    public function testParser(): void
     {
         $result = Services::parser();
         $this->assertInstanceOf(Parser::class, $result);
     }
 
-    public function testRedirectResponse()
+    public function testRedirectResponse(): void
     {
         $result = Services::redirectResponse();
         $this->assertInstanceOf(RedirectResponse::class, $result);
     }
 
-    public function testRoutes()
+    public function testRoutes(): void
     {
         $result = Services::routes();
         $this->assertInstanceOf(RouteCollection::class, $result);
     }
 
-    public function testRouter()
+    public function testRouter(): void
     {
         $result = Services::router();
         $this->assertInstanceOf(Router::class, $result);
     }
 
-    public function testSecurity()
+    public function testSecurity(): void
     {
         Services::injectMock('security', new MockSecurity(new App()));
 
@@ -417,19 +417,19 @@ public function testSecurity()
         $this->assertInstanceOf(Security::class, $result);
     }
 
-    public function testTimer()
+    public function testTimer(): void
     {
         $result = Services::timer();
         $this->assertInstanceOf(Timer::class, $result);
     }
 
-    public function testTypography()
+    public function testTypography(): void
     {
         $result = Services::typography();
         $this->assertInstanceOf(Typography::class, $result);
     }
 
-    public function testServiceInstance()
+    public function testServiceInstance(): void
     {
         rename(COMPOSER_PATH, COMPOSER_PATH . '.backup');
         $this->assertInstanceOf(\Config\Services::class, new \Config\Services());
diff --git a/tests/system/ControllerTest.php b/tests/system/ControllerTest.php
index 00c03a5abc0e..c330cde160c2 100644
--- a/tests/system/ControllerTest.php
+++ b/tests/system/ControllerTest.php
@@ -62,7 +62,7 @@ protected function setUp(): void
         $this->logger   = Services::logger();
     }
 
-    public function testConstructor()
+    public function testConstructor(): void
     {
         // make sure we can instantiate one
         $this->controller = new Controller();
@@ -70,7 +70,7 @@ public function testConstructor()
         $this->assertInstanceOf(Controller::class, $this->controller);
     }
 
-    public function testConstructorHTTPS()
+    public function testConstructorHTTPS(): void
     {
         $original = $_SERVER;
         $_SERVER  = ['HTTPS' => 'on'];
@@ -84,7 +84,7 @@ public function testConstructorHTTPS()
         $_SERVER = $original; // restore so code coverage doesn't break
     }
 
-    public function testCachePage()
+    public function testCachePage(): void
     {
         $this->controller = new Controller();
         $this->controller->initController($this->request, $this->response, $this->logger);
@@ -93,7 +93,7 @@ public function testCachePage()
         $this->assertNull($method(10));
     }
 
-    public function testValidate()
+    public function testValidate(): void
     {
         // make sure we can instantiate one
         $this->controller = new Controller();
@@ -104,7 +104,7 @@ public function testValidate()
         $this->assertFalse($method([]));
     }
 
-    public function testValidateWithStringRulesNotFound()
+    public function testValidateWithStringRulesNotFound(): void
     {
         $this->expectException(ValidationException::class);
 
@@ -116,7 +116,7 @@ public function testValidateWithStringRulesNotFound()
         $this->assertFalse($method('signup'));
     }
 
-    public function testValidateWithStringRulesFoundReadMessagesFromValidationConfig()
+    public function testValidateWithStringRulesFoundReadMessagesFromValidationConfig(): void
     {
         $validation = new class () extends ValidationConfig {
             public $signup = [
@@ -139,7 +139,7 @@ public function testValidateWithStringRulesFoundReadMessagesFromValidationConfig
         $this->assertSame('You must choose a username.', Services::validation()->getError('username'));
     }
 
-    public function testValidateWithStringRulesFoundUseMessagesParameter()
+    public function testValidateWithStringRulesFoundUseMessagesParameter(): void
     {
         $validation = new class () extends ValidationConfig {
             public $signup = [
@@ -161,7 +161,7 @@ public function testValidateWithStringRulesFoundUseMessagesParameter()
         $this->assertSame('You must choose a username.', Services::validation()->getError('username'));
     }
 
-    public function testValidateData()
+    public function testValidateData(): void
     {
         // make sure we can instantiate one
         $this->controller = new Controller();
@@ -184,7 +184,7 @@ public function testValidateData()
         );
     }
 
-    public function testHelpers()
+    public function testHelpers(): void
     {
         $this->controller = new class () extends Controller {
             protected $helpers = [
diff --git a/tests/system/Database/BaseConnectionTest.php b/tests/system/Database/BaseConnectionTest.php
index ee59f55d6f2a..333a81c87d1f 100644
--- a/tests/system/Database/BaseConnectionTest.php
+++ b/tests/system/Database/BaseConnectionTest.php
@@ -60,7 +60,7 @@ final class BaseConnectionTest extends CIUnitTestCase
         'failover' => [],
     ];
 
-    public function testSavesConfigOptions()
+    public function testSavesConfigOptions(): void
     {
         $db = new MockConnection($this->options);
 
@@ -80,7 +80,7 @@ public function testSavesConfigOptions()
         $this->assertSame([], $db->failover);
     }
 
-    public function testConnectionThrowExceptionWhenCannotConnect()
+    public function testConnectionThrowExceptionWhenCannotConnect(): void
     {
         try {
             $db = new MockConnection($this->options);
@@ -91,7 +91,7 @@ public function testConnectionThrowExceptionWhenCannotConnect()
         }
     }
 
-    public function testCanConnectAndStoreConnection()
+    public function testCanConnectAndStoreConnection(): void
     {
         $db = new MockConnection($this->options);
         $db->shouldReturn('connect', 123)->initialize();
@@ -99,7 +99,7 @@ public function testCanConnectAndStoreConnection()
         $this->assertSame(123, $db->getConnection());
     }
 
-    public function testCanConnectToFailoverWhenNoConnectionAvailable()
+    public function testCanConnectToFailoverWhenNoConnectionAvailable(): void
     {
         $options             = $this->options;
         $options['failover'] = [$this->failoverOptions];
@@ -114,7 +114,7 @@ public function testCanConnectToFailoverWhenNoConnectionAvailable()
         $this->assertSame('failover', $db->username);
     }
 
-    public function testStoresConnectionTimings()
+    public function testStoresConnectionTimings(): void
     {
         $start = microtime(true);
 
@@ -128,35 +128,35 @@ public function testStoresConnectionTimings()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5535
      */
-    public function testStoresConnectionTimingsNotConnected()
+    public function testStoresConnectionTimingsNotConnected(): void
     {
         $db = new MockConnection($this->options);
 
         $this->assertSame('0.000000', $db->getConnectDuration());
     }
 
-    public function testMagicIssetTrue()
+    public function testMagicIssetTrue(): void
     {
         $db = new MockConnection($this->options);
 
         $this->assertTrue(isset($db->charset));
     }
 
-    public function testMagicIssetFalse()
+    public function testMagicIssetFalse(): void
     {
         $db = new MockConnection($this->options);
 
         $this->assertFalse(isset($db->foobar));
     }
 
-    public function testMagicGet()
+    public function testMagicGet(): void
     {
         $db = new MockConnection($this->options);
 
         $this->assertSame('utf8', $db->charset);
     }
 
-    public function testMagicGetMissing()
+    public function testMagicGetMissing(): void
     {
         $db = new MockConnection($this->options);
 
@@ -175,7 +175,7 @@ public function testProtectIdentifiers(
         bool $fieldExists,
         string $item,
         string $expected
-    ) {
+    ): void {
         $db = new MockConnection($this->options);
 
         $return = $db->protectIdentifiers($item, $prefixSingle, $protectIdentifiers, $fieldExists);
diff --git a/tests/system/Database/BaseQueryTest.php b/tests/system/Database/BaseQueryTest.php
index c25d1cefec69..d52df3899ea6 100644
--- a/tests/system/Database/BaseQueryTest.php
+++ b/tests/system/Database/BaseQueryTest.php
@@ -29,7 +29,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testQueryStoresSQL()
+    public function testQueryStoresSQL(): void
     {
         $query = new Query($this->db);
 
@@ -40,7 +40,7 @@ public function testQueryStoresSQL()
         $this->assertSame($sql, $query->getQuery());
     }
 
-    public function testStoresDuration()
+    public function testStoresDuration(): void
     {
         $query = new Query($this->db);
 
@@ -51,7 +51,7 @@ public function testStoresDuration()
         $this->assertSame(5, (int) $query->getDuration());
     }
 
-    public function testGetStartTime()
+    public function testGetStartTime(): void
     {
         $query = new Query($this->db);
 
@@ -62,7 +62,7 @@ public function testGetStartTime()
         $this->assertSame($start, $query->getStartTime(true));
     }
 
-    public function testGetStartTimeNumberFormat()
+    public function testGetStartTimeNumberFormat(): void
     {
         $query = new Query($this->db);
 
@@ -73,7 +73,7 @@ public function testGetStartTimeNumberFormat()
         $this->assertSame(number_format($start, 6), $query->getStartTime());
     }
 
-    public function testsStoresErrorInformation()
+    public function testsStoresErrorInformation(): void
     {
         $query = new Query($this->db);
 
@@ -88,7 +88,7 @@ public function testsStoresErrorInformation()
         $this->assertSame($msg, $query->getErrorMessage());
     }
 
-    public function testSwapPrefix()
+    public function testSwapPrefix(): void
     {
         $query = new Query($this->db);
 
@@ -188,7 +188,7 @@ public function queryTypes(): iterable
      * @param mixed $expected
      * @param mixed $sql
      */
-    public function testIsWriteType($expected, $sql)
+    public function testIsWriteType($expected, $sql): void
     {
         $query = new Query($this->db);
 
@@ -196,7 +196,7 @@ public function testIsWriteType($expected, $sql)
         $this->assertSame($expected, $query->isWriteType());
     }
 
-    public function testSingleBindingOutsideOfArray()
+    public function testSingleBindingOutsideOfArray(): void
     {
         $query = new Query($this->db);
 
@@ -207,7 +207,7 @@ public function testSingleBindingOutsideOfArray()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testBindingSingleElementInArray()
+    public function testBindingSingleElementInArray(): void
     {
         $query = new Query($this->db);
 
@@ -218,7 +218,7 @@ public function testBindingSingleElementInArray()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testBindingMultipleItems()
+    public function testBindingMultipleItems(): void
     {
         $query = new Query($this->db);
 
@@ -229,7 +229,7 @@ public function testBindingMultipleItems()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testBindingAutoEscapesParameters()
+    public function testBindingAutoEscapesParameters(): void
     {
         $query = new Query($this->db);
 
@@ -243,7 +243,7 @@ public function testBindingAutoEscapesParameters()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5114
      */
-    public function testBindingWithTwoColons()
+    public function testBindingWithTwoColons(): void
     {
         $query = new Query($this->db);
 
@@ -257,7 +257,7 @@ public function testBindingWithTwoColons()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testNamedBinds()
+    public function testNamedBinds(): void
     {
         $query = new Query($this->db);
 
@@ -271,7 +271,7 @@ public function testNamedBinds()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3566
      */
-    public function testNamedBindsWithColonElsewhere()
+    public function testNamedBindsWithColonElsewhere(): void
     {
         $query = new Query($this->db);
         $query->setQuery('SELECT `email`, @total:=(total+1) FROM `users` WHERE `id` = :id:', ['id' => 10]);
@@ -283,7 +283,7 @@ public function testNamedBindsWithColonElsewhere()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/pull/5138
      */
-    public function testNamedBindsWithBindMarkerElsewhere()
+    public function testNamedBindsWithBindMarkerElsewhere(): void
     {
         $query = new Query($this->db);
         $query->setQuery('SELECT * FROM posts WHERE id = :id: AND title = \'The default bind marker is "?"\'', ['id' => 10]);
@@ -295,7 +295,7 @@ public function testNamedBindsWithBindMarkerElsewhere()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/pull/5138
      */
-    public function testSimpleBindsWithNamedBindPlaceholderElsewhere()
+    public function testSimpleBindsWithNamedBindPlaceholderElsewhere(): void
     {
         $query = new Query($this->db);
         $query->setQuery('SELECT * FROM posts WHERE id = ? AND title = \'A named bind placeholder looks like ":foobar:"\'', 10);
@@ -307,7 +307,7 @@ public function testSimpleBindsWithNamedBindPlaceholderElsewhere()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/201
      */
-    public function testSimilarNamedBinds()
+    public function testSimilarNamedBinds(): void
     {
         $query = new Query($this->db);
 
@@ -318,7 +318,7 @@ public function testSimilarNamedBinds()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testNamedBindsDontGetReplacedAgain()
+    public function testNamedBindsDontGetReplacedAgain(): void
     {
         $query = new Query($this->db);
 
@@ -335,7 +335,7 @@ public function testNamedBindsDontGetReplacedAgain()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1705
      */
-    public function testSetQueryBindsWithSetEscapeTrue()
+    public function testSetQueryBindsWithSetEscapeTrue(): void
     {
         $query = new Query($this->db);
 
@@ -349,7 +349,7 @@ public function testSetQueryBindsWithSetEscapeTrue()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1705
      */
-    public function testSetQueryBindsWithSetEscapeFalse()
+    public function testSetQueryBindsWithSetEscapeFalse(): void
     {
         $query = new Query($this->db);
 
@@ -372,7 +372,7 @@ public function testSetQueryBindsWithSetEscapeFalse()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4973
      */
-    public function testSetQueryBindsWithSetEscapeNegativeIntegers()
+    public function testSetQueryBindsWithSetEscapeNegativeIntegers(): void
     {
         $query = new Query($this->db);
 
@@ -387,7 +387,7 @@ public function testSetQueryBindsWithSetEscapeNegativeIntegers()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSetQueryNamedBindsWithNegativeIntegers()
+    public function testSetQueryNamedBindsWithNegativeIntegers(): void
     {
         $query = new Query($this->db);
 
@@ -404,7 +404,7 @@ public function testSetQueryNamedBindsWithNegativeIntegers()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2762
      */
-    public function testSetQueryBinds()
+    public function testSetQueryBinds(): void
     {
         $query = new Query($this->db);
 
@@ -420,7 +420,7 @@ public function testSetQueryBinds()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testGetQueryMultipleTimes()
+    public function testGetQueryMultipleTimes(): void
     {
         $query = new Query($this->db);
 
@@ -434,7 +434,7 @@ public function testGetQueryMultipleTimes()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSetBindsMultipleTimes()
+    public function testSetBindsMultipleTimes(): void
     {
         $query = new Query($this->db);
 
@@ -450,7 +450,7 @@ public function testSetBindsMultipleTimes()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSetQueryMultipleTimesKeepingBinds()
+    public function testSetQueryMultipleTimesKeepingBinds(): void
     {
         $query = new Query($this->db);
 
@@ -466,7 +466,7 @@ public function testSetQueryMultipleTimesKeepingBinds()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSetQueryMultipleTimesReplacingBinds()
+    public function testSetQueryMultipleTimesReplacingBinds(): void
     {
         $query = new Query($this->db);
 
@@ -482,7 +482,7 @@ public function testSetQueryMultipleTimesReplacingBinds()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSetQueryMultipleTimesRemovingBinds()
+    public function testSetQueryMultipleTimesRemovingBinds(): void
     {
         $query = new Query($this->db);
 
@@ -498,7 +498,7 @@ public function testSetQueryMultipleTimesRemovingBinds()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSwapPrefixMultipleTimes()
+    public function testSwapPrefixMultipleTimes(): void
     {
         $query = new Query($this->db);
 
@@ -516,7 +516,7 @@ public function testSwapPrefixMultipleTimes()
         $this->assertSame($newSQL, $query->getQuery());
     }
 
-    public function testSwapPrefixBeforeSetBinds()
+    public function testSwapPrefixBeforeSetBinds(): void
     {
         $query = new Query($this->db);
 
@@ -531,7 +531,7 @@ public function testSwapPrefixBeforeSetBinds()
         $this->assertSame($newSQL, $query->getQuery());
     }
 
-    public function testSwapPrefixAfterSetBinds()
+    public function testSwapPrefixAfterSetBinds(): void
     {
         $query = new Query($this->db);
 
@@ -546,7 +546,7 @@ public function testSwapPrefixAfterSetBinds()
         $this->assertSame($newSQL, $query->getQuery());
     }
 
-    public function testSwapPrefixIsAppliedBeforeBinds()
+    public function testSwapPrefixIsAppliedBeforeBinds(): void
     {
         $query = new Query($this->db);
 
@@ -561,7 +561,7 @@ public function testSwapPrefixIsAppliedBeforeBinds()
         $this->assertSame($newSQL, $query->getQuery());
     }
 
-    public function testSwapPrefixAfterGetQuery()
+    public function testSwapPrefixAfterGetQuery(): void
     {
         $query = new Query($this->db);
 
@@ -601,7 +601,7 @@ public function queryKeywords(): iterable
      * @param mixed $expected
      * @param mixed $sql
      */
-    public function testHighlightQueryKeywords($expected, $sql)
+    public function testHighlightQueryKeywords($expected, $sql): void
     {
         $query = new Query($this->db);
         $query->setQuery($sql);
diff --git a/tests/system/Database/Builder/AliasTest.php b/tests/system/Database/Builder/AliasTest.php
index 02c27aeca8e7..e715ab026c4a 100644
--- a/tests/system/Database/Builder/AliasTest.php
+++ b/tests/system/Database/Builder/AliasTest.php
@@ -30,7 +30,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testAlias()
+    public function testAlias(): void
     {
         $builder = $this->db->table('jobs j');
 
@@ -39,7 +39,7 @@ public function testAlias()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testAliasSupportsArrayOfNames()
+    public function testAliasSupportsArrayOfNames(): void
     {
         $builder = $this->db->table(['jobs j', 'users u']);
 
@@ -48,7 +48,7 @@ public function testAliasSupportsArrayOfNames()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testAliasSupportsStringOfNames()
+    public function testAliasSupportsStringOfNames(): void
     {
         $builder = $this->db->table('jobs j, users u');
 
@@ -60,7 +60,7 @@ public function testAliasSupportsStringOfNames()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1599
      */
-    public function testAliasLeftJoinWithShortTableName()
+    public function testAliasLeftJoinWithShortTableName(): void
     {
         $this->setPrivateProperty($this->db, 'DBPrefix', 'db_');
         $builder = $this->db->table('jobs');
@@ -75,7 +75,7 @@ public function testAliasLeftJoinWithShortTableName()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1599
      */
-    public function testAliasLeftJoinWithLongTableName()
+    public function testAliasLeftJoinWithLongTableName(): void
     {
         $this->setPrivateProperty($this->db, 'DBPrefix', 'db_');
         $builder = $this->db->table('jobs');
@@ -90,7 +90,7 @@ public function testAliasLeftJoinWithLongTableName()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5360
      */
-    public function testAliasSimpleLikeWithDBPrefix()
+    public function testAliasSimpleLikeWithDBPrefix(): void
     {
         $this->setPrivateProperty($this->db, 'DBPrefix', 'db_');
         $builder = $this->db->table('jobs j');
diff --git a/tests/system/Database/Builder/BaseTest.php b/tests/system/Database/Builder/BaseTest.php
index 4acf7f702ff0..1502d59e7285 100644
--- a/tests/system/Database/Builder/BaseTest.php
+++ b/tests/system/Database/Builder/BaseTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testDbReturnsConnection()
+    public function testDbReturnsConnection(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -40,7 +40,7 @@ public function testDbReturnsConnection()
         $this->assertInstanceOf(MockConnection::class, $result);
     }
 
-    public function testGetTableReturnsTable()
+    public function testGetTableReturnsTable(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -48,7 +48,7 @@ public function testGetTableReturnsTable()
         $this->assertSame('jobs', $result);
     }
 
-    public function testGetTableIgnoresFrom()
+    public function testGetTableIgnoresFrom(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -57,7 +57,7 @@ public function testGetTableIgnoresFrom()
         $this->assertSame('jobs', $result);
     }
 
-    public function testSubquerySameBaseBuilderObject()
+    public function testSubquerySameBaseBuilderObject(): void
     {
         $this->expectException(DatabaseException::class);
         $this->expectExceptionMessage('The subquery cannot be the same object as the main query object.');
diff --git a/tests/system/Database/Builder/CountTest.php b/tests/system/Database/Builder/CountTest.php
index f6f4ead5d3b9..25ef83e5a9dc 100644
--- a/tests/system/Database/Builder/CountTest.php
+++ b/tests/system/Database/Builder/CountTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testCountAll()
+    public function testCountAll(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $builder->testMode();
@@ -41,7 +41,7 @@ public function testCountAll()
         $this->assertSame($expectedSQL, $builder->countAll(true));
     }
 
-    public function testCountAllResults()
+    public function testCountAllResults(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $builder->testMode();
@@ -53,7 +53,7 @@ public function testCountAllResults()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $answer));
     }
 
-    public function testCountAllResultsWithGroupBy()
+    public function testCountAllResultsWithGroupBy(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $builder->groupBy('id');
@@ -69,7 +69,7 @@ public function testCountAllResultsWithGroupBy()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3651
      */
-    public function testCountAllResultsWithGroupByAndPrefix()
+    public function testCountAllResultsWithGroupByAndPrefix(): void
     {
         $this->db = new MockConnection(['DBPrefix' => 'ci_']);
 
@@ -86,7 +86,7 @@ public function testCountAllResultsWithGroupByAndPrefix()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $answer2));
     }
 
-    public function testCountAllResultsWithGroupByAndHaving()
+    public function testCountAllResultsWithGroupByAndHaving(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $builder->groupBy('id');
@@ -100,7 +100,7 @@ public function testCountAllResultsWithGroupByAndHaving()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $answer));
     }
 
-    public function testCountAllResultsWithHavingOnly()
+    public function testCountAllResultsWithHavingOnly(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $builder->having('1=1');
diff --git a/tests/system/Database/Builder/DeleteTest.php b/tests/system/Database/Builder/DeleteTest.php
index f2452f9eb28d..8c603b02e662 100644
--- a/tests/system/Database/Builder/DeleteTest.php
+++ b/tests/system/Database/Builder/DeleteTest.php
@@ -30,7 +30,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -48,7 +48,7 @@ public function testDelete()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testGetCompiledDelete()
+    public function testGetCompiledDelete(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -62,7 +62,7 @@ public function testGetCompiledDelete()
         $this->assertSame($expectedSQL, $sql);
     }
 
-    public function testGetCompiledDeleteWithTableAlias()
+    public function testGetCompiledDeleteWithTableAlias(): void
     {
         $builder = $this->db->table('jobs j');
 
@@ -76,7 +76,7 @@ public function testGetCompiledDeleteWithTableAlias()
         $this->assertSame($expectedSQL, $sql);
     }
 
-    public function testGetCompiledDeleteWithLimit()
+    public function testGetCompiledDeleteWithLimit(): void
     {
         $builder = $this->db->table('jobs');
 
diff --git a/tests/system/Database/Builder/DistinctTest.php b/tests/system/Database/Builder/DistinctTest.php
index de574c795df4..939a58b7737c 100644
--- a/tests/system/Database/Builder/DistinctTest.php
+++ b/tests/system/Database/Builder/DistinctTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
diff --git a/tests/system/Database/Builder/EmptyTest.php b/tests/system/Database/Builder/EmptyTest.php
index 008b26bf1676..03e810f495cb 100644
--- a/tests/system/Database/Builder/EmptyTest.php
+++ b/tests/system/Database/Builder/EmptyTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testEmptyWithNoTable()
+    public function testEmptyWithNoTable(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
diff --git a/tests/system/Database/Builder/FromTest.php b/tests/system/Database/Builder/FromTest.php
index 7908346e9bee..560071db18a1 100644
--- a/tests/system/Database/Builder/FromTest.php
+++ b/tests/system/Database/Builder/FromTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testSimpleFrom()
+    public function testSimpleFrom(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -43,7 +43,7 @@ public function testSimpleFrom()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromThatOverwrites()
+    public function testFromThatOverwrites(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -54,7 +54,7 @@ public function testFromThatOverwrites()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromWithMultipleTables()
+    public function testFromWithMultipleTables(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -65,7 +65,7 @@ public function testFromWithMultipleTables()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromWithMultipleTablesAsString()
+    public function testFromWithMultipleTablesAsString(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -76,7 +76,7 @@ public function testFromWithMultipleTablesAsString()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromReset()
+    public function testFromReset(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -103,7 +103,7 @@ public function testFromReset()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromSubquery()
+    public function testFromSubquery(): void
     {
         $expectedSQL = 'SELECT * FROM (SELECT * FROM "users") "alias"';
         $subquery    = new BaseBuilder('users', $this->db);
@@ -124,7 +124,7 @@ public function testFromSubquery()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromWithMultipleTablesAsStringWithSQLSRV()
+    public function testFromWithMultipleTablesAsStringWithSQLSRV(): void
     {
         $this->db = new MockConnection(['DBDriver' => 'SQLSRV', 'database' => 'test', 'schema' => 'dbo']);
 
@@ -137,7 +137,7 @@ public function testFromWithMultipleTablesAsStringWithSQLSRV()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testFromSubqueryWithSQLSRV()
+    public function testFromSubqueryWithSQLSRV(): void
     {
         $this->db = new MockConnection(['DBDriver' => 'SQLSRV', 'database' => 'test', 'schema' => 'dbo']);
 
diff --git a/tests/system/Database/Builder/GetTest.php b/tests/system/Database/Builder/GetTest.php
index e4e641a57875..d787e02f904b 100644
--- a/tests/system/Database/Builder/GetTest.php
+++ b/tests/system/Database/Builder/GetTest.php
@@ -30,7 +30,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testGet()
+    public function testGet(): void
     {
         $builder = $this->db->table('users');
 
@@ -42,7 +42,7 @@ public function testGet()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2141
      */
-    public function testGetWithReset()
+    public function testGetWithReset(): void
     {
         $builder = $this->db->table('users');
         $builder->testMode()->where('username', 'bogus');
@@ -58,7 +58,7 @@ public function testGetWithReset()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2143
      */
-    public function testGetWhereWithLimit()
+    public function testGetWhereWithLimit(): void
     {
         $builder = $this->db->table('users');
         $builder->testMode();
@@ -71,7 +71,7 @@ public function testGetWhereWithLimit()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getWhere(['username' => 'bogus'], 5, null, true)));
     }
 
-    public function testGetWhereWithLimitAndOffset()
+    public function testGetWhereWithLimitAndOffset(): void
     {
         $builder = $this->db->table('users');
         $builder->testMode();
@@ -84,7 +84,7 @@ public function testGetWhereWithLimitAndOffset()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getWhere(['username' => 'bogus'], 5, 10, true)));
     }
 
-    public function testGetWhereWithWhereConditionOnly()
+    public function testGetWhereWithWhereConditionOnly(): void
     {
         $builder = $this->db->table('users');
         $builder->testMode();
@@ -97,7 +97,7 @@ public function testGetWhereWithWhereConditionOnly()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getWhere(['username' => 'bogus'], null, null, true)));
     }
 
-    public function testGetWhereWithoutArgs()
+    public function testGetWhereWithoutArgs(): void
     {
         $builder = $this->db->table('users');
         $builder->testMode();
diff --git a/tests/system/Database/Builder/GroupTest.php b/tests/system/Database/Builder/GroupTest.php
index fab69aa0e554..f5ba8d13f072 100644
--- a/tests/system/Database/Builder/GroupTest.php
+++ b/tests/system/Database/Builder/GroupTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testGroupBy()
+    public function testGroupBy(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -42,7 +42,7 @@ public function testGroupBy()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingBy()
+    public function testHavingBy(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -55,7 +55,7 @@ public function testHavingBy()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingBy()
+    public function testOrHavingBy(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -69,7 +69,7 @@ public function testOrHavingBy()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingIn()
+    public function testHavingIn(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -82,7 +82,7 @@ public function testHavingIn()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingInClosure()
+    public function testHavingInClosure(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -95,7 +95,7 @@ public function testHavingInClosure()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingIn()
+    public function testOrHavingIn(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -109,7 +109,7 @@ public function testOrHavingIn()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingInClosure()
+    public function testOrHavingInClosure(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -123,7 +123,7 @@ public function testOrHavingInClosure()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingNotIn()
+    public function testHavingNotIn(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -136,7 +136,7 @@ public function testHavingNotIn()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingNotInClosure()
+    public function testHavingNotInClosure(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -149,7 +149,7 @@ public function testHavingNotInClosure()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingNotIn()
+    public function testOrHavingNotIn(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -163,7 +163,7 @@ public function testOrHavingNotIn()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingNotInClosure()
+    public function testOrHavingNotInClosure(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -177,7 +177,7 @@ public function testOrHavingNotInClosure()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingLike()
+    public function testHavingLike(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -190,7 +190,7 @@ public function testHavingLike()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingLikeBefore()
+    public function testHavingLikeBefore(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -203,7 +203,7 @@ public function testHavingLikeBefore()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingLikeAfter()
+    public function testHavingLikeAfter(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -216,7 +216,7 @@ public function testHavingLikeAfter()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testNotHavingLike()
+    public function testNotHavingLike(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -229,7 +229,7 @@ public function testNotHavingLike()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testNotHavingLikeBefore()
+    public function testNotHavingLikeBefore(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -242,7 +242,7 @@ public function testNotHavingLikeBefore()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testNotHavingLikeAfter()
+    public function testNotHavingLikeAfter(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -255,7 +255,7 @@ public function testNotHavingLikeAfter()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingLike()
+    public function testOrHavingLike(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -269,7 +269,7 @@ public function testOrHavingLike()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingLikeBefore()
+    public function testOrHavingLikeBefore(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -283,7 +283,7 @@ public function testOrHavingLikeBefore()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrHavingLikeAfter()
+    public function testOrHavingLikeAfter(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -297,7 +297,7 @@ public function testOrHavingLikeAfter()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrNotHavingLike()
+    public function testOrNotHavingLike(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -311,7 +311,7 @@ public function testOrNotHavingLike()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrNotHavingLikeBefore()
+    public function testOrNotHavingLikeBefore(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -325,7 +325,7 @@ public function testOrNotHavingLikeBefore()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrNotHavingLikeAfter()
+    public function testOrNotHavingLikeAfter(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -339,7 +339,7 @@ public function testOrNotHavingLikeAfter()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingAndGroup()
+    public function testHavingAndGroup(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -356,7 +356,7 @@ public function testHavingAndGroup()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testHavingOrGroup()
+    public function testHavingOrGroup(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -373,7 +373,7 @@ public function testHavingOrGroup()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testNotHavingAndGroup()
+    public function testNotHavingAndGroup(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -390,7 +390,7 @@ public function testNotHavingAndGroup()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testNotHavingOrGroup()
+    public function testNotHavingOrGroup(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -407,7 +407,7 @@ public function testNotHavingOrGroup()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testAndGroups()
+    public function testAndGroups(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -422,7 +422,7 @@ public function testAndGroups()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrGroups()
+    public function testOrGroups(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -437,7 +437,7 @@ public function testOrGroups()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testNotGroups()
+    public function testNotGroups(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -452,7 +452,7 @@ public function testNotGroups()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrNotGroups()
+    public function testOrNotGroups(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
diff --git a/tests/system/Database/Builder/InsertTest.php b/tests/system/Database/Builder/InsertTest.php
index b0fc3890cc3c..a9040d871f25 100644
--- a/tests/system/Database/Builder/InsertTest.php
+++ b/tests/system/Database/Builder/InsertTest.php
@@ -37,7 +37,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testInsertArray()
+    public function testInsertArray(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -63,7 +63,7 @@ public function testInsertArray()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testInsertObject()
+    public function testInsertObject(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -89,7 +89,7 @@ public function testInsertObject()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testInsertObjectWithRawSql()
+    public function testInsertObjectWithRawSql(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -107,7 +107,7 @@ public function testInsertObjectWithRawSql()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5365
      */
-    public function testInsertWithTableAlias()
+    public function testInsertWithTableAlias(): void
     {
         $builder = $this->db->table('jobs as j');
 
@@ -133,7 +133,7 @@ public function testInsertWithTableAlias()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testThrowsExceptionOnNoValuesSet()
+    public function testThrowsExceptionOnNoValuesSet(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -143,7 +143,7 @@ public function testThrowsExceptionOnNoValuesSet()
         $builder->testMode()->insert(null, true);
     }
 
-    public function testInsertBatch()
+    public function testInsertBatch(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -178,7 +178,7 @@ public function testInsertBatch()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5671
      */
-    public function testInsertBatchIgnore()
+    public function testInsertBatchIgnore(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -212,7 +212,7 @@ public function testInsertBatchIgnore()
         $this->assertSame($expected, str_replace("\n", ' ', $query->getQuery()));
     }
 
-    public function testInsertBatchWithoutEscape()
+    public function testInsertBatchWithoutEscape(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -242,7 +242,7 @@ public function testInsertBatchWithoutEscape()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4345
      */
-    public function testInsertBatchWithFieldsEndingInNumbers()
+    public function testInsertBatchWithFieldsEndingInNumbers(): void
     {
         $builder = $this->db->table('ip_table');
 
@@ -263,7 +263,7 @@ public function testInsertBatchWithFieldsEndingInNumbers()
         $this->assertSame($expected, str_replace("\n", ' ', $query->getQuery()));
     }
 
-    public function testInsertBatchThrowsExceptionOnNoData()
+    public function testInsertBatchThrowsExceptionOnNoData(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -272,7 +272,7 @@ public function testInsertBatchThrowsExceptionOnNoData()
         $builder->insertBatch();
     }
 
-    public function testInsertBatchThrowsExceptionOnEmptyData()
+    public function testInsertBatchThrowsExceptionOnEmptyData(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -281,7 +281,7 @@ public function testInsertBatchThrowsExceptionOnEmptyData()
         $builder->insertBatch([]);
     }
 
-    public function testSetIncorrectRawSqlUsage()
+    public function testSetIncorrectRawSqlUsage(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage(
diff --git a/tests/system/Database/Builder/JoinTest.php b/tests/system/Database/Builder/JoinTest.php
index b981b8216dc2..bab306db4f88 100644
--- a/tests/system/Database/Builder/JoinTest.php
+++ b/tests/system/Database/Builder/JoinTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testJoinSimple()
+    public function testJoinSimple(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -45,7 +45,7 @@ public function testJoinSimple()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testJoinIsNull()
+    public function testJoinIsNull(): void
     {
         $builder = new BaseBuilder('table1', $this->db);
 
@@ -56,7 +56,7 @@ public function testJoinIsNull()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testJoinIsNotNull()
+    public function testJoinIsNotNull(): void
     {
         $builder = new BaseBuilder('table1', $this->db);
 
@@ -67,7 +67,7 @@ public function testJoinIsNotNull()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testJoinMultipleConditions()
+    public function testJoinMultipleConditions(): void
     {
         $builder = new BaseBuilder('table1', $this->db);
 
@@ -81,7 +81,7 @@ public function testJoinMultipleConditions()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3832
      */
-    public function testJoinRawSql()
+    public function testJoinRawSql(): void
     {
         $builder = new BaseBuilder('device', $this->db);
 
@@ -100,7 +100,7 @@ public function testJoinRawSql()
         $this->assertSame($expectedSQL, $output);
     }
 
-    public function testFullOuterJoin()
+    public function testFullOuterJoin(): void
     {
         $builder = new PostgreBuilder('jobs', $this->db);
         $builder->testMode();
@@ -111,7 +111,7 @@ public function testFullOuterJoin()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testJoinWithAlias()
+    public function testJoinWithAlias(): void
     {
         $this->db = new MockConnection(['DBDriver' => 'SQLSRV', 'database' => 'test', 'schema' => 'dbo']);
 
diff --git a/tests/system/Database/Builder/LikeTest.php b/tests/system/Database/Builder/LikeTest.php
index 23e7943a3b56..2c76c24ef640 100644
--- a/tests/system/Database/Builder/LikeTest.php
+++ b/tests/system/Database/Builder/LikeTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testSimpleLike()
+    public function testSimpleLike(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -53,7 +53,7 @@ public function testSimpleLike()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3970
      */
-    public function testLikeWithRawSql()
+    public function testLikeWithRawSql(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -73,7 +73,7 @@ public function testLikeWithRawSql()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testLikeNoSide()
+    public function testLikeNoSide(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -91,7 +91,7 @@ public function testLikeNoSide()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testLikeBeforeOnly()
+    public function testLikeBeforeOnly(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -109,7 +109,7 @@ public function testLikeBeforeOnly()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testLikeAfterOnly()
+    public function testLikeAfterOnly(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -127,7 +127,7 @@ public function testLikeAfterOnly()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testOrLike()
+    public function testOrLike(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -149,7 +149,7 @@ public function testOrLike()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testNotLike()
+    public function testNotLike(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -167,7 +167,7 @@ public function testNotLike()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testOrNotLike()
+    public function testOrNotLike(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -189,7 +189,7 @@ public function testOrNotLike()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testCaseInsensitiveLike()
+    public function testCaseInsensitiveLike(): void
     {
         $builder = new BaseBuilder('job', $this->db);
 
@@ -210,7 +210,7 @@ public function testCaseInsensitiveLike()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5775
      */
-    public function testDBPrefixAndCoulmnWithTablename()
+    public function testDBPrefixAndCoulmnWithTablename(): void
     {
         $this->db = new MockConnection(['DBPrefix' => 'db_']);
         $builder  = new BaseBuilder('test', $this->db);
diff --git a/tests/system/Database/Builder/LimitTest.php b/tests/system/Database/Builder/LimitTest.php
index 8e552a3442ca..5e636afc6283 100644
--- a/tests/system/Database/Builder/LimitTest.php
+++ b/tests/system/Database/Builder/LimitTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testLimitAlone()
+    public function testLimitAlone(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -42,7 +42,7 @@ public function testLimitAlone()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testLimitAndOffset()
+    public function testLimitAndOffset(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -53,7 +53,7 @@ public function testLimitAndOffset()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testLimitAndOffsetMethod()
+    public function testLimitAndOffsetMethod(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
diff --git a/tests/system/Database/Builder/OrderTest.php b/tests/system/Database/Builder/OrderTest.php
index a848c3f84063..1a8cc4a60359 100644
--- a/tests/system/Database/Builder/OrderTest.php
+++ b/tests/system/Database/Builder/OrderTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testOrderAscending()
+    public function testOrderAscending(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -42,7 +42,7 @@ public function testOrderAscending()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrderDescending()
+    public function testOrderDescending(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -53,7 +53,7 @@ public function testOrderDescending()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrderRandom()
+    public function testOrderRandom(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
@@ -64,7 +64,7 @@ public function testOrderRandom()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrderRandomWithRandomColumn()
+    public function testOrderRandomWithRandomColumn(): void
     {
         $this->db->setPrefix('fail_');
         $builder = new BaseBuilder('user', $this->db);
diff --git a/tests/system/Database/Builder/PrefixTest.php b/tests/system/Database/Builder/PrefixTest.php
index ed914eb62a49..5888eb84f2dd 100644
--- a/tests/system/Database/Builder/PrefixTest.php
+++ b/tests/system/Database/Builder/PrefixTest.php
@@ -31,14 +31,14 @@ protected function setUp(): void
         $this->db = new MockConnection(['DBPrefix' => 'ci_']);
     }
 
-    public function testPrefixesSetOnTableNames()
+    public function testPrefixesSetOnTableNames(): void
     {
         $expected = 'ci_users';
 
         $this->assertSame($expected, $this->db->prefixTable('users'));
     }
 
-    public function testPrefixesSetOnTableNamesWithWhereClause()
+    public function testPrefixesSetOnTableNamesWithWhereClause(): void
     {
         $builder = $this->db->table('users');
 
diff --git a/tests/system/Database/Builder/ReplaceTest.php b/tests/system/Database/Builder/ReplaceTest.php
index a37159f66f16..e90895a6e269 100644
--- a/tests/system/Database/Builder/ReplaceTest.php
+++ b/tests/system/Database/Builder/ReplaceTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testSimpleReplace()
+    public function testSimpleReplace(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -46,7 +46,7 @@ public function testSimpleReplace()
         $this->assertSame($expected, $builder->testMode()->replace($data));
     }
 
-    public function testReplaceThrowsExceptionWithNoData()
+    public function testReplaceThrowsExceptionWithNoData(): void
     {
         $builder = $this->db->table('jobs');
 
diff --git a/tests/system/Database/Builder/SelectTest.php b/tests/system/Database/Builder/SelectTest.php
index af7bf96d119e..b331b33dcae5 100644
--- a/tests/system/Database/Builder/SelectTest.php
+++ b/tests/system/Database/Builder/SelectTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testSimpleSelect()
+    public function testSimpleSelect(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -43,7 +43,7 @@ public function testSimpleSelect()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectOnlyOneColumn()
+    public function testSelectOnlyOneColumn(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -54,7 +54,7 @@ public function testSelectOnlyOneColumn()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectAcceptsArray()
+    public function testSelectAcceptsArray(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -65,7 +65,7 @@ public function testSelectAcceptsArray()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectAcceptsMultipleColumns()
+    public function testSelectAcceptsMultipleColumns(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -76,7 +76,7 @@ public function testSelectAcceptsMultipleColumns()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectKeepsAliases()
+    public function testSelectKeepsAliases(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -87,7 +87,7 @@ public function testSelectKeepsAliases()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectWorksWithComplexSelects()
+    public function testSelectWorksWithComplexSelects(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -101,7 +101,7 @@ public function testSelectWorksWithComplexSelects()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4355
      */
-    public function testSelectWorksWithRawSql()
+    public function testSelectWorksWithRawSql(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -115,7 +115,7 @@ public function testSelectWorksWithRawSql()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4311
      */
-    public function testSelectWorksWithEscpaeFalse()
+    public function testSelectWorksWithEscpaeFalse(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -129,7 +129,7 @@ public function testSelectWorksWithEscpaeFalse()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4355
      */
-    public function testSelectRegularExpressionWorksWithEscpaeFalse()
+    public function testSelectRegularExpressionWorksWithEscpaeFalse(): void
     {
         $builder = new BaseBuilder('ob_human_resources', $this->db);
 
@@ -145,7 +145,7 @@ public function testSelectRegularExpressionWorksWithEscpaeFalse()
         $this->assertSame($expected, $builder->getCompiledSelect());
     }
 
-    public function testSelectMinWithNoAlias()
+    public function testSelectMinWithNoAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -156,7 +156,7 @@ public function testSelectMinWithNoAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectMinWithAlias()
+    public function testSelectMinWithAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -167,7 +167,7 @@ public function testSelectMinWithAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectMaxWithNoAlias()
+    public function testSelectMaxWithNoAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -178,7 +178,7 @@ public function testSelectMaxWithNoAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectMaxWithAlias()
+    public function testSelectMaxWithAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -189,7 +189,7 @@ public function testSelectMaxWithAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectAvgWithNoAlias()
+    public function testSelectAvgWithNoAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -200,7 +200,7 @@ public function testSelectAvgWithNoAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectAvgWithAlias()
+    public function testSelectAvgWithAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -211,7 +211,7 @@ public function testSelectAvgWithAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectSumWithNoAlias()
+    public function testSelectSumWithNoAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -222,7 +222,7 @@ public function testSelectSumWithNoAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectSumWithAlias()
+    public function testSelectSumWithAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -233,7 +233,7 @@ public function testSelectSumWithAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectCountWithNoAlias()
+    public function testSelectCountWithNoAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -244,7 +244,7 @@ public function testSelectCountWithNoAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectCountWithAlias()
+    public function testSelectCountWithAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -255,7 +255,7 @@ public function testSelectCountWithAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectMinThrowsExceptionOnEmptyValue()
+    public function testSelectMinThrowsExceptionOnEmptyValue(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -265,7 +265,7 @@ public function testSelectMinThrowsExceptionOnEmptyValue()
         $builder->selectSum('');
     }
 
-    public function testSelectMaxWithDotNameAndNoAlias()
+    public function testSelectMaxWithDotNameAndNoAlias(): void
     {
         $builder = new BaseBuilder('invoices', $this->db);
 
@@ -276,7 +276,7 @@ public function testSelectMaxWithDotNameAndNoAlias()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectMinThrowsExceptionOnMultipleColumn()
+    public function testSelectMinThrowsExceptionOnMultipleColumn(): void
     {
         $builder = new BaseBuilder('users', $this->db);
 
@@ -286,7 +286,7 @@ public function testSelectMinThrowsExceptionOnMultipleColumn()
         $builder->selectSum('name,role');
     }
 
-    public function testSimpleSelectWithSQLSRV()
+    public function testSimpleSelectWithSQLSRV(): void
     {
         $this->db = new MockConnection(['DBDriver' => 'SQLSRV', 'database' => 'test', 'schema' => 'dbo']);
 
@@ -297,7 +297,7 @@ public function testSimpleSelectWithSQLSRV()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectSubquery()
+    public function testSelectSubquery(): void
     {
         $builder  = new BaseBuilder('users', $this->db);
         $subquery = new BaseBuilder('countries', $this->db);
@@ -310,7 +310,7 @@ public function testSelectSubquery()
         $this->assertSame($expected, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testSelectResetQuery()
+    public function testSelectResetQuery(): void
     {
         $builder = new BaseBuilder('users', $this->db);
         $builder->select('name, role');
diff --git a/tests/system/Database/Builder/TruncateTest.php b/tests/system/Database/Builder/TruncateTest.php
index 433feb089836..6f839860eef5 100644
--- a/tests/system/Database/Builder/TruncateTest.php
+++ b/tests/system/Database/Builder/TruncateTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testTruncate()
+    public function testTruncate(): void
     {
         $builder = new BaseBuilder('user', $this->db);
 
diff --git a/tests/system/Database/Builder/UpdateTest.php b/tests/system/Database/Builder/UpdateTest.php
index a9f77d4d554c..5464cf031480 100644
--- a/tests/system/Database/Builder/UpdateTest.php
+++ b/tests/system/Database/Builder/UpdateTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testUpdateArray()
+    public function testUpdateArray(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -59,7 +59,7 @@ public function testUpdateArray()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateObject()
+    public function testUpdateObject(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -82,7 +82,7 @@ public function testUpdateObject()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateInternalWhereAndLimit()
+    public function testUpdateInternalWhereAndLimit(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -104,7 +104,7 @@ public function testUpdateInternalWhereAndLimit()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateWithSet()
+    public function testUpdateWithSet(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -126,7 +126,7 @@ public function testUpdateWithSet()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateWithSetAsInt()
+    public function testUpdateWithSetAsInt(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -148,7 +148,7 @@ public function testUpdateWithSetAsInt()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateWithSetAsBoolean()
+    public function testUpdateWithSetAsBoolean(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -170,7 +170,7 @@ public function testUpdateWithSetAsBoolean()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateWithSetAsArray()
+    public function testUpdateWithSetAsArray(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -200,7 +200,7 @@ public function testUpdateWithSetAsArray()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateThrowsExceptionWithNoData()
+    public function testUpdateThrowsExceptionWithNoData(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -210,7 +210,7 @@ public function testUpdateThrowsExceptionWithNoData()
         $builder->update(null, null, null);
     }
 
-    public function testUpdateBatch()
+    public function testUpdateBatch(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -248,7 +248,7 @@ public function testUpdateBatch()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testSetUpdateBatchWithoutEscape()
+    public function testSetUpdateBatchWithoutEscape(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $escape  = false;
@@ -287,7 +287,7 @@ public function testSetUpdateBatchWithoutEscape()
         $this->assertSame($expected, $query->getQuery());
     }
 
-    public function testUpdateBatchThrowsExceptionWithNoData()
+    public function testUpdateBatchThrowsExceptionWithNoData(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -297,7 +297,7 @@ public function testUpdateBatchThrowsExceptionWithNoData()
         $builder->updateBatch(null, 'id');
     }
 
-    public function testUpdateBatchThrowsExceptionWithNoID()
+    public function testUpdateBatchThrowsExceptionWithNoID(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -320,7 +320,7 @@ public function testUpdateBatchThrowsExceptionWithNoID()
         $builder->updateBatch($set, null);
     }
 
-    public function testUpdateBatchThrowsExceptionWithEmptySetArray()
+    public function testUpdateBatchThrowsExceptionWithEmptySetArray(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -330,7 +330,7 @@ public function testUpdateBatchThrowsExceptionWithEmptySetArray()
         $builder->updateBatch([], 'id');
     }
 
-    public function testUpdateWithWhereSameColumn()
+    public function testUpdateWithWhereSameColumn(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
 
@@ -352,7 +352,7 @@ public function testUpdateWithWhereSameColumn()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateWithWhereSameColumn2()
+    public function testUpdateWithWhereSameColumn2(): void
     {
         // calling order: set() -> where()
         $builder = new BaseBuilder('jobs', $this->db);
@@ -378,7 +378,7 @@ public function testUpdateWithWhereSameColumn2()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testUpdateWithWhereSameColumn3()
+    public function testUpdateWithWhereSameColumn3(): void
     {
         // calling order: where() -> set() in update()
         $builder = new BaseBuilder('jobs', $this->db);
@@ -406,7 +406,7 @@ public function testUpdateWithWhereSameColumn3()
     /**
      * @see https://codeigniter4.github.io/CodeIgniter4/database/query_builder.html#updating-data
      */
-    public function testSetWithoutEscape()
+    public function testSetWithoutEscape(): void
     {
         $builder = new BaseBuilder('mytable', $this->db);
 
@@ -427,7 +427,7 @@ public function testSetWithoutEscape()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testSetWithAndWithoutEscape()
+    public function testSetWithAndWithoutEscape(): void
     {
         $builder = new BaseBuilder('mytable', $this->db);
 
diff --git a/tests/system/Database/Builder/WhenTest.php b/tests/system/Database/Builder/WhenTest.php
index 69863b844875..dc518e2168e7 100644
--- a/tests/system/Database/Builder/WhenTest.php
+++ b/tests/system/Database/Builder/WhenTest.php
@@ -33,14 +33,14 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testWhenTrue()
+    public function testWhenTrue(): void
     {
         $builder = $this->db->table('jobs');
 
         $expectedSQL = 'SELECT * FROM "jobs"';
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
 
-        $builder = $builder->when(true, static function ($query) {
+        $builder = $builder->when(true, static function ($query): void {
             $query->select('id');
         });
 
@@ -48,11 +48,11 @@ public function testWhenTrue()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenTruthy()
+    public function testWhenTruthy(): void
     {
         $builder = $this->db->table('jobs');
 
-        $builder = $builder->when('abc', static function ($query) {
+        $builder = $builder->when('abc', static function ($query): void {
             $query->select('id');
         });
 
@@ -60,13 +60,13 @@ public function testWhenTruthy()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenRunsDefaultWhenFalse()
+    public function testWhenRunsDefaultWhenFalse(): void
     {
         $builder = $this->db->table('jobs');
 
-        $builder = $builder->when(false, static function ($query) {
+        $builder = $builder->when(false, static function ($query): void {
             $query->select('id');
-        }, static function ($query) {
+        }, static function ($query): void {
             $query->select('name');
         });
 
@@ -74,11 +74,11 @@ public function testWhenRunsDefaultWhenFalse()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenDoesntModifyWhenFalse()
+    public function testWhenDoesntModifyWhenFalse(): void
     {
         $builder = $this->db->table('jobs');
 
-        $builder = $builder->when(false, static function ($query) {
+        $builder = $builder->when(false, static function ($query): void {
             $query->select('id');
         });
 
@@ -86,12 +86,12 @@ public function testWhenDoesntModifyWhenFalse()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenPassesParemeters()
+    public function testWhenPassesParemeters(): void
     {
         $builder = $this->db->table('jobs');
         $name    = 'developer';
 
-        $builder = $builder->when($name, static function ($query, $name) {
+        $builder = $builder->when($name, static function ($query, $name): void {
             $query->where('name', $name);
         });
 
@@ -99,14 +99,14 @@ public function testWhenPassesParemeters()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenNotFalse()
+    public function testWhenNotFalse(): void
     {
         $builder = $this->db->table('jobs');
 
         $expectedSQL = 'SELECT * FROM "jobs"';
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
 
-        $builder = $builder->whenNot(false, static function ($query) {
+        $builder = $builder->whenNot(false, static function ($query): void {
             $query->select('id');
         });
 
@@ -114,11 +114,11 @@ public function testWhenNotFalse()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenNotFalsey()
+    public function testWhenNotFalsey(): void
     {
         $builder = $this->db->table('jobs');
 
-        $builder = $builder->whenNot('0', static function ($query) {
+        $builder = $builder->whenNot('0', static function ($query): void {
             $query->select('id');
         });
 
@@ -126,13 +126,13 @@ public function testWhenNotFalsey()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenNotRunsDefaultWhenTrue()
+    public function testWhenNotRunsDefaultWhenTrue(): void
     {
         $builder = $this->db->table('jobs');
 
-        $builder = $builder->whenNot(true, static function ($query) {
+        $builder = $builder->whenNot(true, static function ($query): void {
             $query->select('id');
-        }, static function ($query) {
+        }, static function ($query): void {
             $query->select('name');
         });
 
@@ -140,11 +140,11 @@ public function testWhenNotRunsDefaultWhenTrue()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenNotDoesntModifyWhenFalse()
+    public function testWhenNotDoesntModifyWhenFalse(): void
     {
         $builder = $this->db->table('jobs');
 
-        $builder = $builder->whenNot(true, static function ($query) {
+        $builder = $builder->whenNot(true, static function ($query): void {
             $query->select('id');
         });
 
@@ -152,12 +152,12 @@ public function testWhenNotDoesntModifyWhenFalse()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhenNotPassesParemeters()
+    public function testWhenNotPassesParemeters(): void
     {
         $builder = $this->db->table('jobs');
         $name    = '0';
 
-        $builder = $builder->whenNot($name, static function ($query, $name) {
+        $builder = $builder->whenNot($name, static function ($query, $name): void {
             $query->where('name', $name);
         });
 
diff --git a/tests/system/Database/Builder/WhereTest.php b/tests/system/Database/Builder/WhereTest.php
index df0a778f3c39..c0ddeb34f329 100644
--- a/tests/system/Database/Builder/WhereTest.php
+++ b/tests/system/Database/Builder/WhereTest.php
@@ -39,7 +39,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testSimpleWhere()
+    public function testSimpleWhere(): void
     {
         $builder = $this->db->table('users');
 
@@ -56,7 +56,7 @@ public function testSimpleWhere()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereNoEscape()
+    public function testWhereNoEscape(): void
     {
         $builder = $this->db->table('users');
 
@@ -73,7 +73,7 @@ public function testWhereNoEscape()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereCustomKeyOperator()
+    public function testWhereCustomKeyOperator(): void
     {
         $builder = $this->db->table('users');
 
@@ -90,7 +90,7 @@ public function testWhereCustomKeyOperator()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereAssociateArray()
+    public function testWhereAssociateArray(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -116,7 +116,7 @@ public function testWhereAssociateArray()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereAssociateArrayKeyHasEqualValueIsNull()
+    public function testWhereAssociateArrayKeyHasEqualValueIsNull(): void
     {
         $builder = $this->db->table('users');
 
@@ -132,7 +132,7 @@ public function testWhereAssociateArrayKeyHasEqualValueIsNull()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereLikeInAssociateArray()
+    public function testWhereLikeInAssociateArray(): void
     {
         $builder = $this->db->table('user');
 
@@ -146,7 +146,7 @@ public function testWhereLikeInAssociateArray()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhereCustomString()
+    public function testWhereCustomString(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -160,7 +160,7 @@ public function testWhereCustomString()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereCustomStringWithOperatorEscapeFalse()
+    public function testWhereCustomStringWithOperatorEscapeFalse(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -174,7 +174,7 @@ public function testWhereCustomStringWithOperatorEscapeFalse()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereCustomStringWithoutOperatorEscapeFalse()
+    public function testWhereCustomStringWithoutOperatorEscapeFalse(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -193,7 +193,7 @@ public function testWhereCustomStringWithoutOperatorEscapeFalse()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereCustomStringWithBetweenEscapeFalse()
+    public function testWhereCustomStringWithBetweenEscapeFalse(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -207,7 +207,7 @@ public function testWhereCustomStringWithBetweenEscapeFalse()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereRawSql()
+    public function testWhereRawSql(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -221,7 +221,7 @@ public function testWhereRawSql()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereValueRawSql()
+    public function testWhereValueRawSql(): void
     {
         $sql = $this->db->table('auth_bearer')
             ->select('*')
@@ -236,7 +236,7 @@ public function testWhereValueRawSql()
         $this->assertSame($expected, $sql);
     }
 
-    public function testWhereKeyOnlyRawSql()
+    public function testWhereKeyOnlyRawSql(): void
     {
         $sql = $this->db->table('auth_bearer')
             ->select('*')
@@ -251,7 +251,7 @@ public function testWhereKeyOnlyRawSql()
         $this->assertSame($expected, $sql);
     }
 
-    public function testWhereKeyAndValueRawSql()
+    public function testWhereKeyAndValueRawSql(): void
     {
         $sql = $this->db->table('auth_bearer')
             ->select('*')
@@ -266,7 +266,7 @@ public function testWhereKeyAndValueRawSql()
         $this->assertSame($expected, $sql);
     }
 
-    public function testWhereKeyAndValueRawSqlWithOperator()
+    public function testWhereKeyAndValueRawSqlWithOperator(): void
     {
         $sql = $this->db->table('auth_bearer')
             ->select('*')
@@ -281,7 +281,7 @@ public function testWhereKeyAndValueRawSqlWithOperator()
         $this->assertSame($expected, $sql);
     }
 
-    public function testWhereValueSubQuery()
+    public function testWhereValueSubQuery(): void
     {
         $expectedSQL = 'SELECT * FROM "neworder" WHERE "advance_amount" < (SELECT MAX(advance_amount) FROM "orders" WHERE "id" > 2)';
 
@@ -304,7 +304,7 @@ public function testWhereValueSubQuery()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrWhere()
+    public function testOrWhere(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -326,7 +326,7 @@ public function testOrWhere()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testOrWhereSameColumn()
+    public function testOrWhereSameColumn(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -348,7 +348,7 @@ public function testOrWhereSameColumn()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereIn()
+    public function testWhereIn(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -369,7 +369,7 @@ public function testWhereIn()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereInSubQuery()
+    public function testWhereInSubQuery(): void
     {
         $expectedSQL = 'SELECT * FROM "jobs" WHERE "id" IN (SELECT "job_id" FROM "users_jobs" WHERE "user_id" = 3)';
 
@@ -405,7 +405,7 @@ public function provideInvalidKeys(): iterable
      *
      * @param mixed $key
      */
-    public function testWhereInvalidKeyThrowInvalidArgumentException($key)
+    public function testWhereInvalidKeyThrowInvalidArgumentException($key): void
     {
         $this->expectException('InvalidArgumentException');
         $builder = $this->db->table('jobs');
@@ -427,7 +427,7 @@ public function provideInvalidValues(): iterable
      *
      * @param mixed $values
      */
-    public function testWhereInEmptyValuesThrowInvalidArgumentException($values)
+    public function testWhereInEmptyValuesThrowInvalidArgumentException($values): void
     {
         $this->expectException('InvalidArgumentException');
         $builder = $this->db->table('jobs');
@@ -435,7 +435,7 @@ public function testWhereInEmptyValuesThrowInvalidArgumentException($values)
         $builder->whereIn('name', $values);
     }
 
-    public function testWhereNotIn()
+    public function testWhereNotIn(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -456,7 +456,7 @@ public function testWhereNotIn()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testWhereNotInSubQuery()
+    public function testWhereNotInSubQuery(): void
     {
         $expectedSQL = 'SELECT * FROM "jobs" WHERE "id" NOT IN (SELECT "job_id" FROM "users_jobs" WHERE "user_id" = 3)';
 
@@ -479,7 +479,7 @@ public function testWhereNotInSubQuery()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrWhereIn()
+    public function testOrWhereIn(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -504,7 +504,7 @@ public function testOrWhereIn()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testOrWhereInSubQuery()
+    public function testOrWhereInSubQuery(): void
     {
         $expectedSQL = 'SELECT * FROM "jobs" WHERE "deleted_at" IS NULL OR "id" IN (SELECT "job_id" FROM "users_jobs" WHERE "user_id" = 3)';
 
@@ -527,7 +527,7 @@ public function testOrWhereInSubQuery()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testOrWhereNotIn()
+    public function testOrWhereNotIn(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -552,7 +552,7 @@ public function testOrWhereNotIn()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
-    public function testOrWhereNotInSubQuery()
+    public function testOrWhereNotInSubQuery(): void
     {
         $expectedSQL = 'SELECT * FROM "jobs" WHERE "deleted_at" IS NULL OR "id" NOT IN (SELECT "job_id" FROM "users_jobs" WHERE "user_id" = 3)';
 
@@ -578,7 +578,7 @@ public function testOrWhereNotInSubQuery()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4443
      */
-    public function testWhereWithLower()
+    public function testWhereWithLower(): void
     {
         $builder = $this->db->table('jobs');
         $builder->where('LOWER(jobs.name)', 'accountant');
@@ -587,7 +587,7 @@ public function testWhereWithLower()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhereValueIsString()
+    public function testWhereValueIsString(): void
     {
         $builder = $this->db->table('users');
 
@@ -599,7 +599,7 @@ public function testWhereValueIsString()
         $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
     }
 
-    public function testWhereValueIsFloat()
+    public function testWhereValueIsFloat(): void
     {
         $builder = $this->db->table('users');
 
@@ -616,7 +616,7 @@ public function testWhereValueIsFloat()
      * Other databases may not work well, so we may want to change the behavior
      * to match the specifications of the database driver.
      */
-    public function testWhereValueIsTrue()
+    public function testWhereValueIsTrue(): void
     {
         $builder = $this->db->table('users');
 
@@ -631,7 +631,7 @@ public function testWhereValueIsTrue()
      * Other databases may not work well, so we may want to change the behavior
      * to match the specifications of the database driver.
      */
-    public function testWhereValueIsFalse()
+    public function testWhereValueIsFalse(): void
     {
         $builder = $this->db->table('users');
 
@@ -644,7 +644,7 @@ public function testWhereValueIsFalse()
     /**
      * Check if SQL injection is not possible when unexpected values are passed
      */
-    public function testWhereValueIsArray()
+    public function testWhereValueIsArray(): void
     {
         $builder = $this->db->table('users');
 
@@ -660,7 +660,7 @@ public function testWhereValueIsArray()
     /**
      * Check if SQL injection is not possible when unexpected values are passed
      */
-    public function testWhereValueIsArrayOfArray()
+    public function testWhereValueIsArrayOfArray(): void
     {
         $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('Array to string conversion');
@@ -675,7 +675,7 @@ public function testWhereValueIsArrayOfArray()
     /**
      * Check if SQL injection is not possible when unexpected values are passed
      */
-    public function testWhereValueIsArrayOfObject()
+    public function testWhereValueIsArrayOfObject(): void
     {
         $this->expectException(Error::class);
         $this->expectExceptionMessage('Object of class stdClass could not be converted to string');
@@ -687,7 +687,7 @@ public function testWhereValueIsArrayOfObject()
         $builder->getCompiledSelect();
     }
 
-    public function testWhereValueIsNull()
+    public function testWhereValueIsNull(): void
     {
         $builder = $this->db->table('users');
 
@@ -700,7 +700,7 @@ public function testWhereValueIsNull()
     /**
      * Check if SQL injection is not possible when unexpected values are passed
      */
-    public function testWhereValueIsStdClass()
+    public function testWhereValueIsStdClass(): void
     {
         $this->expectException(Error::class);
         $this->expectExceptionMessage('Object of class stdClass could not be converted to string');
@@ -715,7 +715,7 @@ public function testWhereValueIsStdClass()
     /**
      * Check if SQL injection is not possible when unexpected values are passed
      */
-    public function testWhereValueIsDateTime()
+    public function testWhereValueIsDateTime(): void
     {
         $this->expectException(Error::class);
         $this->expectExceptionMessage('Object of class DateTime could not be converted to string');
diff --git a/tests/system/Database/ConfigTest.php b/tests/system/Database/ConfigTest.php
index 31d2e54a8e9c..b401d541b7a8 100644
--- a/tests/system/Database/ConfigTest.php
+++ b/tests/system/Database/ConfigTest.php
@@ -105,7 +105,7 @@ protected function tearDown(): void
         $this->setPrivateProperty(Config::class, 'instances', []);
     }
 
-    public function testConnectionGroup()
+    public function testConnectionGroup(): void
     {
         $conn = Config::connect($this->group, false);
         $this->assertInstanceOf(BaseConnection::class, $conn);
@@ -123,7 +123,7 @@ public function testConnectionGroup()
         $this->assertSame($this->group['DBCollat'], $this->getPrivateProperty($conn, 'DBCollat'));
     }
 
-    public function testConnectionGroupWithDSN()
+    public function testConnectionGroupWithDSN(): void
     {
         $conn = Config::connect($this->dsnGroup, false);
         $this->assertInstanceOf(BaseConnection::class, $conn);
@@ -143,7 +143,7 @@ public function testConnectionGroupWithDSN()
         $this->assertSame([], $this->getPrivateProperty($conn, 'failover'));
     }
 
-    public function testConnectionGroupWithDSNPostgre()
+    public function testConnectionGroupWithDSNPostgre(): void
     {
         $conn = Config::connect($this->dsnGroupPostgre, false);
         $this->assertInstanceOf(BaseConnection::class, $conn);
@@ -171,7 +171,7 @@ public function testConnectionGroupWithDSNPostgre()
         $this->assertSame($expected, $this->getPrivateProperty($conn, 'DSN'));
     }
 
-    public function testConnectionGroupWithDSNPostgreNative()
+    public function testConnectionGroupWithDSNPostgreNative(): void
     {
         $conn = Config::connect($this->dsnGroupPostgreNative, false);
         $this->assertInstanceOf(BaseConnection::class, $conn);
@@ -196,7 +196,7 @@ public function testConnectionGroupWithDSNPostgreNative()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/7550
      */
-    public function testConvertDSN(string $input, string $expected)
+    public function testConvertDSN(string $input, string $expected): void
     {
         $this->dsnGroupPostgreNative['DSN'] = $input;
         $conn                               = Config::connect($this->dsnGroupPostgreNative, false);
diff --git a/tests/system/Database/DatabaseSeederTest.php b/tests/system/Database/DatabaseSeederTest.php
index adf16b82cd02..467198348e80 100644
--- a/tests/system/Database/DatabaseSeederTest.php
+++ b/tests/system/Database/DatabaseSeederTest.php
@@ -22,7 +22,7 @@
  */
 final class DatabaseSeederTest extends CIUnitTestCase
 {
-    public function testInstantiateNoSeedPath()
+    public function testInstantiateNoSeedPath(): void
     {
         $this->expectException('InvalidArgumentException');
 
@@ -31,7 +31,7 @@ public function testInstantiateNoSeedPath()
         new Seeder($config);
     }
 
-    public function testInstantiateNotDirSeedPath()
+    public function testInstantiateNotDirSeedPath(): void
     {
         $this->expectException('InvalidArgumentException');
 
@@ -43,12 +43,12 @@ public function testInstantiateNotDirSeedPath()
     /**
      * @TODO remove this when Seeder::faker() is removed
      */
-    public function testFakerGet()
+    public function testFakerGet(): void
     {
         $this->assertInstanceOf(Generator::class, Seeder::faker());
     }
 
-    public function testCallOnEmptySeeder()
+    public function testCallOnEmptySeeder(): void
     {
         $this->expectException('InvalidArgumentException');
 
diff --git a/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce1Test.php b/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce1Test.php
index 7177c0e5da37..aa164a16954a 100644
--- a/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce1Test.php
+++ b/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce1Test.php
@@ -64,7 +64,7 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    protected function setUpAddNamespace()
+    protected function setUpAddNamespace(): void
     {
         Services::autoloader()->addNamespace(
             'Tests\Support\MigrationTestMigrations',
@@ -79,7 +79,7 @@ protected function tearDown(): void
         $this->regressDatabase();
     }
 
-    public function testMigrationDone()
+    public function testMigrationDone(): void
     {
         $this->seeInDatabase('foo', ['key' => 'foobar']);
 
@@ -88,7 +88,7 @@ public function testMigrationDone()
         $this->dropTableFoo();
     }
 
-    private function dropTableFoo()
+    private function dropTableFoo(): void
     {
         $forge = Database::forge();
         $forge->dropTable('foo', true);
diff --git a/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce2Test.php b/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce2Test.php
index 6c8f2f4e3504..dc24b373912d 100644
--- a/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce2Test.php
+++ b/tests/system/Database/DatabaseTestCase/DatabaseTestCaseMigrationOnce2Test.php
@@ -64,7 +64,7 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    protected function setUpAddNamespace()
+    protected function setUpAddNamespace(): void
     {
         Services::autoloader()->addNamespace(
             'Tests\Support\MigrationTestMigrations',
@@ -79,7 +79,7 @@ protected function tearDown(): void
         $this->regressDatabase();
     }
 
-    public function testMigrationDone()
+    public function testMigrationDone(): void
     {
         $this->seeInDatabase('foo', ['key' => 'foobar']);
     }
diff --git a/tests/system/Database/DatabaseTestCaseTest.php b/tests/system/Database/DatabaseTestCaseTest.php
index 0a1c164b3066..336c45a53341 100644
--- a/tests/system/Database/DatabaseTestCaseTest.php
+++ b/tests/system/Database/DatabaseTestCaseTest.php
@@ -69,7 +69,7 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    protected function setUpAddNamespace()
+    protected function setUpAddNamespace(): void
     {
         Services::autoloader()->addNamespace(
             'Tests\Support\MigrationTestMigrations',
@@ -84,12 +84,12 @@ protected function tearDown(): void
         $this->regressDatabase();
     }
 
-    public function testMultipleSeeders()
+    public function testMultipleSeeders(): void
     {
         $this->seeInDatabase('user', ['name' => 'Jerome Lohan']);
     }
 
-    public function testMultipleMigrationNamespaces()
+    public function testMultipleMigrationNamespaces(): void
     {
         $this->seeInDatabase('foo', ['key' => 'foobar']);
     }
diff --git a/tests/system/Database/Forge/CreateTableTest.php b/tests/system/Database/Forge/CreateTableTest.php
index f982358b5f69..2d50ac9858e5 100644
--- a/tests/system/Database/Forge/CreateTableTest.php
+++ b/tests/system/Database/Forge/CreateTableTest.php
@@ -23,7 +23,7 @@
  */
 final class CreateTableTest extends CIUnitTestCase
 {
-    public function testCreateTableWithDefaultRawSql()
+    public function testCreateTableWithDefaultRawSql(): void
     {
         $sql = <<<'SQL'
             CREATE TABLE "foo" (
diff --git a/tests/system/Database/Forge/DropForeignKeyTest.php b/tests/system/Database/Forge/DropForeignKeyTest.php
index c65eed7ac10c..d90ae4d9c519 100644
--- a/tests/system/Database/Forge/DropForeignKeyTest.php
+++ b/tests/system/Database/Forge/DropForeignKeyTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->db = new MockConnection([]);
     }
 
-    public function testDropForeignKeyWithEmptyDropConstraintStrProperty()
+    public function testDropForeignKeyWithEmptyDropConstraintStrProperty(): void
     {
         $this->setPrivateProperty($this->db, 'DBDebug', true);
 
diff --git a/tests/system/Database/Live/AliasTest.php b/tests/system/Database/Live/AliasTest.php
index 6cb993431daf..93a0bd29a661 100644
--- a/tests/system/Database/Live/AliasTest.php
+++ b/tests/system/Database/Live/AliasTest.php
@@ -27,7 +27,7 @@ final class AliasTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testAlias()
+    public function testAlias(): void
     {
         $builder = $this->db->table('job j');
 
diff --git a/tests/system/Database/Live/BadQueryTest.php b/tests/system/Database/Live/BadQueryTest.php
index 6ae58b182ad2..a85ba2f793be 100644
--- a/tests/system/Database/Live/BadQueryTest.php
+++ b/tests/system/Database/Live/BadQueryTest.php
@@ -28,7 +28,7 @@ final class BadQueryTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testBadQueryDebugTrue()
+    public function testBadQueryDebugTrue(): void
     {
         $this->enableDBDebug();
 
@@ -39,7 +39,7 @@ public function testBadQueryDebugTrue()
         // this code is never executed
     }
 
-    public function testBadQueryDebugFalse()
+    public function testBadQueryDebugFalse(): void
     {
         // WARNING this value will persist! take care to roll it back.
         $this->disableDBDebug();
diff --git a/tests/system/Database/Live/ConnectTest.php b/tests/system/Database/Live/ConnectTest.php
index f618ee465136..52322fa3ed01 100644
--- a/tests/system/Database/Live/ConnectTest.php
+++ b/tests/system/Database/Live/ConnectTest.php
@@ -44,7 +44,7 @@ protected function setUp(): void
         $this->group2['DBDriver'] = 'Postgre';
     }
 
-    public function testConnectWithMultipleCustomGroups()
+    public function testConnectWithMultipleCustomGroups(): void
     {
         // We should have our test database connection already.
         $instances = $this->getPrivateProperty(Database::class, 'instances');
@@ -59,7 +59,7 @@ public function testConnectWithMultipleCustomGroups()
         $this->assertCount(3, $instances);
     }
 
-    public function testConnectReturnsProvidedConnection()
+    public function testConnectReturnsProvidedConnection(): void
     {
         $config = config('Database');
 
@@ -76,7 +76,7 @@ public function testConnectReturnsProvidedConnection()
         $this->assertSame($db1, $db2);
     }
 
-    public function testConnectWorksWithGroupName()
+    public function testConnectWorksWithGroupName(): void
     {
         $config = config('Database');
 
@@ -92,7 +92,7 @@ public function testConnectWorksWithGroupName()
         $this->assertSame('MySQLi', $this->getPrivateProperty($db1, 'DBDriver'));
     }
 
-    public function testConnectWithFailover()
+    public function testConnectWithFailover(): void
     {
         $this->tests['failover'][] = $this->tests;
         unset($this->tests['failover'][0]['failover']);
diff --git a/tests/system/Database/Live/CountTest.php b/tests/system/Database/Live/CountTest.php
index a84170e3d463..28e74fdc1163 100644
--- a/tests/system/Database/Live/CountTest.php
+++ b/tests/system/Database/Live/CountTest.php
@@ -27,27 +27,27 @@ final class CountTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testCountReturnsZeroWithNoResults()
+    public function testCountReturnsZeroWithNoResults(): void
     {
         $this->assertSame(0, $this->db->table('empty')->countAll());
     }
 
-    public function testCountAllReturnsCorrectInteger()
+    public function testCountAllReturnsCorrectInteger(): void
     {
         $this->assertSame(4, $this->db->table('job')->countAll());
     }
 
-    public function testCountAllResultsReturnsZeroWithNoResults()
+    public function testCountAllResultsReturnsZeroWithNoResults(): void
     {
         $this->assertSame(0, $this->db->table('job')->where('name', 'Superstar')->countAllResults());
     }
 
-    public function testCountAllResultsReturnsCorrectValue()
+    public function testCountAllResultsReturnsCorrectValue(): void
     {
         $this->assertSame(1, $this->db->table('job')->where('name', 'Developer')->countAllResults());
     }
 
-    public function testCountAllResultsHonorsReset()
+    public function testCountAllResultsHonorsReset(): void
     {
         $builder = $this->db->table('job');
 
diff --git a/tests/system/Database/Live/DatabaseTestTraitCaseTest.php b/tests/system/Database/Live/DatabaseTestTraitCaseTest.php
index 0558905ca061..e514e5b57bb0 100644
--- a/tests/system/Database/Live/DatabaseTestTraitCaseTest.php
+++ b/tests/system/Database/Live/DatabaseTestTraitCaseTest.php
@@ -27,31 +27,31 @@ final class DatabaseTestTraitCaseTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testHasInDatabase()
+    public function testHasInDatabase(): void
     {
         $this->hasInDatabase('user', ['name' => 'Ricky', 'email' => 'sofine@example.com', 'country' => 'US']);
 
         $this->seeInDatabase('user', ['name' => 'Ricky', 'email' => 'sofine@example.com', 'country' => 'US']);
     }
 
-    public function testDontSeeInDatabase()
+    public function testDontSeeInDatabase(): void
     {
         $this->dontSeeInDatabase('user', ['name' => 'Ricardo']);
     }
 
-    public function testSeeNumRecords()
+    public function testSeeNumRecords(): void
     {
         $this->seeNumRecords(2, 'user', ['country' => 'US']);
     }
 
-    public function testGrabFromDatabase()
+    public function testGrabFromDatabase(): void
     {
         $email = $this->grabFromDatabase('user', 'email', ['name' => 'Derek Jones']);
 
         $this->assertSame('derek@world.com', $email);
     }
 
-    public function testSeeInDatabase()
+    public function testSeeInDatabase(): void
     {
         $this->hasInDatabase('user', [
             'name'    => 'Ricardo',
diff --git a/tests/system/Database/Live/DbDebugTest.php b/tests/system/Database/Live/DbDebugTest.php
index 3f781cad4979..6209450ecbb6 100644
--- a/tests/system/Database/Live/DbDebugTest.php
+++ b/tests/system/Database/Live/DbDebugTest.php
@@ -26,7 +26,7 @@ final class DbDebugTest extends CIUnitTestCase
 
     protected $refresh = true;
 
-    public function testDBDebugTrue()
+    public function testDBDebugTrue(): void
     {
         $this->enableDBDebug();
 
@@ -35,7 +35,7 @@ public function testDBDebugTrue()
         $this->db->simpleQuery('SELECT * FROM db_error');
     }
 
-    public function testDBDebugFalse()
+    public function testDBDebugFalse(): void
     {
         // WARNING this value will persist! take care to roll it back.
         $this->disableDBDebug();
diff --git a/tests/system/Database/Live/DbUtilsTest.php b/tests/system/Database/Live/DbUtilsTest.php
index 1b4697703d8d..cbb1fd8f1ae2 100644
--- a/tests/system/Database/Live/DbUtilsTest.php
+++ b/tests/system/Database/Live/DbUtilsTest.php
@@ -29,7 +29,7 @@ final class DbUtilsTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testUtilsBackup()
+    public function testUtilsBackup(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -39,7 +39,7 @@ public function testUtilsBackup()
         $util->backup();
     }
 
-    public function testUtilsBackupWithParamsArray()
+    public function testUtilsBackupWithParamsArray(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -52,7 +52,7 @@ public function testUtilsBackupWithParamsArray()
         $util->backup($params);
     }
 
-    public function testUtilsBackupWithParamsString()
+    public function testUtilsBackupWithParamsString(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -62,7 +62,7 @@ public function testUtilsBackupWithParamsString()
         $util->backup('db_jobs');
     }
 
-    public function testUtilsListDatabases()
+    public function testUtilsListDatabases(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -78,7 +78,7 @@ public function testUtilsListDatabases()
         }
     }
 
-    public function testUtilsDatabaseExist()
+    public function testUtilsDatabaseExist(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -94,7 +94,7 @@ public function testUtilsDatabaseExist()
         }
     }
 
-    public function testUtilsOptimizeDatabase()
+    public function testUtilsOptimizeDatabase(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -109,7 +109,7 @@ public function testUtilsOptimizeDatabase()
         $this->assertTrue((bool) $d);
     }
 
-    public function testUtilsOptimizeTableFalseOptimizeDatabaseDebugTrue()
+    public function testUtilsOptimizeTableFalseOptimizeDatabaseDebugTrue(): void
     {
         $util = (new Database())->loadUtils($this->db);
         $this->setPrivateProperty($util, 'optimizeTable', false);
@@ -124,7 +124,7 @@ public function testUtilsOptimizeTableFalseOptimizeDatabaseDebugTrue()
         // this point in code execution will never be reached
     }
 
-    public function testUtilsOptimizeTableFalseOptimizeDatabaseDebugFalse()
+    public function testUtilsOptimizeTableFalseOptimizeDatabaseDebugFalse(): void
     {
         $util = (new Database())->loadUtils($this->db);
         $this->setPrivateProperty($util, 'optimizeTable', false);
@@ -138,7 +138,7 @@ public function testUtilsOptimizeTableFalseOptimizeDatabaseDebugFalse()
         $this->enableDBDebug();
     }
 
-    public function testUtilsOptimizeTable()
+    public function testUtilsOptimizeTable(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -153,7 +153,7 @@ public function testUtilsOptimizeTable()
         $this->assertTrue($d);
     }
 
-    public function testUtilsOptimizeTableFalseOptimizeTable()
+    public function testUtilsOptimizeTableFalseOptimizeTable(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -165,7 +165,7 @@ public function testUtilsOptimizeTableFalseOptimizeTable()
         $util->optimizeTable('db_job');
     }
 
-    public function testUtilsRepairTable()
+    public function testUtilsRepairTable(): void
     {
         $util = (new Database())->loadUtils($this->db);
 
@@ -175,7 +175,7 @@ public function testUtilsRepairTable()
         $util->repairTable('db_job');
     }
 
-    public function testUtilsCSVFromResult()
+    public function testUtilsCSVFromResult(): void
     {
         $data = $this->db->table('job')->get();
 
@@ -188,7 +188,7 @@ public function testUtilsCSVFromResult()
         $this->assertSame('"1","Developer","Awesome job, but sometimes makes you bored","","",""', $data[1]);
     }
 
-    public function testUtilsXMLFromResult()
+    public function testUtilsXMLFromResult(): void
     {
         $data = $this->db->table('job')->where('id', 4)->get();
 
diff --git a/tests/system/Database/Live/DeleteTest.php b/tests/system/Database/Live/DeleteTest.php
index 645e4a1de3b3..4383d32b78a0 100644
--- a/tests/system/Database/Live/DeleteTest.php
+++ b/tests/system/Database/Live/DeleteTest.php
@@ -35,14 +35,14 @@ final class DeleteTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testDeleteThrowExceptionWithNoCriteria()
+    public function testDeleteThrowExceptionWithNoCriteria(): void
     {
         $this->expectException(DatabaseException::class);
 
         $this->db->table('job')->delete();
     }
 
-    public function testDeleteWithExternalWhere()
+    public function testDeleteWithExternalWhere(): void
     {
         $this->seeInDatabase('job', ['name' => 'Developer']);
 
@@ -51,7 +51,7 @@ public function testDeleteWithExternalWhere()
         $this->dontSeeInDatabase('job', ['name' => 'Developer']);
     }
 
-    public function testDeleteWithInternalWhere()
+    public function testDeleteWithInternalWhere(): void
     {
         $this->seeInDatabase('job', ['name' => 'Developer']);
 
@@ -60,7 +60,7 @@ public function testDeleteWithInternalWhere()
         $this->dontSeeInDatabase('job', ['name' => 'Developer']);
     }
 
-    public function testDeleteWithLimit()
+    public function testDeleteWithLimit(): void
     {
         $this->seeNumRecords(2, 'user', ['country' => 'US']);
 
@@ -75,7 +75,7 @@ public function testDeleteWithLimit()
         $this->seeNumRecords(1, 'user', ['country' => 'US']);
     }
 
-    public function testDeleteBatch()
+    public function testDeleteBatch(): void
     {
         $data = [
             ['userid' => 1, 'username' => 'Derek J', 'unused' => 'You can have fields you dont use'],
@@ -98,7 +98,7 @@ public function testDeleteBatch()
         $this->dontSeeInDatabase('user', ['email' => 'ahmadinejad@world.com', 'name' => 'Ahmadinejad']);
     }
 
-    public function testDeleteBatchWithQuery()
+    public function testDeleteBatchWithQuery(): void
     {
         $this->forge = Database::forge($this->DBGroup);
 
diff --git a/tests/system/Database/Live/EmptyTest.php b/tests/system/Database/Live/EmptyTest.php
index ac0de48a1d5e..72246df26915 100644
--- a/tests/system/Database/Live/EmptyTest.php
+++ b/tests/system/Database/Live/EmptyTest.php
@@ -27,14 +27,14 @@ final class EmptyTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testEmpty()
+    public function testEmpty(): void
     {
         $this->db->table('misc')->emptyTable();
 
         $this->assertSame(0, $this->db->table('misc')->countAll());
     }
 
-    public function testTruncate()
+    public function testTruncate(): void
     {
         $this->db->table('misc')->truncate();
 
diff --git a/tests/system/Database/Live/EscapeTest.php b/tests/system/Database/Live/EscapeTest.php
index d0eb6babf450..32a383a0fc2b 100644
--- a/tests/system/Database/Live/EscapeTest.php
+++ b/tests/system/Database/Live/EscapeTest.php
@@ -39,12 +39,12 @@ protected function setUp(): void
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/606
      */
-    public function testDoesNotEscapeNegativeNumbers()
+    public function testDoesNotEscapeNegativeNumbers(): void
     {
         $this->assertSame(-100, $this->db->escape(-100));
     }
 
-    public function testEscape()
+    public function testEscape(): void
     {
         $expected = "SELECT * FROM brands WHERE name = 'O" . $this->char . "'Doules'";
         $sql      = 'SELECT * FROM brands WHERE name = ' . $this->db->escape("O'Doules");
@@ -52,7 +52,7 @@ public function testEscape()
         $this->assertSame($expected, $sql);
     }
 
-    public function testEscapeString()
+    public function testEscapeString(): void
     {
         $expected = "SELECT * FROM brands WHERE name = 'O" . $this->char . "'Doules'";
         $sql      = "SELECT * FROM brands WHERE name = '" . $this->db->escapeString("O'Doules") . "'";
@@ -60,7 +60,7 @@ public function testEscapeString()
         $this->assertSame($expected, $sql);
     }
 
-    public function testEscapeLikeString()
+    public function testEscapeLikeString(): void
     {
         $expected = "SELECT * FROM brands WHERE column LIKE '%10!% more%' ESCAPE '!'";
         $sql      = "SELECT * FROM brands WHERE column LIKE '%" . $this->db->escapeLikeString('10% more') . "%' ESCAPE '!'";
@@ -68,7 +68,7 @@ public function testEscapeLikeString()
         $this->assertSame($expected, $sql);
     }
 
-    public function testEscapeLikeStringDirect()
+    public function testEscapeLikeStringDirect(): void
     {
         if ($this->db->DBDriver === 'MySQLi') {
             $expected = "SHOW COLUMNS FROM brands WHERE column LIKE 'wild\\_chars%'";
@@ -80,7 +80,7 @@ public function testEscapeLikeStringDirect()
         }
     }
 
-    public function testEscapeStringArray()
+    public function testEscapeStringArray(): void
     {
         $stringArray = [' A simple string ', new RawSql('CURRENT_TIMESTAMP()'), false, null];
 
diff --git a/tests/system/Database/Live/FabricatorLiveTest.php b/tests/system/Database/Live/FabricatorLiveTest.php
index 761de0a39fae..15622166a606 100644
--- a/tests/system/Database/Live/FabricatorLiveTest.php
+++ b/tests/system/Database/Live/FabricatorLiveTest.php
@@ -29,7 +29,7 @@ final class FabricatorLiveTest extends CIUnitTestCase
 
     protected $refresh = true;
 
-    public function testCreateAddsToDatabase()
+    public function testCreateAddsToDatabase(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -41,7 +41,7 @@ public function testCreateAddsToDatabase()
         $this->seeInDatabase('user', ['name' => $result->name]);
     }
 
-    public function testCreateAddsCountToDatabase()
+    public function testCreateAddsCountToDatabase(): void
     {
         $count = 10;
 
@@ -55,7 +55,7 @@ public function testCreateAddsCountToDatabase()
         $this->seeNumRecords($count, 'user', []);
     }
 
-    public function testHelperCreates()
+    public function testHelperCreates(): void
     {
         helper('test');
 
@@ -64,7 +64,7 @@ public function testHelperCreates()
         $this->seeInDatabase('user', ['name' => $result->name]);
     }
 
-    public function testCreateIncrementsCount()
+    public function testCreateIncrementsCount(): void
     {
         $fabricator = new Fabricator(UserModel::class);
         $fabricator->setOverrides(['country' => 'China']);
@@ -76,7 +76,7 @@ public function testCreateIncrementsCount()
         $this->assertSame($count + 1, Fabricator::getCount('user'));
     }
 
-    public function testHelperIncrementsCount()
+    public function testHelperIncrementsCount(): void
     {
         $count = Fabricator::getCount('user');
 
@@ -85,7 +85,7 @@ public function testHelperIncrementsCount()
         $this->assertSame($count + 1, Fabricator::getCount('user'));
     }
 
-    public function testCreateThrowsOnFailure()
+    public function testCreateThrowsOnFailure(): void
     {
         $this->expectException(FrameworkException::class);
         $this->expectExceptionMessage(lang('Fabricator.createFailed', ['job', 'Too short, man!']));
@@ -93,7 +93,7 @@ public function testCreateThrowsOnFailure()
         fake(ValidModel::class, ['name' => 'eh']);
     }
 
-    public function testHelperDoesNotPersist()
+    public function testHelperDoesNotPersist(): void
     {
         helper('test');
         $result = fake(UserModel::class, ['name' => 'Derek'], false);
diff --git a/tests/system/Database/Live/ForgeTest.php b/tests/system/Database/Live/ForgeTest.php
index 90b42aec7de8..a1138c99c860 100644
--- a/tests/system/Database/Live/ForgeTest.php
+++ b/tests/system/Database/Live/ForgeTest.php
@@ -47,7 +47,7 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    public function testCreateDatabase()
+    public function testCreateDatabase(): void
     {
         if ($this->db->DBDriver === 'OCI8') {
             $this->markTestSkipped('OCI8 does not support create database.');
@@ -57,7 +57,7 @@ public function testCreateDatabase()
         $this->assertTrue($databaseCreated);
     }
 
-    public function testCreateDatabaseIfNotExists()
+    public function testCreateDatabaseIfNotExists(): void
     {
         if ($this->db->DBDriver === 'OCI8') {
             $this->markTestSkipped('OCI8 does not support create database.');
@@ -72,7 +72,7 @@ public function testCreateDatabaseIfNotExists()
         $this->assertTrue($databaseCreateIfNotExists);
     }
 
-    public function testCreateDatabaseIfNotExistsWithDb()
+    public function testCreateDatabaseIfNotExistsWithDb(): void
     {
         if ($this->db->DBDriver === 'OCI8') {
             $this->markTestSkipped('OCI8 does not support create database.');
@@ -88,7 +88,7 @@ public function testCreateDatabaseIfNotExistsWithDb()
         $this->assertTrue($databaseExists);
     }
 
-    public function testDropDatabase()
+    public function testDropDatabase(): void
     {
         if ($this->db->DBDriver === 'OCI8') {
             $this->markTestSkipped('OCI8 does not support drop database.');
@@ -102,7 +102,7 @@ public function testDropDatabase()
         $this->assertTrue($databaseDropped);
     }
 
-    public function testCreateDatabaseExceptionNoCreateStatement()
+    public function testCreateDatabaseExceptionNoCreateStatement(): void
     {
         $this->setPrivateProperty($this->forge, 'createDatabaseStr', false);
 
@@ -117,7 +117,7 @@ public function testCreateDatabaseExceptionNoCreateStatement()
         }
     }
 
-    public function testDropDatabaseExceptionNoDropStatement()
+    public function testDropDatabaseExceptionNoDropStatement(): void
     {
         $this->setPrivateProperty($this->forge, 'dropDatabaseStr', false);
 
@@ -131,7 +131,7 @@ public function testDropDatabaseExceptionNoDropStatement()
         }
     }
 
-    public function testCreateTable()
+    public function testCreateTable(): void
     {
         $this->forge->dropTable('forge_test_table', true);
 
@@ -164,7 +164,7 @@ public function testCreateTable()
         $this->forge->dropTable('forge_test_table', true);
     }
 
-    public function testCreateTableWithExists()
+    public function testCreateTableWithExists(): void
     {
         // create table so that it exists in database
         $this->forge->addField([
@@ -213,7 +213,7 @@ public function testCreateTableWithExists()
         $this->forge->dropTable('test_exists');
     }
 
-    public function testCreateTableApplyBigInt()
+    public function testCreateTableApplyBigInt(): void
     {
         $this->forge->dropTable('forge_test_table', true);
 
@@ -244,7 +244,7 @@ public function testCreateTableApplyBigInt()
         $this->forge->dropTable('forge_test_table', true);
     }
 
-    public function testCreateTableWithAttributes()
+    public function testCreateTableWithAttributes(): void
     {
         if ($this->db->DBDriver === 'OCI8') {
             $this->markTestSkipped('OCI8 does not support comments on tables or columns.');
@@ -269,7 +269,7 @@ public function testCreateTableWithAttributes()
         $this->assertTrue($exist);
     }
 
-    public function testCreateTableWithArrayFieldConstraints()
+    public function testCreateTableWithArrayFieldConstraints(): void
     {
         if (in_array($this->db->DBDriver, ['MySQLi', 'SQLite3'], true)) {
             $this->forge->dropTable('forge_array_constraint', true);
@@ -333,7 +333,7 @@ public function testCreateTableWithNullableFieldsGivesNullDataType(): void
         }
     }
 
-    public function testCreateTableWithStringField()
+    public function testCreateTableWithStringField(): void
     {
         $this->forge->dropTable('forge_test_table', true);
 
@@ -348,7 +348,7 @@ public function testCreateTableWithStringField()
         $this->assertTrue($exist);
     }
 
-    public function testCreateTableWithEmptyName()
+    public function testCreateTableWithEmptyName(): void
     {
         $this->forge->dropTable('forge_test_table', true);
 
@@ -361,7 +361,7 @@ public function testCreateTableWithEmptyName()
         $this->forge->createTable('');
     }
 
-    public function testCreateTableWithNoFields()
+    public function testCreateTableWithNoFields(): void
     {
         $this->forge->dropTable('forge_test_table', true);
 
@@ -371,7 +371,7 @@ public function testCreateTableWithNoFields()
         $this->forge->createTable('forge_test_table');
     }
 
-    public function testCreateTableWithStringFieldException()
+    public function testCreateTableWithStringFieldException(): void
     {
         $this->expectException('InvalidArgumentException');
         $this->expectExceptionMessage('Field information is required for that operation.');
@@ -384,7 +384,7 @@ public function testCreateTableWithStringFieldException()
         $this->forge->createTable('forge_test_table');
     }
 
-    public function testRenameTable()
+    public function testRenameTable(): void
     {
         $this->forge->dropTable('forge_test_table_dummy', true);
 
@@ -400,7 +400,7 @@ public function testRenameTable()
         $this->assertTrue($exist);
     }
 
-    public function testRenameTableEmptyNameException()
+    public function testRenameTableEmptyNameException(): void
     {
         $this->forge->dropTable('forge_test_table_dummy', true);
 
@@ -415,7 +415,7 @@ public function testRenameTableEmptyNameException()
         $this->forge->renameTable('forge_test_table', '');
     }
 
-    public function testRenameTableNoRenameStatementException()
+    public function testRenameTableNoRenameStatementException(): void
     {
         $this->setPrivateProperty($this->forge, 'renameTableStr', false);
 
@@ -432,7 +432,7 @@ public function testRenameTableNoRenameStatementException()
         $this->forge->renameTable('forge_test_table', 'forge_test_table_dummy');
     }
 
-    public function testDropTableWithEmptyName()
+    public function testDropTableWithEmptyName(): void
     {
         $this->expectException(DatabaseException::class);
         $this->expectExceptionMessage('A table name is required for that operation.');
@@ -440,7 +440,7 @@ public function testDropTableWithEmptyName()
         $this->forge->dropTable('', true);
     }
 
-    public function testForeignKey()
+    public function testForeignKey(): void
     {
         $this->forge->dropTable('forge_test_invoices', true);
         $this->forge->dropTable('forge_test_users', true);
@@ -505,7 +505,7 @@ public function testForeignKey()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4986
      */
-    public function testForeignKeyAddingWithStringFields()
+    public function testForeignKeyAddingWithStringFields(): void
     {
         if ($this->db->DBDriver !== 'MySQLi') {
             $this->markTestSkipped('Testing only on MySQLi but fix expands to all DBs.');
@@ -544,7 +544,7 @@ public function testForeignKeyAddingWithStringFields()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4310
      */
-    public function testCompositeForeignKey()
+    public function testCompositeForeignKey(): void
     {
         $this->forge->dropTable('forge_test_invoices', true);
         $this->forge->dropTable('forge_test_users', true);
@@ -620,7 +620,7 @@ public function testCompositeForeignKey()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4310
      */
-    public function testCompositeForeignKeyFieldNotExistException()
+    public function testCompositeForeignKeyFieldNotExistException(): void
     {
         $this->expectException(DatabaseException::class);
         if ($this->db->DBDriver === 'SQLite3') {
@@ -679,7 +679,7 @@ public function testCompositeForeignKeyFieldNotExistException()
         $this->forge->createTable('forge_test_invoices', true, $attributes);
     }
 
-    public function testForeignKeyFieldNotExistException()
+    public function testForeignKeyFieldNotExistException(): void
     {
         $this->expectException(DatabaseException::class);
         if ($this->db->DBDriver === 'SQLite3') {
@@ -730,7 +730,7 @@ public function testForeignKeyFieldNotExistException()
         $this->forge->createTable('forge_test_invoices', true, $attributes);
     }
 
-    public function testDropForeignKey()
+    public function testDropForeignKey(): void
     {
         $this->forge->dropTable('forge_test_invoices', true);
         $this->forge->dropTable('forge_test_users', true);
@@ -792,7 +792,7 @@ public function testDropForeignKey()
         $this->forge->dropTable('forge_test_users', true);
     }
 
-    public function testAddColumn()
+    public function testAddColumn(): void
     {
         $this->forge->dropTable('forge_test_table', true);
 
@@ -827,7 +827,7 @@ public function testAddColumn()
         $this->assertSame('username', $fieldNames[1]);
     }
 
-    public function testAddFields()
+    public function testAddFields(): void
     {
         $tableName = 'forge_test_fields';
         if ($this->db->DBDriver === 'OCI8') {
@@ -1047,7 +1047,7 @@ public function testAddFields()
         $this->assertSame($expected, json_decode(json_encode($fieldsData), true));
     }
 
-    public function testCompositeKey()
+    public function testCompositeKey(): void
     {
         $this->forge->dropTable('forge_test_1', true);
 
@@ -1142,7 +1142,7 @@ public function testCompositeKey()
         $this->forge->dropTable('forge_test_1', true);
     }
 
-    public function testSetKeyNames()
+    public function testSetKeyNames(): void
     {
         $this->forge->dropTable('forge_test_1', true);
 
@@ -1206,7 +1206,7 @@ public function testSetKeyNames()
         $this->forge->dropTable('forge_test_1', true);
     }
 
-    public function testDropColumn()
+    public function testDropColumn(): void
     {
         $this->forge->dropTable('forge_test_two', true);
 
@@ -1238,7 +1238,7 @@ public function testDropColumn()
         $this->forge->dropTable('forge_test_two', true);
     }
 
-    public function testModifyColumnRename()
+    public function testModifyColumnRename(): void
     {
         $this->forge->dropTable('forge_test_three', true);
 
@@ -1278,7 +1278,7 @@ public function testModifyColumnRename()
         $this->forge->dropTable('forge_test_three', true);
     }
 
-    public function testModifyColumnNullTrue()
+    public function testModifyColumnNullTrue(): void
     {
         // @TODO remove this in `4.4` branch
         if ($this->db->DBDriver === 'SQLSRV') {
@@ -1312,7 +1312,7 @@ public function testModifyColumnNullTrue()
         $this->forge->dropTable('forge_test_modify', true);
     }
 
-    public function testModifyColumnNullFalse()
+    public function testModifyColumnNullFalse(): void
     {
         // @TODO remove this in `4.4` branch
         if ($this->db->DBDriver === 'SQLSRV') {
@@ -1363,7 +1363,7 @@ private function getMetaData(string $column, string $table): stdClass
         return $fields[$name];
     }
 
-    public function testConnectWithArrayGroup()
+    public function testConnectWithArrayGroup(): void
     {
         $group = config('Database');
         $group = $group->tests;
@@ -1376,7 +1376,7 @@ public function testConnectWithArrayGroup()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1983
      */
-    public function testDropTableSuccess()
+    public function testDropTableSuccess(): void
     {
         // Add an index to user table so we have
         // something to work with
@@ -1400,7 +1400,7 @@ public function testDropTableSuccess()
         }
     }
 
-    public function testDropMultipleColumnWithArray()
+    public function testDropMultipleColumnWithArray(): void
     {
         $this->forge->dropTable('forge_test_two', true);
 
@@ -1438,7 +1438,7 @@ public function testDropMultipleColumnWithArray()
         $this->forge->dropTable('forge_test_two', true);
     }
 
-    public function testDropMultipleColumnWithString()
+    public function testDropMultipleColumnWithString(): void
     {
         $this->forge->dropTable('forge_test_four', true);
 
@@ -1476,7 +1476,7 @@ public function testDropMultipleColumnWithString()
         $this->forge->dropTable('forge_test_four', true);
     }
 
-    public function testDropKey()
+    public function testDropKey(): void
     {
         $this->forge->dropTable('key_test_users', true);
         $keyName = 'key_test_users_id';
@@ -1510,7 +1510,7 @@ public function testDropKey()
         $this->forge->dropTable('key_test_users', true);
     }
 
-    public function testAddTextColumnWithConstraint()
+    public function testAddTextColumnWithConstraint(): void
     {
         // some DBMS do not allow a constraint for type TEXT
         $this->forge->addColumn('user', [
@@ -1527,7 +1527,7 @@ public function testAddTextColumnWithConstraint()
         $this->assertFalse($this->db->fieldExists('text_with_constraint', 'user'));
     }
 
-    public function testDropPrimaryKey()
+    public function testDropPrimaryKey(): void
     {
         $this->forge->dropTable('forge_test_users', true);
 
@@ -1563,7 +1563,7 @@ public function testDropPrimaryKey()
         $this->forge->dropTable('forge_test_users', true);
     }
 
-    public function testProcessIndexes()
+    public function testProcessIndexes(): void
     {
         // make sure tables don't exist
         $this->forge->dropTable('actions', true);
@@ -1627,7 +1627,7 @@ public function testProcessIndexes()
         $this->forge->dropTable('user2', true);
     }
 
-    private function createUser2TableWithKeys()
+    private function createUser2TableWithKeys(): void
     {
         $fields = [
             'id'         => ['type' => 'INTEGER', 'constraint' => 3, 'auto_increment' => true],
@@ -1645,7 +1645,7 @@ private function createUser2TableWithKeys()
             ->createTable('user2', true);
     }
 
-    private function populateUser2Table()
+    private function populateUser2Table(): void
     {
         $data = [
             [
@@ -1672,7 +1672,7 @@ private function populateUser2Table()
         $this->db->table('user2')->insertBatch($data);
     }
 
-    private function createActionsTable()
+    private function createActionsTable(): void
     {
         $fields = [
             'id'       => ['type' => 'int', 'constraint' => 9],
@@ -1685,7 +1685,7 @@ private function createActionsTable()
         $this->forge->createTable('actions');
     }
 
-    private function insertDataTest()
+    private function insertDataTest(): void
     {
         $data = [
             [
diff --git a/tests/system/Database/Live/FromTest.php b/tests/system/Database/Live/FromTest.php
index a3688ae03616..63627c18fab8 100644
--- a/tests/system/Database/Live/FromTest.php
+++ b/tests/system/Database/Live/FromTest.php
@@ -27,21 +27,21 @@ final class FromTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testFromCanAddTables()
+    public function testFromCanAddTables(): void
     {
         $result = $this->db->table('job')->from('misc')->get()->getResult();
 
         $this->assertCount(12, $result);
     }
 
-    public function testFromCanOverride()
+    public function testFromCanOverride(): void
     {
         $result = $this->db->table('job')->from('misc', true)->get()->getResult();
 
         $this->assertCount(3, $result);
     }
 
-    public function testFromWithWhere()
+    public function testFromWithWhere(): void
     {
         $result = $this->db->table('job')->from('user')->where('user.id', 1)->get()->getResult();
 
diff --git a/tests/system/Database/Live/GetNumRowsTest.php b/tests/system/Database/Live/GetNumRowsTest.php
index ff9c3e3a6fe9..9f45ae5274b2 100644
--- a/tests/system/Database/Live/GetNumRowsTest.php
+++ b/tests/system/Database/Live/GetNumRowsTest.php
@@ -52,7 +52,7 @@ protected function tearDown(): void
     /**
      * tests newly added ResultInterface::getNumRows with a live db
      */
-    public function testGetRowNum()
+    public function testGetRowNum(): void
     {
         $query = $this->db->table('job')->get();
         $this->assertSame(4, $query->getNumRows());
diff --git a/tests/system/Database/Live/GetTest.php b/tests/system/Database/Live/GetTest.php
index 29dbdad10c0d..7ee169d55843 100644
--- a/tests/system/Database/Live/GetTest.php
+++ b/tests/system/Database/Live/GetTest.php
@@ -28,7 +28,7 @@ final class GetTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testGet()
+    public function testGet(): void
     {
         $jobs = $this->db->table('job')->get()->getResult();
 
@@ -39,7 +39,7 @@ public function testGet()
         $this->assertSame('Musician', $jobs[3]->name);
     }
 
-    public function testGetWitLimit()
+    public function testGetWitLimit(): void
     {
         $jobs = $this->db->table('job')->get(2, 2)->getResult();
 
@@ -48,7 +48,7 @@ public function testGetWitLimit()
         $this->assertSame('Musician', $jobs[1]->name);
     }
 
-    public function testGetWhereArray()
+    public function testGetWhereArray(): void
     {
         $jobs = $this->db->table('job')
             ->getWhere(['id' => 1])
@@ -58,7 +58,7 @@ public function testGetWhereArray()
         $this->assertSame('Developer', $jobs[0]->name);
     }
 
-    public function testGetWhereWithLimits()
+    public function testGetWhereWithLimits(): void
     {
         $jobs = $this->db->table('job')
             ->getWhere('id > 1', 1, 1)
@@ -68,14 +68,14 @@ public function testGetWhereWithLimits()
         $this->assertSame('Accountant', $jobs[0]->name);
     }
 
-    public function testGetFieldCount()
+    public function testGetFieldCount(): void
     {
         $jobs = $this->db->table('job')->get()->getFieldCount();
 
         $this->assertSame(6, $jobs);
     }
 
-    public function testGetFieldNames()
+    public function testGetFieldNames(): void
     {
         $jobs = $this->db->table('job')->get()->getFieldNames();
 
@@ -83,7 +83,7 @@ public function testGetFieldNames()
         $this->assertContains('description', $jobs);
     }
 
-    public function testGetFieldData()
+    public function testGetFieldData(): void
     {
         $jobs = $this->db->table('job')->get()->getFieldData();
 
@@ -169,7 +169,7 @@ public function testGetFieldData()
         }
     }
 
-    public function testGetDataSeek()
+    public function testGetDataSeek(): void
     {
         $data = $this->db->table('job')->get();
 
@@ -186,7 +186,7 @@ public function testGetDataSeek()
         $this->assertSame('Musician', $details[0]->name);
     }
 
-    public function testGetAnotherDataSeek()
+    public function testGetAnotherDataSeek(): void
     {
         $data = $this->db->table('job')->get();
 
@@ -200,7 +200,7 @@ public function testGetAnotherDataSeek()
         $this->assertSame('Musician', $details[3]->name);
     }
 
-    public function testFreeResult()
+    public function testFreeResult(): void
     {
         $data = $this->db->table('job')->where('id', 4)->get();
 
@@ -213,21 +213,21 @@ public function testFreeResult()
         $this->assertFalse($data->resultID);
     }
 
-    public function testGetRowWithColumnName()
+    public function testGetRowWithColumnName(): void
     {
         $name = $this->db->table('user')->get()->getRow('name', 'array');
 
         $this->assertSame('Derek Jones', $name);
     }
 
-    public function testGetRowWithReturnType()
+    public function testGetRowWithReturnType(): void
     {
         $user = $this->db->table('user')->get()->getRow(0, 'array');
 
         $this->assertSame('Derek Jones', $user['name']);
     }
 
-    public function testGetRowWithCustomReturnType()
+    public function testGetRowWithCustomReturnType(): void
     {
         $testClass = new class () {
             public $id;
@@ -244,28 +244,28 @@ public function testGetRowWithCustomReturnType()
         $this->assertSame('Derek Jones', $user->name);
     }
 
-    public function testGetFirstRow()
+    public function testGetFirstRow(): void
     {
         $user = $this->db->table('user')->get()->getFirstRow();
 
         $this->assertSame('Derek Jones', $user->name);
     }
 
-    public function testGetLastRow()
+    public function testGetLastRow(): void
     {
         $user = $this->db->table('user')->get()->getLastRow();
 
         $this->assertSame('Chris Martin', $user->name);
     }
 
-    public function testGetNextRow()
+    public function testGetNextRow(): void
     {
         $user = $this->db->table('user')->get()->getNextRow();
 
         $this->assertSame('Ahmadinejad', $user->name);
     }
 
-    public function testGetPreviousRow()
+    public function testGetPreviousRow(): void
     {
         $user = $this->db->table('user')->get();
 
diff --git a/tests/system/Database/Live/GetVersionTest.php b/tests/system/Database/Live/GetVersionTest.php
index 30f4729b2944..a507a1dd5832 100644
--- a/tests/system/Database/Live/GetVersionTest.php
+++ b/tests/system/Database/Live/GetVersionTest.php
@@ -25,7 +25,7 @@ final class GetVersionTest extends CIUnitTestCase
 
     protected $migrate = false;
 
-    public function testGetVersion()
+    public function testGetVersion(): void
     {
         $version = $this->db->getVersion();
 
diff --git a/tests/system/Database/Live/GroupTest.php b/tests/system/Database/Live/GroupTest.php
index da028757e9eb..c953645dcab4 100644
--- a/tests/system/Database/Live/GroupTest.php
+++ b/tests/system/Database/Live/GroupTest.php
@@ -27,7 +27,7 @@ final class GroupTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testGroupBy()
+    public function testGroupBy(): void
     {
         $result = $this->db->table('user')
             ->select('name')
@@ -38,7 +38,7 @@ public function testGroupBy()
         $this->assertCount(4, $result);
     }
 
-    public function testHavingBy()
+    public function testHavingBy(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -61,7 +61,7 @@ public function testHavingBy()
         $this->assertCount(2, $result);
     }
 
-    public function testOrHavingBy()
+    public function testOrHavingBy(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -86,7 +86,7 @@ public function testOrHavingBy()
         $this->assertCount(2, $result);
     }
 
-    public function testHavingIn()
+    public function testHavingIn(): void
     {
         $result = $this->db->table('job')
             ->select('name')
@@ -101,7 +101,7 @@ public function testHavingIn()
         $this->assertSame('Politician', $result[1]->name);
     }
 
-    public function testorHavingIn()
+    public function testorHavingIn(): void
     {
         $result = $this->db->table('job')
             ->select('name')
@@ -117,7 +117,7 @@ public function testorHavingIn()
         $this->assertSame('Politician', $result[1]->name);
     }
 
-    public function testHavingNotIn()
+    public function testHavingNotIn(): void
     {
         $result = $this->db->table('job')
             ->select('name')
@@ -132,7 +132,7 @@ public function testHavingNotIn()
         $this->assertSame('Musician', $result[1]->name);
     }
 
-    public function testOrHavingNotIn()
+    public function testOrHavingNotIn(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -161,7 +161,7 @@ public function testOrHavingNotIn()
         $this->assertSame('Musician', $result[1]->name);
     }
 
-    public function testHavingLike()
+    public function testHavingLike(): void
     {
         $result = $this->db->table('job')
             ->select('name')
@@ -174,7 +174,7 @@ public function testHavingLike()
         $this->assertSame('Developer', $result[0]->name);
     }
 
-    public function testNotHavingLike()
+    public function testNotHavingLike(): void
     {
         $result = $this->db->table('job')
             ->select('name')
@@ -189,7 +189,7 @@ public function testNotHavingLike()
         $this->assertSame('Developer', $result[1]->name);
     }
 
-    public function testOrHavingLike()
+    public function testOrHavingLike(): void
     {
         $result = $this->db->table('job')
             ->select('name')
@@ -205,7 +205,7 @@ public function testOrHavingLike()
         $this->assertSame('Developer', $result[1]->name);
     }
 
-    public function testOrNotHavingLike()
+    public function testOrNotHavingLike(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -235,7 +235,7 @@ public function testOrNotHavingLike()
         $this->assertSame('Musician', $result[2]->name);
     }
 
-    public function testAndHavingGroupStart()
+    public function testAndHavingGroupStart(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -269,7 +269,7 @@ public function testAndHavingGroupStart()
         $this->assertSame('Accountant', $result[0]->name);
     }
 
-    public function testOrHavingGroupStart()
+    public function testOrHavingGroupStart(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -304,7 +304,7 @@ public function testOrHavingGroupStart()
         $this->assertSame('Musician', $result[1]->name);
     }
 
-    public function testNotHavingGroupStart()
+    public function testNotHavingGroupStart(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -338,7 +338,7 @@ public function testNotHavingGroupStart()
         $this->assertSame('Musician', $result[0]->name);
     }
 
-    public function testOrNotHavingGroupStart()
+    public function testOrNotHavingGroupStart(): void
     {
         $isANSISQL = in_array($this->db->DBDriver, ['OCI8'], true);
 
@@ -374,7 +374,7 @@ public function testOrNotHavingGroupStart()
         $this->assertSame('Politician', $result[2]->name);
     }
 
-    public function testAndGroups()
+    public function testAndGroups(): void
     {
         $result = $this->db->table('user')
             ->groupStart()
@@ -389,7 +389,7 @@ public function testAndGroups()
         $this->assertSame('Richard A Causey', $result[0]->name);
     }
 
-    public function testOrGroups()
+    public function testOrGroups(): void
     {
         $result = $this->db->table('user')
             ->where('country', 'Iran')
@@ -405,7 +405,7 @@ public function testOrGroups()
         $this->assertSame('Chris Martin', $result[1]->name);
     }
 
-    public function testNotGroups()
+    public function testNotGroups(): void
     {
         $result = $this->db->table('user')
             ->where('country', 'US')
@@ -420,7 +420,7 @@ public function testNotGroups()
         $this->assertSame('Derek Jones', $result[0]->name);
     }
 
-    public function testOrNotGroups()
+    public function testOrNotGroups(): void
     {
         $result = $this->db->table('user')
             ->where('country', 'US')
@@ -437,7 +437,7 @@ public function testOrNotGroups()
         $this->assertSame('Chris Martin', $result[2]->name);
     }
 
-    public function testGroupByCount()
+    public function testGroupByCount(): void
     {
         $result = $this->db->table('user')
             ->selectCount('id', 'count')
diff --git a/tests/system/Database/Live/IncrementTest.php b/tests/system/Database/Live/IncrementTest.php
index 104bb1371c51..c58edd3e7f3d 100644
--- a/tests/system/Database/Live/IncrementTest.php
+++ b/tests/system/Database/Live/IncrementTest.php
@@ -27,7 +27,7 @@ final class IncrementTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testIncrement()
+    public function testIncrement(): void
     {
         $this->hasInDatabase('job', ['name' => 'incremental', 'description' => '6']);
 
@@ -38,7 +38,7 @@ public function testIncrement()
         $this->seeInDatabase('job', ['name' => 'incremental', 'description' => '7']);
     }
 
-    public function testIncrementWithValue()
+    public function testIncrementWithValue(): void
     {
         $this->hasInDatabase('job', ['name' => 'incremental', 'description' => '6']);
 
@@ -49,7 +49,7 @@ public function testIncrementWithValue()
         $this->seeInDatabase('job', ['name' => 'incremental', 'description' => '8']);
     }
 
-    public function testResetStateAfterIncrement()
+    public function testResetStateAfterIncrement(): void
     {
         $this->hasInDatabase('job', ['name' => 'account1', 'description' => '10']);
         $this->hasInDatabase('job', ['name' => 'account2', 'description' => '10']);
@@ -63,7 +63,7 @@ public function testResetStateAfterIncrement()
         $this->seeInDatabase('job', ['name' => 'account2', 'description' => '11']);
     }
 
-    public function testDecrement()
+    public function testDecrement(): void
     {
         $this->hasInDatabase('job', ['name' => 'incremental', 'description' => '6']);
 
@@ -74,7 +74,7 @@ public function testDecrement()
         $this->seeInDatabase('job', ['name' => 'incremental', 'description' => '5']);
     }
 
-    public function testDecrementWithValue()
+    public function testDecrementWithValue(): void
     {
         $this->hasInDatabase('job', ['name' => 'incremental', 'description' => '6']);
 
@@ -85,7 +85,7 @@ public function testDecrementWithValue()
         $this->seeInDatabase('job', ['name' => 'incremental', 'description' => '4']);
     }
 
-    public function testResetStateAfterDecrement()
+    public function testResetStateAfterDecrement(): void
     {
         $this->hasInDatabase('job', ['name' => 'account1', 'description' => '10']);
         $this->hasInDatabase('job', ['name' => 'account2', 'description' => '10']);
diff --git a/tests/system/Database/Live/InsertTest.php b/tests/system/Database/Live/InsertTest.php
index cff628b19530..cd40a179dd4d 100644
--- a/tests/system/Database/Live/InsertTest.php
+++ b/tests/system/Database/Live/InsertTest.php
@@ -35,7 +35,7 @@ final class InsertTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testInsert()
+    public function testInsert(): void
     {
         $jobData = [
             'name'        => 'Grocery Sales',
@@ -47,7 +47,7 @@ public function testInsert()
         $this->seeInDatabase('job', ['name' => 'Grocery Sales']);
     }
 
-    public function testInsertBatch()
+    public function testInsertBatch(): void
     {
         $jobData = [
             [
@@ -66,7 +66,7 @@ public function testInsertBatch()
         $this->seeInDatabase('job', ['name' => 'Cab Driver']);
     }
 
-    public function testReplaceWithNoMatchingData()
+    public function testReplaceWithNoMatchingData(): void
     {
         $data = [
             'id'          => 5,
@@ -83,7 +83,7 @@ public function testReplaceWithNoMatchingData()
         $this->assertSame('Cab Driver', $row->name);
     }
 
-    public function testReplaceWithMatchingData()
+    public function testReplaceWithMatchingData(): void
     {
         $data = [
             'id'          => 1,
@@ -103,7 +103,7 @@ public function testReplaceWithMatchingData()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6726
      */
-    public function testReplaceTwice()
+    public function testReplaceTwice(): void
     {
         $builder = $this->db->table('job');
 
@@ -132,7 +132,7 @@ public function testReplaceTwice()
         $this->assertSame('Hans Schmidt', $row->name);
     }
 
-    public function testBug302()
+    public function testBug302(): void
     {
         $code = "my code \\'CodeIgniter\\Autoloader\\'";
 
@@ -145,7 +145,7 @@ public function testBug302()
         $this->seeInDatabase('misc', ['value' => $code]);
     }
 
-    public function testInsertPasswordHash()
+    public function testInsertPasswordHash(): void
     {
         $hash = '$2y$10$tNevVVMwW52V2neE3H79a.wp8ZoItrwosk54.Siz5Fbw55X9YIBsW';
 
@@ -157,7 +157,7 @@ public function testInsertPasswordHash()
         $this->seeInDatabase('misc', ['value' => $hash]);
     }
 
-    public function setupUser2()
+    public function setupUser2(): void
     {
         $this->forge->dropTable('user2', true);
 
@@ -207,7 +207,7 @@ public function setupUser2()
         $this->db->table('user2')->insertBatch($data);
     }
 
-    public function testInsertBatchWithQuery()
+    public function testInsertBatchWithQuery(): void
     {
         $this->forge = Database::forge($this->DBGroup);
 
@@ -226,7 +226,7 @@ public function testInsertBatchWithQuery()
         $this->forge->dropTable('user2', true);
     }
 
-    public function testInsertBatchWithQueryAndRawSqlAndManualColumns()
+    public function testInsertBatchWithQueryAndRawSqlAndManualColumns(): void
     {
         $this->forge = Database::forge($this->DBGroup);
 
diff --git a/tests/system/Database/Live/JoinTest.php b/tests/system/Database/Live/JoinTest.php
index 265ea31c8adc..8347f68e84a7 100644
--- a/tests/system/Database/Live/JoinTest.php
+++ b/tests/system/Database/Live/JoinTest.php
@@ -27,7 +27,7 @@ final class JoinTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testSimpleJoin()
+    public function testSimpleJoin(): void
     {
         $row = $this->db->table('job')
             ->select('job.id as job_id, job.name as job_name, user.id as user_id, user.name as user_name')
diff --git a/tests/system/Database/Live/LikeTest.php b/tests/system/Database/Live/LikeTest.php
index fe616105a466..069ce28ceed9 100644
--- a/tests/system/Database/Live/LikeTest.php
+++ b/tests/system/Database/Live/LikeTest.php
@@ -28,7 +28,7 @@ final class LikeTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testLikeDefault()
+    public function testLikeDefault(): void
     {
         $job = $this->db->table('job')->like('name', 'veloper')->get();
         $job = $job->getRow();
@@ -37,7 +37,7 @@ public function testLikeDefault()
         $this->assertSame('Developer', $job->name);
     }
 
-    public function testLikeBefore()
+    public function testLikeBefore(): void
     {
         $job = $this->db->table('job')->like('name', 'veloper', 'before')->get();
         $job = $job->getRow();
@@ -46,7 +46,7 @@ public function testLikeBefore()
         $this->assertSame('Developer', $job->name);
     }
 
-    public function testLikeAfter()
+    public function testLikeAfter(): void
     {
         $job = $this->db->table('job')->like('name', 'Develop')->get();
         $job = $job->getRow();
@@ -55,7 +55,7 @@ public function testLikeAfter()
         $this->assertSame('Developer', $job->name);
     }
 
-    public function testLikeBoth()
+    public function testLikeBoth(): void
     {
         $job = $this->db->table('job')->like('name', 'veloper', 'both')->get();
         $job = $job->getRow();
@@ -64,7 +64,7 @@ public function testLikeBoth()
         $this->assertSame('Developer', $job->name);
     }
 
-    public function testLikeCaseInsensitive()
+    public function testLikeCaseInsensitive(): void
     {
         $job = $this->db->table('job')->like('name', 'VELOPER', 'both', null, true)->get();
         $job = $job->getRow();
@@ -73,7 +73,7 @@ public function testLikeCaseInsensitive()
         $this->assertSame('Developer', $job->name);
     }
 
-    public function testOrLike()
+    public function testOrLike(): void
     {
         $jobs = $this->db->table('job')->like('name', 'ian')
             ->orLike('name', 'veloper')
@@ -86,7 +86,7 @@ public function testOrLike()
         $this->assertSame('Musician', $jobs[2]->name);
     }
 
-    public function testNotLike()
+    public function testNotLike(): void
     {
         $jobs = $this->db->table('job')
             ->notLike('name', 'veloper')
@@ -99,7 +99,7 @@ public function testNotLike()
         $this->assertSame('Musician', $jobs[2]->name);
     }
 
-    public function testOrNotLike()
+    public function testOrNotLike(): void
     {
         $jobs = $this->db->table('job')
             ->like('name', 'ian')
@@ -113,7 +113,7 @@ public function testOrNotLike()
         $this->assertSame('Musician', $jobs[2]->name);
     }
 
-    public function testLikeSpacesOrTabs()
+    public function testLikeSpacesOrTabs(): void
     {
         $builder = $this->db->table('misc');
         $spaces  = $builder->like('value', '   ')->get()->getResult();
@@ -126,7 +126,7 @@ public function testLikeSpacesOrTabs()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/7268
      */
-    public function testLikeRawSqlAndCountAllResultsAndGet()
+    public function testLikeRawSqlAndCountAllResultsAndGet(): void
     {
         $builder = $this->db->table('job');
 
@@ -147,7 +147,7 @@ public function testLikeRawSqlAndCountAllResultsAndGet()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/7268
      */
-    public function testLikeRawSqlAndGetAndCountAllResults()
+    public function testLikeRawSqlAndGetAndCountAllResults(): void
     {
         $builder = $this->db->table('job');
 
diff --git a/tests/system/Database/Live/LimitTest.php b/tests/system/Database/Live/LimitTest.php
index 2ab4000423fe..62b75fddb52b 100644
--- a/tests/system/Database/Live/LimitTest.php
+++ b/tests/system/Database/Live/LimitTest.php
@@ -27,7 +27,7 @@ final class LimitTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testLimit()
+    public function testLimit(): void
     {
         $jobs = $this->db->table('job')
             ->limit(2)
@@ -39,7 +39,7 @@ public function testLimit()
         $this->assertSame('Politician', $jobs[1]->name);
     }
 
-    public function testLimitAndOffset()
+    public function testLimitAndOffset(): void
     {
         $jobs = $this->db->table('job')
             ->limit(2, 2)
diff --git a/tests/system/Database/Live/MetadataTest.php b/tests/system/Database/Live/MetadataTest.php
index 1506c7b3d2f5..da34f03b480a 100644
--- a/tests/system/Database/Live/MetadataTest.php
+++ b/tests/system/Database/Live/MetadataTest.php
@@ -86,7 +86,7 @@ private function dropExtraneousTable(): void
         $this->db->setPrefix($oldPrefix);
     }
 
-    public function testListTablesUnconstrainedByPrefixReturnsAllTables()
+    public function testListTablesUnconstrainedByPrefixReturnsAllTables(): void
     {
         try {
             $this->createExtraneousTable();
@@ -105,7 +105,7 @@ public function testListTablesUnconstrainedByPrefixReturnsAllTables()
         }
     }
 
-    public function testListTablesConstrainedByPrefixReturnsOnlyTablesWithMatchingPrefix()
+    public function testListTablesConstrainedByPrefixReturnsOnlyTablesWithMatchingPrefix(): void
     {
         try {
             $this->createExtraneousTable();
@@ -121,7 +121,7 @@ public function testListTablesConstrainedByPrefixReturnsOnlyTablesWithMatchingPr
         }
     }
 
-    public function testListTablesConstrainedByExtraneousPrefixReturnsOnlyTheExtraneousTable()
+    public function testListTablesConstrainedByExtraneousPrefixReturnsOnlyTheExtraneousTable(): void
     {
         $oldPrefix = '';
 
diff --git a/tests/system/Database/Live/MySQLi/RawSqlTest.php b/tests/system/Database/Live/MySQLi/RawSqlTest.php
index 6356b604f011..29aaa7f12f96 100644
--- a/tests/system/Database/Live/MySQLi/RawSqlTest.php
+++ b/tests/system/Database/Live/MySQLi/RawSqlTest.php
@@ -40,7 +40,7 @@ protected function setUp(): void
         }
     }
 
-    protected function addSqlFunction()
+    protected function addSqlFunction(): void
     {
         $this->db->query('DROP FUNCTION IF EXISTS setDateTime');
 
@@ -55,7 +55,7 @@ protected function addSqlFunction()
         $this->db->query($sql);
     }
 
-    public function testRawSqlUpdateObject()
+    public function testRawSqlUpdateObject(): void
     {
         $data = [];
 
@@ -79,7 +79,7 @@ public function testRawSqlUpdateObject()
         $this->seeInDatabase('user', ['email' => 'ahmadinejad@world.com', 'created_at' => '2022-01-11 01:01:11']);
     }
 
-    public function testRawSqlSetUpdateObject()
+    public function testRawSqlSetUpdateObject(): void
     {
         $data = [];
 
@@ -103,7 +103,7 @@ public function testRawSqlSetUpdateObject()
         $this->seeInDatabase('user', ['email' => 'ahmadinejad@world.com', 'created_at' => '2022-02-11 01:01:11']);
     }
 
-    public function testRawSqlUpdateArray()
+    public function testRawSqlUpdateArray(): void
     {
         $data = [
             ['email' => 'derek@world.com', 'created_at' => new RawSql("setDateTime('2022-03-01')")],
@@ -122,7 +122,7 @@ public function testRawSqlUpdateArray()
         $this->seeInDatabase('user', ['email' => 'ahmadinejad@world.com', 'created_at' => '2022-03-11 01:01:11']);
     }
 
-    public function testRawSqlInsertArray()
+    public function testRawSqlInsertArray(): void
     {
         $data = [
             ['email' => 'pedro@world.com', 'created_at' => new RawSql("setDateTime('2022-04-01')")],
@@ -141,7 +141,7 @@ public function testRawSqlInsertArray()
         $this->seeInDatabase('user', ['email' => 'jason@world.com', 'created_at' => '2022-04-11 01:01:11']);
     }
 
-    public function testRawSqlInsertObject()
+    public function testRawSqlInsertObject(): void
     {
         $data = [];
 
@@ -167,7 +167,7 @@ public function testRawSqlInsertObject()
         $this->seeInDatabase('user', ['email' => 'jessica@world.com', 'created_at' => '2022-05-11 01:01:11']);
     }
 
-    public function testRawSqlSetInsertObject()
+    public function testRawSqlSetInsertObject(): void
     {
         $data = [];
 
diff --git a/tests/system/Database/Live/OCI8/CallStoredProcedureTest.php b/tests/system/Database/Live/OCI8/CallStoredProcedureTest.php
index 4b174a0f72a2..690b3fd3b925 100644
--- a/tests/system/Database/Live/OCI8/CallStoredProcedureTest.php
+++ b/tests/system/Database/Live/OCI8/CallStoredProcedureTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
         }
     }
 
-    public function testCallPackageProcedure()
+    public function testCallPackageProcedure(): void
     {
         $result = 0;
 
@@ -56,7 +56,7 @@ public function testCallPackageProcedure()
         $this->assertSame($result, '7');
     }
 
-    public function testCallStoredProcedure()
+    public function testCallStoredProcedure(): void
     {
         $result = 0;
 
@@ -78,7 +78,7 @@ public function testCallStoredProcedure()
         $this->assertSame($result, '7');
     }
 
-    public function testCallStoredProcedureForCursor()
+    public function testCallStoredProcedureForCursor(): void
     {
         $result = $this->db->getCursor();
 
diff --git a/tests/system/Database/Live/OCI8/LastInsertIDTest.php b/tests/system/Database/Live/OCI8/LastInsertIDTest.php
index d55e9832f179..c9131ede466c 100644
--- a/tests/system/Database/Live/OCI8/LastInsertIDTest.php
+++ b/tests/system/Database/Live/OCI8/LastInsertIDTest.php
@@ -37,7 +37,7 @@ protected function setUp(): void
         }
     }
 
-    public function testGetInsertIDWithInsert()
+    public function testGetInsertIDWithInsert(): void
     {
         $jobData = [
             'name'        => 'Grocery Sales',
@@ -50,7 +50,7 @@ public function testGetInsertIDWithInsert()
         $this->assertSame($actual, 5);
     }
 
-    public function testGetInsertIDWithQuery()
+    public function testGetInsertIDWithQuery(): void
     {
         $this->db->query('INSERT INTO "db_job" ("name", "description") VALUES (?, ?)', ['Grocery Sales', 'Discount!']);
         $actual = $this->db->insertID();
@@ -58,7 +58,7 @@ public function testGetInsertIDWithQuery()
         $this->assertSame($actual, 5);
     }
 
-    public function testGetInsertIDWithHasCommentQuery()
+    public function testGetInsertIDWithHasCommentQuery(): void
     {
         $sql = <<<'SQL'
             -- INSERT INTO "db_misc" ("key", "value") VALUES ('key', 'value')
@@ -74,7 +74,7 @@ public function testGetInsertIDWithHasCommentQuery()
         $this->assertSame($actual, 5);
     }
 
-    public function testGetInsertIDWithPreparedQuery()
+    public function testGetInsertIDWithPreparedQuery(): void
     {
         $query = $this->db->prepare(static function ($db) {
             $sql = 'INSERT INTO "db_job" ("name", "description") VALUES (?, ?)';
diff --git a/tests/system/Database/Live/OrderTest.php b/tests/system/Database/Live/OrderTest.php
index 378b149f4b84..a491ff349cd8 100644
--- a/tests/system/Database/Live/OrderTest.php
+++ b/tests/system/Database/Live/OrderTest.php
@@ -27,7 +27,7 @@ final class OrderTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testOrderAscending()
+    public function testOrderAscending(): void
     {
         $jobs = $this->db->table('job')
             ->orderBy('name', 'asc')
@@ -41,7 +41,7 @@ public function testOrderAscending()
         $this->assertSame('Politician', $jobs[3]->name);
     }
 
-    public function testOrderDescending()
+    public function testOrderDescending(): void
     {
         $jobs = $this->db->table('job')
             ->orderBy('name', 'desc')
@@ -55,7 +55,7 @@ public function testOrderDescending()
         $this->assertSame('Politician', $jobs[0]->name);
     }
 
-    public function testMultipleOrderValues()
+    public function testMultipleOrderValues(): void
     {
         $users = $this->db->table('user')
             ->orderBy('country', 'asc')
@@ -70,7 +70,7 @@ public function testMultipleOrderValues()
         $this->assertSame('Derek Jones', $users[3]->name);
     }
 
-    public function testOrderRandom()
+    public function testOrderRandom(): void
     {
         $sql = $this->db->table('job')
             ->orderBy('name', 'random')
diff --git a/tests/system/Database/Live/PreparedQueryTest.php b/tests/system/Database/Live/PreparedQueryTest.php
index edbd044a21fe..2bb2c7419696 100644
--- a/tests/system/Database/Live/PreparedQueryTest.php
+++ b/tests/system/Database/Live/PreparedQueryTest.php
@@ -50,7 +50,7 @@ protected function tearDown(): void
         }
     }
 
-    public function testPrepareReturnsPreparedQuery()
+    public function testPrepareReturnsPreparedQuery(): void
     {
         $this->query = $this->db->prepare(static fn ($db) => $db->table('user')->insert([
             'name'    => 'a',
@@ -79,7 +79,7 @@ public function testPrepareReturnsPreparedQuery()
         $this->assertSame($expected, $this->query->getQueryString());
     }
 
-    public function testPrepareReturnsManualPreparedQuery()
+    public function testPrepareReturnsManualPreparedQuery(): void
     {
         $this->query = $this->db->prepare(static function ($db) {
             $sql = "INSERT INTO {$db->protectIdentifiers($db->DBPrefix . 'user')} ("
@@ -107,7 +107,7 @@ public function testPrepareReturnsManualPreparedQuery()
         $this->assertSame($expected, $this->query->getQueryString());
     }
 
-    public function testExecuteRunsQueryAndReturnsTrue()
+    public function testExecuteRunsQueryAndReturnsTrue(): void
     {
         $this->query = $this->db->prepare(static fn ($db) => $db->table('user')->insert([
             'name'    => 'a',
@@ -123,7 +123,7 @@ public function testExecuteRunsQueryAndReturnsTrue()
         $this->seeInDatabase($this->db->DBPrefix . 'user', ['name' => 'bar', 'email' => 'bar@example.com']);
     }
 
-    public function testExecuteRunsQueryManualAndReturnsTrue()
+    public function testExecuteRunsQueryManualAndReturnsTrue(): void
     {
         $this->query = $this->db->prepare(static function ($db) {
             $sql = "INSERT INTO {$db->protectIdentifiers($db->DBPrefix . 'user')} ("
@@ -142,7 +142,7 @@ public function testExecuteRunsQueryManualAndReturnsTrue()
         $this->seeInDatabase($this->db->DBPrefix . 'user', ['name' => 'bar', 'email' => 'bar@example.com']);
     }
 
-    public function testExecuteRunsQueryAndReturnsFalse()
+    public function testExecuteRunsQueryAndReturnsFalse(): void
     {
         $this->query = $this->db->prepare(static fn ($db) => $db->table('without_auto_increment')->insert([
             'key'   => 'a',
@@ -160,7 +160,7 @@ public function testExecuteRunsQueryAndReturnsFalse()
         $this->dontSeeInDatabase($this->db->DBPrefix . 'without_auto_increment', ['key' => 'foo1', 'value' => 'baz']);
     }
 
-    public function testExecuteRunsQueryManualAndReturnsFalse()
+    public function testExecuteRunsQueryManualAndReturnsFalse(): void
     {
         $this->query = $this->db->prepare(static function ($db) {
             $sql = "INSERT INTO {$db->protectIdentifiers($db->DBPrefix . 'without_auto_increment')} ("
@@ -182,7 +182,7 @@ public function testExecuteRunsQueryManualAndReturnsFalse()
         $this->dontSeeInDatabase($this->db->DBPrefix . 'without_auto_increment', ['key' => 'foo1', 'value' => 'baz']);
     }
 
-    public function testExecuteSelectQueryAndCheckTypeAndResult()
+    public function testExecuteSelectQueryAndCheckTypeAndResult(): void
     {
         $this->query = $this->db->prepare(static fn ($db) => $db->table('user')->select('name, email, country')->where([
             'name' => 'foo',
@@ -196,7 +196,7 @@ public function testExecuteSelectQueryAndCheckTypeAndResult()
         $this->assertSame($expectedRow, $result->getRowArray());
     }
 
-    public function testExecuteSelectQueryManualAndCheckTypeAndResult()
+    public function testExecuteSelectQueryManualAndCheckTypeAndResult(): void
     {
         $this->query = $this->db->prepare(static function ($db) {
             $sql = 'SELECT '
@@ -217,7 +217,7 @@ public function testExecuteSelectQueryManualAndCheckTypeAndResult()
         $this->assertSame($expectedRow, $result->getRowArray());
     }
 
-    public function testExecuteRunsInvalidQuery()
+    public function testExecuteRunsInvalidQuery(): void
     {
         $this->expectException(DatabaseException::class);
 
@@ -230,7 +230,7 @@ public function testExecuteRunsInvalidQuery()
         $this->query->execute('foo', 'foo@example.com', 'US');
     }
 
-    public function testDeallocatePreparedQueryThenTryToExecute()
+    public function testDeallocatePreparedQueryThenTryToExecute(): void
     {
         $this->query = $this->db->prepare(static fn ($db) => $db->table('user')->insert([
             'name'    => 'a',
@@ -247,7 +247,7 @@ public function testDeallocatePreparedQueryThenTryToExecute()
         $this->query->execute('bar', 'bar@example.com', 'GB');
     }
 
-    public function testDeallocatePreparedQueryThenTryToClose()
+    public function testDeallocatePreparedQueryThenTryToClose(): void
     {
         $this->query = $this->db->prepare(
             static fn ($db) => $db->table('user')->insert([
diff --git a/tests/system/Database/Live/PretendTest.php b/tests/system/Database/Live/PretendTest.php
index 3eae20e97cd2..a9c39ef3688f 100644
--- a/tests/system/Database/Live/PretendTest.php
+++ b/tests/system/Database/Live/PretendTest.php
@@ -30,7 +30,7 @@ protected function tearDown(): void
         $this->db->pretend(false);
     }
 
-    public function testPretendReturnsQueryObject()
+    public function testPretendReturnsQueryObject(): void
     {
         $result = $this->db->pretend(false)
             ->table('user')
diff --git a/tests/system/Database/Live/SQLite/AlterTableTest.php b/tests/system/Database/Live/SQLite/AlterTableTest.php
index d29d09e32e0c..74d53cb0783d 100644
--- a/tests/system/Database/Live/SQLite/AlterTableTest.php
+++ b/tests/system/Database/Live/SQLite/AlterTableTest.php
@@ -56,7 +56,7 @@ protected function setUp(): void
         $this->dropTables();
     }
 
-    private function dropTables()
+    private function dropTables(): void
     {
         $this->forge->dropTable('aliens', true);
         $this->forge->dropTable('aliens_fk', true);
@@ -66,7 +66,7 @@ private function dropTables()
         $this->forge->dropTable('foo_fk', true);
     }
 
-    public function testFromTableThrowsOnNoTable()
+    public function testFromTableThrowsOnNoTable(): void
     {
         $this->expectException(DataException::class);
         $this->expectExceptionMessage('Table "foo" was not found in the current database.');
@@ -74,7 +74,7 @@ public function testFromTableThrowsOnNoTable()
         $this->table->fromTable('foo');
     }
 
-    public function testFromTableFillsDetails()
+    public function testFromTableFillsDetails(): void
     {
         $this->createTable();
 
@@ -111,7 +111,7 @@ public function testFromTableFillsDetails()
         $this->assertSame(['fields' => ['id'], 'type' => 'primary'], $keys['primary']);
     }
 
-    public function testDropColumnSuccess()
+    public function testDropColumnSuccess(): void
     {
         $this->createTable();
 
@@ -129,7 +129,7 @@ public function testDropColumnSuccess()
         $this->assertContains('email', $columns);
     }
 
-    public function testDropColumnMaintainsKeys()
+    public function testDropColumnMaintainsKeys(): void
     {
         $this->createTable();
 
@@ -151,7 +151,7 @@ public function testDropColumnMaintainsKeys()
         $this->assertTrue($result);
     }
 
-    public function testDropColumnDropCompositeKey()
+    public function testDropColumnDropCompositeKey(): void
     {
         $this->forge->dropTable('actions', true);
 
@@ -191,7 +191,7 @@ public function testDropColumnDropCompositeKey()
         $this->forge->dropTable('actions');
     }
 
-    public function testModifyColumnSuccess()
+    public function testModifyColumnSuccess(): void
     {
         $this->createTable('janky');
 
@@ -214,7 +214,7 @@ public function testModifyColumnSuccess()
         $this->assertTrue($this->db->fieldExists('serial', 'janky'));
     }
 
-    public function testDropForeignKeySuccess()
+    public function testDropForeignKeySuccess(): void
     {
         $this->createTable('aliens');
 
@@ -232,7 +232,7 @@ public function testDropForeignKeySuccess()
         $this->assertEmpty($keys);
     }
 
-    public function testProcessCopiesOldData()
+    public function testProcessCopiesOldData(): void
     {
         $this->createTable();
 
@@ -259,7 +259,7 @@ public function testProcessCopiesOldData()
         $this->seeInDatabase('foo', ['email' => 'funkalicious@example.com']);
     }
 
-    protected function createTable(string $tableName = 'foo')
+    protected function createTable(string $tableName = 'foo'): void
     {
         // Create support table for foreign keys
         $this->forge->addField([
diff --git a/tests/system/Database/Live/SQLite/GetIndexDataTest.php b/tests/system/Database/Live/SQLite/GetIndexDataTest.php
index 74074b17b823..7a3c649c9392 100644
--- a/tests/system/Database/Live/SQLite/GetIndexDataTest.php
+++ b/tests/system/Database/Live/SQLite/GetIndexDataTest.php
@@ -55,7 +55,7 @@ protected function setUp(): void
         $this->forge = Database::forge($config);
     }
 
-    public function testGetIndexData()
+    public function testGetIndexData(): void
     {
         // INTEGER PRIMARY KEY AUTO_INCREMENT doesn't get an index by default
         $this->forge->addField([
diff --git a/tests/system/Database/Live/SelectTest.php b/tests/system/Database/Live/SelectTest.php
index a6248197aacc..c32f5e116828 100644
--- a/tests/system/Database/Live/SelectTest.php
+++ b/tests/system/Database/Live/SelectTest.php
@@ -27,7 +27,7 @@ final class SelectTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testSelectAllByDefault()
+    public function testSelectAllByDefault(): void
     {
         $row = $this->db->table('job')->get()->getRowArray();
 
@@ -36,7 +36,7 @@ public function testSelectAllByDefault()
         $this->assertArrayHasKey('description', $row);
     }
 
-    public function testSelectSingleColumn()
+    public function testSelectSingleColumn(): void
     {
         $row = $this->db->table('job')->select('name')->get()->getRowArray();
 
@@ -45,7 +45,7 @@ public function testSelectSingleColumn()
         $this->assertArrayNotHasKey('description', $row);
     }
 
-    public function testSelectMultipleColumns()
+    public function testSelectMultipleColumns(): void
     {
         $row = $this->db->table('job')->select('name, description')->get()->getRowArray();
 
@@ -54,84 +54,84 @@ public function testSelectMultipleColumns()
         $this->assertArrayHasKey('description', $row);
     }
 
-    public function testSelectMax()
+    public function testSelectMax(): void
     {
         $result = $this->db->table('job')->selectMax('id')->get()->getRow();
 
         $this->assertSame(4, (int) $result->id);
     }
 
-    public function testSelectMaxWithAlias()
+    public function testSelectMaxWithAlias(): void
     {
         $result = $this->db->table('job')->selectMax('id', 'xam')->get()->getRow();
 
         $this->assertSame(4, (int) $result->xam);
     }
 
-    public function testSelectMin()
+    public function testSelectMin(): void
     {
         $result = $this->db->table('job')->selectMin('id')->get()->getRow();
 
         $this->assertSame(1, (int) $result->id);
     }
 
-    public function testSelectMinWithAlias()
+    public function testSelectMinWithAlias(): void
     {
         $result = $this->db->table('job')->selectMin('id', 'xam')->get()->getRow();
 
         $this->assertSame(1, (int) $result->xam);
     }
 
-    public function testSelectAvg()
+    public function testSelectAvg(): void
     {
         $result = $this->db->table('job')->selectAvg('id')->get()->getRow();
 
         $this->assertSame(2.5, (float) $result->id);
     }
 
-    public function testSelectAvgWithAlias()
+    public function testSelectAvgWithAlias(): void
     {
         $result = $this->db->table('job')->selectAvg('id', 'xam')->get()->getRow();
 
         $this->assertSame(2.5, (float) $result->xam);
     }
 
-    public function testSelectSum()
+    public function testSelectSum(): void
     {
         $result = $this->db->table('job')->selectSum('id')->get()->getRow();
 
         $this->assertSame(10, (int) $result->id);
     }
 
-    public function testSelectSumWithAlias()
+    public function testSelectSumWithAlias(): void
     {
         $result = $this->db->table('job')->selectSum('id', 'xam')->get()->getRow();
 
         $this->assertSame(10, (int) $result->xam);
     }
 
-    public function testSelectCount()
+    public function testSelectCount(): void
     {
         $result = $this->db->table('job')->selectCount('id')->get()->getRow();
 
         $this->assertSame(4, (int) $result->id);
     }
 
-    public function testSelectCountWithAlias()
+    public function testSelectCountWithAlias(): void
     {
         $result = $this->db->table('job')->selectCount('id', 'xam')->get()->getRow();
 
         $this->assertSame(4, (int) $result->xam);
     }
 
-    public function testSelectDistinctWorkTogether()
+    public function testSelectDistinctWorkTogether(): void
     {
         $users = $this->db->table('user')->select('country')->distinct()->get()->getResult();
 
         $this->assertCount(3, $users);
     }
 
-    public function testSelectDistinctCanBeTurnedOff()
+    public function testSelectDistinctCanBeTurnedOff(): void
     {
         $users = $this->db->table('user')->select('country')->distinct(false)->get()->getResult();
 
@@ -141,7 +141,7 @@ public function testSelectDistinctCanBeTurnedOff()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1226
      */
-    public function testSelectWithMultipleWheresOnSameColumn()
+    public function testSelectWithMultipleWheresOnSameColumn(): void
     {
         $users = $this->db->table('user')
             ->where('id', 1)
@@ -159,7 +159,7 @@ public function testSelectWithMultipleWheresOnSameColumn()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1226
      */
-    public function testSelectWithMultipleWheresOnSameColumnAgain()
+    public function testSelectWithMultipleWheresOnSameColumnAgain(): void
     {
         $users = $this->db->table('user')
             ->whereIn('id', [1, 2])
diff --git a/tests/system/Database/Live/TransactionDBDebugFalseTest.php b/tests/system/Database/Live/TransactionDBDebugFalseTest.php
index 4a829698e49c..bc35c2d89041 100644
--- a/tests/system/Database/Live/TransactionDBDebugFalseTest.php
+++ b/tests/system/Database/Live/TransactionDBDebugFalseTest.php
@@ -32,7 +32,7 @@ protected function tearDown(): void
         $this->enableDBDebug();
     }
 
-    public function testTransStartTransException()
+    public function testTransStartTransException(): void
     {
         $builder = $this->db->table('job');
 
diff --git a/tests/system/Database/Live/TransactionDBDebugTrueTest.php b/tests/system/Database/Live/TransactionDBDebugTrueTest.php
index 8770de5066f7..9e7ecfcde6d0 100644
--- a/tests/system/Database/Live/TransactionDBDebugTrueTest.php
+++ b/tests/system/Database/Live/TransactionDBDebugTrueTest.php
@@ -57,7 +57,7 @@ protected function enableDBDebug(): void
         $this->setPrivateProperty($this->db, 'DBDebug', true);
     }
 
-    public function testTransStart()
+    public function testTransStart(): void
     {
         $builder = $this->db->table('job');
 
@@ -83,7 +83,7 @@ public function testTransStart()
         $this->dontSeeInDatabase('job', ['name' => 'Grocery Sales']);
     }
 
-    public function testTransStartTransException()
+    public function testTransStartTransException(): void
     {
         $builder = $this->db->table('job');
         $e       = null;
@@ -114,7 +114,7 @@ public function testTransStartTransException()
         $this->dontSeeInDatabase('job', ['name' => 'Grocery Sales']);
     }
 
-    public function testTransStrictTrue()
+    public function testTransStrictTrue(): void
     {
         $builder = $this->db->table('job');
 
@@ -159,7 +159,7 @@ public function testTransStrictTrue()
         $this->dontSeeInDatabase('job', ['name' => 'Comedian']);
     }
 
-    public function testTransStrictFalse()
+    public function testTransStrictFalse(): void
     {
         $builder = $this->db->table('job');
 
@@ -206,7 +206,7 @@ public function testTransStrictFalse()
         $this->seeInDatabase('job', ['name' => 'Comedian']);
     }
 
-    public function testTransBegin()
+    public function testTransBegin(): void
     {
         $builder = $this->db->table('job');
 
diff --git a/tests/system/Database/Live/TransactionTest.php b/tests/system/Database/Live/TransactionTest.php
index a2052e1a3236..6a3c12262d6b 100644
--- a/tests/system/Database/Live/TransactionTest.php
+++ b/tests/system/Database/Live/TransactionTest.php
@@ -55,7 +55,7 @@ protected function enableDBDebug(): void
         $this->setPrivateProperty($this->db, 'DBDebug', true);
     }
 
-    public function testTransStartDBDebugTrue()
+    public function testTransStartDBDebugTrue(): void
     {
         $this->enableDBDebug();
 
@@ -105,7 +105,7 @@ public function testTransStartDBDebugTrue()
         $this->dontSeeInDatabase('job', ['name' => 'Grocery Sales']);
     }
 
-    public function testTransStartDBDebugFalse()
+    public function testTransStartDBDebugFalse(): void
     {
         $this->disableDBDebug();
 
@@ -138,7 +138,7 @@ public function testTransStartDBDebugFalse()
         $this->enableDBDebug();
     }
 
-    public function testTransStrictTrueAndDBDebugFalse()
+    public function testTransStrictTrueAndDBDebugFalse(): void
     {
         $this->disableDBDebug();
 
@@ -187,7 +187,7 @@ public function testTransStrictTrueAndDBDebugFalse()
         $this->enableDBDebug();
     }
 
-    public function testTransStrictFalseAndDBDebugFalse()
+    public function testTransStrictFalseAndDBDebugFalse(): void
     {
         $this->disableDBDebug();
 
diff --git a/tests/system/Database/Live/UpdateTest.php b/tests/system/Database/Live/UpdateTest.php
index db998100395d..1c6ae8a430b6 100644
--- a/tests/system/Database/Live/UpdateTest.php
+++ b/tests/system/Database/Live/UpdateTest.php
@@ -36,7 +36,7 @@ final class UpdateTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testUpdateSetsAllWithoutWhere()
+    public function testUpdateSetsAllWithoutWhere(): void
     {
         $this->db->table('user')->update(['name' => 'Bobby']);
 
@@ -48,7 +48,7 @@ public function testUpdateSetsAllWithoutWhere()
         $this->assertSame('Bobby', $result[3]->name);
     }
 
-    public function testUpdateSetsAllWithoutWhereAndLimit()
+    public function testUpdateSetsAllWithoutWhereAndLimit(): void
     {
         try {
             $this->db->table('user')->update(['name' => 'Bobby'], null, 1);
@@ -76,7 +76,7 @@ public function testUpdateSetsAllWithoutWhereAndLimit()
         }
     }
 
-    public function testUpdateWithWhere()
+    public function testUpdateWithWhere(): void
     {
         $this->db->table('user')->update(['name' => 'Bobby'], ['country' => 'US']);
 
@@ -93,7 +93,7 @@ public function testUpdateWithWhere()
         $this->assertCount(2, $rows);
     }
 
-    public function testUpdateWithWhereAndLimit()
+    public function testUpdateWithWhereAndLimit(): void
     {
         try {
             $this->db->table('user')->update(['name' => 'Bobby'], ['country' => 'US'], 1);
@@ -111,7 +111,7 @@ public function testUpdateWithWhereAndLimit()
         }
     }
 
-    public function testUpdateBatch()
+    public function testUpdateBatch(): void
     {
         $data = [
             [
@@ -136,7 +136,7 @@ public function testUpdateBatch()
         ]);
     }
 
-    public function testUpdateWithWhereSameColumn()
+    public function testUpdateWithWhereSameColumn(): void
     {
         $this->db->table('user')->update(['country' => 'CA'], ['country' => 'US']);
 
@@ -153,7 +153,7 @@ public function testUpdateWithWhereSameColumn()
         $this->assertCount(2, $rows);
     }
 
-    public function testUpdateWithWhereSameColumn2()
+    public function testUpdateWithWhereSameColumn2(): void
     {
         // calling order: set() -> where()
         $this->db->table('user')
@@ -174,7 +174,7 @@ public function testUpdateWithWhereSameColumn2()
         $this->assertCount(2, $rows);
     }
 
-    public function testUpdateWithWhereSameColumn3()
+    public function testUpdateWithWhereSameColumn3(): void
     {
         // calling order: where() -> set() in update()
         $this->db->table('user')
@@ -197,7 +197,7 @@ public function testUpdateWithWhereSameColumn3()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/324
      */
-    public function testUpdatePeriods()
+    public function testUpdatePeriods(): void
     {
         $this->db->table('misc')
             ->where('key', 'spaces and tabs')
@@ -213,7 +213,7 @@ public function testUpdatePeriods()
     /**
      * @see https://codeigniter4.github.io/CodeIgniter4/database/query_builder.html#updating-data
      */
-    public function testSetWithoutEscape()
+    public function testSetWithoutEscape(): void
     {
         $this->db->table('job')
             ->set('description', $this->db->escapeIdentifiers('name'), false)
@@ -225,7 +225,7 @@ public function testSetWithoutEscape()
         ]);
     }
 
-    public function testSetWithBoolean()
+    public function testSetWithBoolean(): void
     {
         $this->db->table('type_test')
             ->set('type_boolean', false)
@@ -244,7 +244,7 @@ public function testSetWithBoolean()
         ]);
     }
 
-    public function testUpdateBatchTwoConstraints()
+    public function testUpdateBatchTwoConstraints(): void
     {
         if (version_compare($this->db->getVersion(), '3.33.0') < 0) {
             $this->markTestSkipped('This SQLite version does not support this test.');
@@ -275,7 +275,7 @@ public function testUpdateBatchTwoConstraints()
         ]);
     }
 
-    public function testUpdateBatchConstraintsRawSqlAndAlias()
+    public function testUpdateBatchConstraintsRawSqlAndAlias(): void
     {
         if (version_compare($this->db->getVersion(), '3.33.0') < 0) {
             $this->markTestSkipped('This SQLite version does not support this test.');
@@ -329,7 +329,7 @@ public function testUpdateBatchConstraintsRawSqlAndAlias()
         ]);
     }
 
-    public function testUpdateBatchUpdateFieldsAndAlias()
+    public function testUpdateBatchUpdateFieldsAndAlias(): void
     {
         if ($this->db->DBDriver === 'SQLite3' && ! (version_compare($this->db->getVersion(), '3.33.0') >= 0)) {
             $this->markTestSkipped('Only SQLite 3.33 and newer can complete this test.');
@@ -420,7 +420,7 @@ public function testUpdateBatchUpdateFieldsAndAlias()
         $this->seeInDatabase('user', ['name' => 'Should Change', 'country' => 'UK']);
     }
 
-    public function testUpdateBatchWithoutOnConstraint()
+    public function testUpdateBatchWithoutOnConstraint(): void
     {
         if ($this->db->DBDriver === 'SQLite3' && ! (version_compare($this->db->getVersion(), '3.33.0') >= 0)) {
             $this->markTestSkipped('Only SQLite 3.33 and newer can complete this test.');
@@ -462,7 +462,7 @@ public function testUpdateBatchWithoutOnConstraint()
         }
     }
 
-    public function testRawSqlConstraint()
+    public function testRawSqlConstraint(): void
     {
         if ($this->db->DBDriver === 'SQLite3' && ! (version_compare($this->db->getVersion(), '3.33.0') >= 0)) {
             $this->markTestSkipped('Only SQLite 3.33 and newer can complete this test.');
@@ -486,7 +486,7 @@ public function testRawSqlConstraint()
         $this->seeInDatabase('user', ['email' => 'derek@world.com', 'country' => 'Germany']);
     }
 
-    public function testRawSqlConstraintWithKey()
+    public function testRawSqlConstraintWithKey(): void
     {
         if ($this->db->DBDriver === 'SQLite3' && ! (version_compare($this->db->getVersion(), '3.33.0') >= 0)) {
             $this->markTestSkipped('Only SQLite 3.33 and newer can complete this test.');
@@ -510,7 +510,7 @@ public function testRawSqlConstraintWithKey()
         $this->seeInDatabase('user', ['email' => 'derek@world.com', 'country' => 'Germany']);
     }
 
-    public function testNoConstraintFound()
+    public function testNoConstraintFound(): void
     {
         $jobData = [
             'name'        => 'Programmer',
@@ -524,7 +524,7 @@ public function testNoConstraintFound()
             ->updateBatch($jobData);
     }
 
-    public function testUpdateBatchWithQuery()
+    public function testUpdateBatchWithQuery(): void
     {
         $this->forge = Database::forge($this->DBGroup);
 
diff --git a/tests/system/Database/Live/UpsertTest.php b/tests/system/Database/Live/UpsertTest.php
index 51289b879da5..8c9fcb694c72 100644
--- a/tests/system/Database/Live/UpsertTest.php
+++ b/tests/system/Database/Live/UpsertTest.php
@@ -37,7 +37,7 @@ final class UpsertTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testUpsertOnUniqueIndex()
+    public function testUpsertOnUniqueIndex(): void
     {
         $userData = [
             'email'   => 'upsertone@test.com',
@@ -50,7 +50,7 @@ public function testUpsertOnUniqueIndex()
         $this->seeInDatabase('user', ['name' => 'Upsert One']);
     }
 
-    public function testUpsertAndUpsertBatchWithObject()
+    public function testUpsertAndUpsertBatchWithObject(): void
     {
         $data = [];
 
@@ -119,7 +119,7 @@ public function testUpsertAndUpsertBatchWithObject()
         }
     }
 
-    public function testUpsertChangePrimaryKeyOnUniqueIndex()
+    public function testUpsertChangePrimaryKeyOnUniqueIndex(): void
     {
         $userData = [
             'id'      => 5,
@@ -145,7 +145,7 @@ public function testUpsertChangePrimaryKeyOnUniqueIndex()
         }
     }
 
-    public function testNoConstraintFound()
+    public function testNoConstraintFound(): void
     {
         $jobData = [
             'name'        => 'Programmer',
@@ -164,7 +164,7 @@ public function testNoConstraintFound()
         }
     }
 
-    public function testGetCompiledUpsert()
+    public function testGetCompiledUpsert(): void
     {
         switch ($this->db->DBDriver) {
             case 'MySQLi':
@@ -246,7 +246,7 @@ public function testGetCompiledUpsert()
             ->getCompiledUpsert());
     }
 
-    public function testGetCompiledUpsertBatch()
+    public function testGetCompiledUpsertBatch(): void
     {
         $userData = [
             [
@@ -282,7 +282,7 @@ public function testGetCompiledUpsertBatch()
         $this->assertStringContainsString($insertString, $sql);
     }
 
-    public function testUpsertCauseConstraintError()
+    public function testUpsertCauseConstraintError(): void
     {
         $userData = [
             'id'      => 1,
@@ -301,7 +301,7 @@ public function testUpsertCauseConstraintError()
             ->upsert($userData);
     }
 
-    public function testUpsertBatchOnUniqueIndex()
+    public function testUpsertBatchOnUniqueIndex(): void
     {
         $userData = [
             [
@@ -328,7 +328,7 @@ public function testUpsertBatchOnUniqueIndex()
         $this->seeInDatabase('user', ['name' => 'Upsert Three']);
     }
 
-    public function testSetDataUpsertBatch()
+    public function testSetDataUpsertBatch(): void
     {
         $userData = [
             [
@@ -355,7 +355,7 @@ public function testSetDataUpsertBatch()
         $this->seeInDatabase('user', ['name' => 'Upsert Three']);
     }
 
-    public function testUpsertBatchWithOnConflictAndUpdateFields()
+    public function testUpsertBatchWithOnConflictAndUpdateFields(): void
     {
         $userData = [
             [
@@ -396,7 +396,7 @@ public function testUpsertBatchWithOnConflictAndUpdateFields()
         $this->assertSame('El Salvador', $data[4]->country);
     }
 
-    public function testUpsertWithMatchingDataOnUniqueIndexandPrimaryKey()
+    public function testUpsertWithMatchingDataOnUniqueIndexandPrimaryKey(): void
     {
         $data = [
             'id'      => 6,
@@ -429,7 +429,7 @@ public function testUpsertWithMatchingDataOnUniqueIndexandPrimaryKey()
         $this->assertNotSame($original->name, $row->name);
     }
 
-    public function testUpsertBatchOnPrimaryKey()
+    public function testUpsertBatchOnPrimaryKey(): void
     {
         $userData = [
             [
@@ -474,7 +474,7 @@ public function testUpsertBatchOnPrimaryKey()
         $this->assertSame('Upsert Three On Id', $row3->name);
     }
 
-    public function testUpsertBatchOnNullAutoIncrement()
+    public function testUpsertBatchOnNullAutoIncrement(): void
     {
         $userData = [
             [
@@ -519,7 +519,7 @@ public function testUpsertBatchOnNullAutoIncrement()
         $this->assertSame('Null Three', $row3->name);
     }
 
-    public function testUpsertBatchMultipleConstraints()
+    public function testUpsertBatchMultipleConstraints(): void
     {
         $data = [
             [
@@ -555,7 +555,7 @@ public function testUpsertBatchMultipleConstraints()
         }
     }
 
-    public function testSetBatchOneRow()
+    public function testSetBatchOneRow(): void
     {
         $data = [
             [
@@ -616,7 +616,7 @@ public function testSetBatchOneRow()
         }
     }
 
-    public function testUpsertNoData()
+    public function testUpsertNoData(): void
     {
         $this->expectException(DatabaseException::class);
         $this->expectExceptionMessage('upsertBatch() has no data.');
@@ -624,7 +624,7 @@ public function testUpsertNoData()
         $this->db->table('user')->onConstraint('email')->upsertBatch();
     }
 
-    public function testUpsertWithMultipleSet()
+    public function testUpsertWithMultipleSet(): void
     {
         $builder = $this->db->table('user');
 
@@ -645,7 +645,7 @@ public function testUpsertWithMultipleSet()
         $this->seeInDatabase('user', ['email' => 'jarvis@example.com', 'name' => 'Jarvis', 'country' => $dt]);
     }
 
-    public function testUpsertWithTestModeAndGetCompiledUpsert()
+    public function testUpsertWithTestModeAndGetCompiledUpsert(): void
     {
         $userData = [
             'email'   => 'upsertone@test.com',
@@ -659,7 +659,7 @@ public function testUpsertWithTestModeAndGetCompiledUpsert()
         $this->assertStringContainsString('upsertone@test.com', $sql);
     }
 
-    public function testUpsertBatchWithQuery()
+    public function testUpsertBatchWithQuery(): void
     {
         $this->forge = Database::forge($this->DBGroup);
 
diff --git a/tests/system/Database/Live/WhereTest.php b/tests/system/Database/Live/WhereTest.php
index 6687df7d2e9f..b3e5f125be59 100644
--- a/tests/system/Database/Live/WhereTest.php
+++ b/tests/system/Database/Live/WhereTest.php
@@ -27,7 +27,7 @@ final class WhereTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testWhereSimpleKeyValue()
+    public function testWhereSimpleKeyValue(): void
     {
         $row = $this->db->table('job')->where('id', 1)->get()->getRow();
 
@@ -35,14 +35,14 @@ public function testWhereSimpleKeyValue()
         $this->assertSame('Developer', $row->name);
     }
 
-    public function testWhereCustomKeyValue()
+    public function testWhereCustomKeyValue(): void
     {
         $jobs = $this->db->table('job')->where('id !=', 1)->get()->getResult();
 
         $this->assertCount(3, $jobs);
     }
 
-    public function testWhereArray()
+    public function testWhereArray(): void
     {
         $jobs = $this->db->table('job')->where([
             'id >'    => 2,
@@ -55,7 +55,7 @@ public function testWhereArray()
         $this->assertSame('Musician', $job->name);
     }
 
-    public function testWhereCustomString()
+    public function testWhereCustomString(): void
     {
         $jobs = $this->db->table('job')->where("id > 2 AND name != 'Accountant'")
             ->get()
@@ -67,7 +67,7 @@ public function testWhereCustomString()
         $this->assertSame('Musician', $job->name);
     }
 
-    public function testOrWhere()
+    public function testOrWhere(): void
     {
         $jobs = $this->db->table('job')
             ->where('name !=', 'Accountant')
@@ -81,7 +81,7 @@ public function testOrWhere()
         $this->assertSame('Musician', $jobs[2]->name);
     }
 
-    public function testOrWhereSameColumn()
+    public function testOrWhereSameColumn(): void
     {
         $jobs = $this->db->table('job')
             ->where('name', 'Developer')
@@ -94,7 +94,7 @@ public function testOrWhereSameColumn()
         $this->assertSame('Politician', $jobs[1]->name);
     }
 
-    public function testWhereIn()
+    public function testWhereIn(): void
     {
         $jobs = $this->db->table('job')
             ->whereIn('name', ['Politician', 'Accountant'])
@@ -106,7 +106,7 @@ public function testWhereIn()
         $this->assertSame('Accountant', $jobs[1]->name);
     }
 
-    public function testWhereNotIn()
+    public function testWhereNotIn(): void
     {
         $jobs = $this->db->table('job')
             ->whereNotIn('name', ['Politician', 'Accountant'])
@@ -118,7 +118,7 @@ public function testWhereNotIn()
         $this->assertSame('Musician', $jobs[1]->name);
     }
 
-    public function testSubQuery()
+    public function testSubQuery(): void
     {
         $subQuery = $this->db->table('job')
             ->select('id')
@@ -144,7 +144,7 @@ public function testSubQuery()
         $this->assertSame('Musician', $jobs[2]->name);
     }
 
-    public function testSubQueryAnotherType()
+    public function testSubQueryAnotherType(): void
     {
         $subQuery = $this->db->table('job')
             ->select('id')
@@ -167,7 +167,7 @@ public function testSubQueryAnotherType()
         $this->assertSame('Developer', $jobs[0]->name);
     }
 
-    public function testWhereNullParam()
+    public function testWhereNullParam(): void
     {
         $this->db->table('job')
             ->insert([
@@ -184,7 +184,7 @@ public function testWhereNullParam()
         $this->assertSame('Brewmaster', $jobs[0]->name);
     }
 
-    public function testWhereIsNull()
+    public function testWhereIsNull(): void
     {
         $this->db->table('job')
             ->insert([
@@ -201,7 +201,7 @@ public function testWhereIsNull()
         $this->assertSame('Brewmaster', $jobs[0]->name);
     }
 
-    public function testWhereIsNotNull()
+    public function testWhereIsNotNull(): void
     {
         $this->db->table('job')
             ->insert([
@@ -220,7 +220,7 @@ public function testWhereIsNotNull()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4443
      */
-    public function testWhereWithLower()
+    public function testWhereWithLower(): void
     {
         $builder = $this->db->table('job');
         $builder->insert([
diff --git a/tests/system/Database/Live/WriteTypeQueryTest.php b/tests/system/Database/Live/WriteTypeQueryTest.php
index 19ca62ae3b06..9228288ac22d 100644
--- a/tests/system/Database/Live/WriteTypeQueryTest.php
+++ b/tests/system/Database/Live/WriteTypeQueryTest.php
@@ -28,14 +28,14 @@ final class WriteTypeQueryTest extends CIUnitTestCase
     protected $refresh = true;
     protected $seed    = CITestSeeder::class;
 
-    public function testSet()
+    public function testSet(): void
     {
         $sql = 'SET FOREIGN_KEY_CHECKS=0';
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testInsert()
+    public function testInsert(): void
     {
         $builder = $this->db->table('jobs');
 
@@ -55,7 +55,7 @@ public function testInsert()
         }
     }
 
-    public function testUpdate()
+    public function testUpdate(): void
     {
         $builder = new BaseBuilder('jobs', $this->db);
         $builder->testMode()->where('id', 1)->update(['name' => 'Programmer'], null, null);
@@ -70,7 +70,7 @@ public function testUpdate()
         }
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $builder = $this->db->table('jobs');
         $sql     = $builder->testMode()->delete(['id' => 1], null, true);
@@ -78,7 +78,7 @@ public function testDelete()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testReplace()
+    public function testReplace(): void
     {
         if (in_array($this->db->DBDriver, ['Postgre', 'SQLSRV'], true)) {
             // these two were complaining about the builder stuff so i just cooked up this
@@ -96,14 +96,14 @@ public function testReplace()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testCreate()
+    public function testCreate(): void
     {
         $sql = 'CREATE DATABASE foo';
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testDrop()
+    public function testDrop(): void
     {
         $sql = 'DROP DATABASE foo';
 
@@ -114,7 +114,7 @@ public function testDrop()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testTruncate()
+    public function testTruncate(): void
     {
         $builder = new BaseBuilder('user', $this->db);
         $sql     = $builder->testMode()->truncate();
@@ -122,28 +122,28 @@ public function testTruncate()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testLoad()
+    public function testLoad(): void
     {
         $sql = "LOAD DATA INFILE '/tmp/test.txt' INTO TABLE test FIELDS TERMINATED BY ','  LINES STARTING BY 'xxx';";
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testCopy()
+    public function testCopy(): void
     {
         $sql = "COPY demo(firstname, lastname) TO 'demo.txt' DELIMITER ' ';";
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testAlter()
+    public function testAlter(): void
     {
         $sql = 'ALTER TABLE supplier ADD supplier_name char(50);';
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testRename()
+    public function testRename(): void
     {
         if ($this->db->DBDriver === 'SQLSRV') {
             $sql = 'EXEC sp_rename table1 , table2 ;';
@@ -156,28 +156,28 @@ public function testRename()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testGrant()
+    public function testGrant(): void
     {
         $sql = 'GRANT SELECT ON TABLE my_table TO user1,user2';
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testRevoke()
+    public function testRevoke(): void
     {
         $sql = 'REVOKE SELECT ON TABLE my_table FROM user1,user2';
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testLock()
+    public function testLock(): void
     {
         $sql = 'LOCK TABLE my_table IN SHARE MODE;';
 
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testUnlock()
+    public function testUnlock(): void
     {
         // i think this is only a valid command for MySQL?
         $sql = 'UNLOCK TABLES;';
@@ -185,7 +185,7 @@ public function testUnlock()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testReindex()
+    public function testReindex(): void
     {
         // i think this is only a valid command for Postgre?
         $sql = 'REINDEX TABLE foo';
@@ -193,7 +193,7 @@ public function testReindex()
         $this->assertTrue($this->db->isWriteType($sql));
     }
 
-    public function testSelect()
+    public function testSelect(): void
     {
         $builder = new BaseBuilder('users', $this->db);
         $builder->select('*');
@@ -202,7 +202,7 @@ public function testSelect()
         $this->assertFalse($this->db->isWriteType($sql));
     }
 
-    public function testTrick()
+    public function testTrick(): void
     {
         $builder = new BaseBuilder('users', $this->db);
         $builder->select('UPDATE');
diff --git a/tests/system/Database/Migrations/MigrationRunnerTest.php b/tests/system/Database/Migrations/MigrationRunnerTest.php
index a9fa0171c104..6d88cd894e0d 100644
--- a/tests/system/Database/Migrations/MigrationRunnerTest.php
+++ b/tests/system/Database/Migrations/MigrationRunnerTest.php
@@ -55,7 +55,7 @@ protected function setUp(): void
         $this->config->enabled = true;
     }
 
-    protected function setUpAddNamespace()
+    protected function setUpAddNamespace(): void
     {
         Services::autoloader()->addNamespace(
             'Tests\Support\MigrationTestMigrations',
@@ -72,7 +72,7 @@ protected function tearDown(): void
         $this->regressDatabase();
     }
 
-    public function testLoadsDefaultDatabaseWhenNoneSpecified()
+    public function testLoadsDefaultDatabaseWhenNoneSpecified(): void
     {
         $dbConfig = new Database();
         $runner   = new MigrationRunner($this->config);
@@ -92,7 +92,7 @@ public function testLoadsDefaultDatabaseWhenNoneSpecified()
         $this->assertSame($dbConfig->tests['DBDriver'], $this->getPrivateProperty($db, 'DBDriver'));
     }
 
-    public function testGetCliMessages()
+    public function testGetCliMessages(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -103,7 +103,7 @@ public function testGetCliMessages()
         $this->assertSame($messages, $runner->getCliMessages());
     }
 
-    public function testGetHistory()
+    public function testGetHistory(): void
     {
         $runner = new MigrationRunner($this->config);
         $runner->ensureTable();
@@ -142,7 +142,7 @@ public function testGetHistory()
         }
     }
 
-    public function testGetHistoryReturnsEmptyArrayWithNoResults()
+    public function testGetHistoryReturnsEmptyArrayWithNoResults(): void
     {
         $runner = new MigrationRunner($this->config);
         $runner->ensureTable();
@@ -150,7 +150,7 @@ public function testGetHistoryReturnsEmptyArrayWithNoResults()
         $this->assertSame([], $runner->getHistory());
     }
 
-    public function testGetMigrationNumberAllDigits()
+    public function testGetMigrationNumberAllDigits(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -159,7 +159,7 @@ public function testGetMigrationNumberAllDigits()
         $this->assertSame('20190806235100', $method('20190806235100_Foo'));
     }
 
-    public function testGetMigrationNumberDashes()
+    public function testGetMigrationNumberDashes(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -168,7 +168,7 @@ public function testGetMigrationNumberDashes()
         $this->assertSame('2019-08-06-235100', $method('2019-08-06-235100_Foo'));
     }
 
-    public function testGetMigrationNumberUnderscores()
+    public function testGetMigrationNumberUnderscores(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -177,7 +177,7 @@ public function testGetMigrationNumberUnderscores()
         $this->assertSame('2019_08_06_235100', $method('2019_08_06_235100_Foo'));
     }
 
-    public function testGetMigrationNumberReturnsZeroIfNoneFound()
+    public function testGetMigrationNumberReturnsZeroIfNoneFound(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -186,7 +186,7 @@ public function testGetMigrationNumberReturnsZeroIfNoneFound()
         $this->assertSame('0', $method('Foo'));
     }
 
-    public function testGetMigrationNameDashes()
+    public function testGetMigrationNameDashes(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -195,7 +195,7 @@ public function testGetMigrationNameDashes()
         $this->assertSame('Foo_bar', $method('2019-08-06-235100_Foo_bar'));
     }
 
-    public function testGetMigrationNameUnderscores()
+    public function testGetMigrationNameUnderscores(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -204,7 +204,7 @@ public function testGetMigrationNameUnderscores()
         $this->assertSame('Foo_bar', $method('2019_08_06_235100_Foo_bar'));
     }
 
-    public function testSetSilentStoresValue()
+    public function testSetSilentStoresValue(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -215,7 +215,7 @@ public function testSetSilentStoresValue()
         $this->assertFalse($this->getPrivateProperty($runner, 'silent'));
     }
 
-    public function testSetNameStoresValue()
+    public function testSetNameStoresValue(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -223,7 +223,7 @@ public function testSetNameStoresValue()
         $this->assertSame('foo', $this->getPrivateProperty($runner, 'name'));
     }
 
-    public function testSetGroupStoresValue()
+    public function testSetGroupStoresValue(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -231,7 +231,7 @@ public function testSetGroupStoresValue()
         $this->assertSame('foo', $this->getPrivateProperty($runner, 'group'));
     }
 
-    public function testSetNamespaceStoresValue()
+    public function testSetNamespaceStoresValue(): void
     {
         $runner = new MigrationRunner($this->config);
 
@@ -239,7 +239,7 @@ public function testSetNamespaceStoresValue()
         $this->assertSame('foo', $this->getPrivateProperty($runner, 'namespace'));
     }
 
-    public function testFindMigrationsReturnsEmptyArrayWithNoneFound()
+    public function testFindMigrationsReturnsEmptyArrayWithNoneFound(): void
     {
         $config = $this->config;
         $runner = new MigrationRunner($config);
@@ -247,7 +247,7 @@ public function testFindMigrationsReturnsEmptyArrayWithNoneFound()
         $this->assertSame([], $runner->findMigrations());
     }
 
-    public function testFindMigrationsSuccessTimestamp()
+    public function testFindMigrationsSuccessTimestamp(): void
     {
         $config = $this->config;
         $runner = new MigrationRunner($config);
@@ -280,7 +280,7 @@ public function testFindMigrationsSuccessTimestamp()
         $this->assertSame((array) $mig2, (array) array_shift($migrations));
     }
 
-    public function testMigrationThrowsDisabledException()
+    public function testMigrationThrowsDisabledException(): void
     {
         $this->expectException(ConfigException::class);
         $this->expectExceptionMessage('Migrations have been loaded but are disabled or setup incorrectly.');
@@ -304,7 +304,7 @@ public function testMigrationThrowsDisabledException()
         $runner->latest();
     }
 
-    public function testVersionReturnsUpDownSuccess()
+    public function testVersionReturnsUpDownSuccess(): void
     {
         $forge = Database::forge();
         $forge->dropTable('foo', true);
@@ -329,7 +329,7 @@ public function testVersionReturnsUpDownSuccess()
         $this->assertFalse($this->db->tableExists('foo'));
     }
 
-    public function testLatestSuccess()
+    public function testLatestSuccess(): void
     {
         $runner = new MigrationRunner($this->config);
         $runner->setSilent(false)
@@ -347,7 +347,7 @@ public function testLatestSuccess()
         ]);
     }
 
-    public function testRegressSuccess()
+    public function testRegressSuccess(): void
     {
         $forge = Database::forge();
         $forge->dropTable('foo', true);
@@ -369,7 +369,7 @@ public function testRegressSuccess()
         $this->assertEmpty($history);
     }
 
-    public function testLatestTriggersEvent()
+    public function testLatestTriggersEvent(): void
     {
         $forge = Database::forge();
         $forge->dropTable('foo', true);
@@ -381,7 +381,7 @@ public function testLatestTriggersEvent()
         $result = null;
 
         Events::removeAllListeners();
-        Events::on('migrate', static function ($arg) use (&$result) {
+        Events::on('migrate', static function ($arg) use (&$result): void {
             $result = $arg;
         });
 
@@ -391,7 +391,7 @@ public function testLatestTriggersEvent()
         $this->assertSame('latest', $result['method']);
     }
 
-    public function testRegressTriggersEvent()
+    public function testRegressTriggersEvent(): void
     {
         $forge = Database::forge();
         $forge->dropTable('foo', true);
@@ -402,7 +402,7 @@ public function testRegressTriggersEvent()
 
         $result = null;
         Events::removeAllListeners();
-        Events::on('migrate', static function ($arg) use (&$result) {
+        Events::on('migrate', static function ($arg) use (&$result): void {
             $result = $arg;
         });
 
@@ -413,7 +413,7 @@ public function testRegressTriggersEvent()
         $this->assertSame('regress', $result['method']);
     }
 
-    public function testHistoryRecordsBatches()
+    public function testHistoryRecordsBatches(): void
     {
         $config = $this->config;
         $runner = new MigrationRunner($config);
@@ -436,7 +436,7 @@ public function testHistoryRecordsBatches()
         $this->seeInDatabase('migrations', ['batch' => 1]);
     }
 
-    public function testGetBatchVersions()
+    public function testGetBatchVersions(): void
     {
         $config = $this->config;
         $runner = new MigrationRunner($config);
@@ -452,7 +452,7 @@ public function testGetBatchVersions()
         $this->assertSame('2018-01-24-102302', $runner->getBatchEnd(1));
     }
 
-    protected function resetTables()
+    protected function resetTables(): void
     {
         $forge = Config::forge();
 
diff --git a/tests/system/Database/Migrations/MigrationTest.php b/tests/system/Database/Migrations/MigrationTest.php
index 97431a8c4fe8..ec1802212bb1 100644
--- a/tests/system/Database/Migrations/MigrationTest.php
+++ b/tests/system/Database/Migrations/MigrationTest.php
@@ -29,16 +29,16 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    public function testDBGroup()
+    public function testDBGroup(): void
     {
         $migration = new class () extends Migration {
             protected $DBGroup = 'tests';
 
-            public function up()
+            public function up(): void
             {
             }
 
-            public function down()
+            public function down(): void
             {
             }
         };
diff --git a/tests/system/Database/ModelFactoryTest.php b/tests/system/Database/ModelFactoryTest.php
index 4ec47a9b5967..58cc77f30891 100644
--- a/tests/system/Database/ModelFactoryTest.php
+++ b/tests/system/Database/ModelFactoryTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void
         ModelFactory::reset();
     }
 
-    public function testCreateSeparateInstances()
+    public function testCreateSeparateInstances(): void
     {
         $basenameModel  = ModelFactory::get('JobModel', false);
         $namespaceModel = ModelFactory::get(JobModel::class, false);
@@ -42,7 +42,7 @@ public function testCreateSeparateInstances()
         $this->assertNotSame($basenameModel, $namespaceModel);
     }
 
-    public function testCreateSharedInstance()
+    public function testCreateSharedInstance(): void
     {
         $basenameModel  = ModelFactory::get('JobModel', true);
         $namespaceModel = ModelFactory::get(JobModel::class, true);
@@ -50,14 +50,14 @@ public function testCreateSharedInstance()
         $this->assertSame($basenameModel, $namespaceModel);
     }
 
-    public function testInjection()
+    public function testInjection(): void
     {
         ModelFactory::injectMock('Banana', new JobModel());
 
         $this->assertInstanceOf(JobModel::class, ModelFactory::get('Banana'));
     }
 
-    public function testReset()
+    public function testReset(): void
     {
         ModelFactory::injectMock('Banana', new JobModel());
 
@@ -66,7 +66,7 @@ public function testReset()
         $this->assertNull(ModelFactory::get('Banana'));
     }
 
-    public function testBasenameReturnsExistingNamespaceInstance()
+    public function testBasenameReturnsExistingNamespaceInstance(): void
     {
         ModelFactory::injectMock(UserModel::class, new JobModel());
 
diff --git a/tests/system/Database/RawSqlTest.php b/tests/system/Database/RawSqlTest.php
index 695a63980e89..f60a4867f0cb 100644
--- a/tests/system/Database/RawSqlTest.php
+++ b/tests/system/Database/RawSqlTest.php
@@ -20,7 +20,7 @@
  */
 final class RawSqlTest extends CIUnitTestCase
 {
-    public function testCanConvertToString()
+    public function testCanConvertToString(): void
     {
         $expected = 'REGEXP_SUBSTR(ral_anno,"[0-9]{1,2}([,.][0-9]{1,3})([,.][0-9]{1,3})") AS ral';
         $rawSql   = new RawSql($expected);
@@ -28,7 +28,7 @@ public function testCanConvertToString()
         $this->assertSame($expected, (string) $rawSql);
     }
 
-    public function testCanCreateNewObject()
+    public function testCanCreateNewObject(): void
     {
         $firstSql = 'a = 1 AND b = 2';
         $rawSql   = new RawSql($firstSql);
@@ -40,7 +40,7 @@ public function testCanCreateNewObject()
         $this->assertSame($secondSql, (string) $newRawSQL);
     }
 
-    public function testGetBindingKey()
+    public function testGetBindingKey(): void
     {
         $firstSql = 'a = 1 AND b = 2';
         $rawSql   = new RawSql($firstSql);
diff --git a/tests/system/Debug/TimerTest.php b/tests/system/Debug/TimerTest.php
index cbab2c82002c..d99d877fc84a 100644
--- a/tests/system/Debug/TimerTest.php
+++ b/tests/system/Debug/TimerTest.php
@@ -30,7 +30,7 @@ final class TimerTest extends CIUnitTestCase
      *
      * @timeLimit 1.5
      */
-    public function testStoresTimers()
+    public function testStoresTimers(): void
     {
         $timer = new Timer();
 
@@ -54,7 +54,7 @@ public function testStoresTimers()
     /**
      * @timeLimit 1.5
      */
-    public function testAutoCalcsTimerEnd()
+    public function testAutoCalcsTimerEnd(): void
     {
         $timer = new Timer();
 
@@ -70,7 +70,7 @@ public function testAutoCalcsTimerEnd()
     /**
      * @timeLimit 1.5
      */
-    public function testElapsedTimeGivesSameResultAsTimersArray()
+    public function testElapsedTimeGivesSameResultAsTimersArray(): void
     {
         $timer = new Timer();
 
@@ -85,7 +85,7 @@ public function testElapsedTimeGivesSameResultAsTimersArray()
         $this->assertSame($expected, $timer->getElapsedTime('test1'));
     }
 
-    public function testThrowsExceptionStoppingNonTimer()
+    public function testThrowsExceptionStoppingNonTimer(): void
     {
         $this->expectException('RunTimeException');
 
@@ -98,14 +98,14 @@ public function testThrowsExceptionStoppingNonTimer()
      * This test might fail if your timezone has Daylight Saving Time.
      * See https://github.com/codeigniter4/CodeIgniter4/issues/6823
      */
-    public function testLongExecutionTime()
+    public function testLongExecutionTime(): void
     {
         $timer = new Timer();
         $timer->start('longjohn', strtotime('-110 minutes'));
         $this->assertCloseEnough(110 * 60, $timer->getElapsedTime('longjohn'));
     }
 
-    public function testLongExecutionTimeThroughCommonFunc()
+    public function testLongExecutionTimeThroughCommonFunc(): void
     {
         $timer = new Timer();
         $timer->start('longjohn', strtotime('-11 minutes'));
@@ -115,7 +115,7 @@ public function testLongExecutionTimeThroughCommonFunc()
     /**
      * @timeLimit 1.5
      */
-    public function testCommonStartStop()
+    public function testCommonStartStop(): void
     {
         timer('test1');
         sleep(1);
@@ -124,23 +124,23 @@ public function testCommonStartStop()
         $this->assertGreaterThanOrEqual(1.0, timer()->getElapsedTime('test1'));
     }
 
-    public function testReturnsNullGettingElapsedTimeOfNonTimer()
+    public function testReturnsNullGettingElapsedTimeOfNonTimer(): void
     {
         $timer = new Timer();
 
         $this->assertNull($timer->getElapsedTime('test1'));
     }
 
-    public function testRecordFunctionNoReturn()
+    public function testRecordFunctionNoReturn(): void
     {
         $timer       = new Timer();
-        $returnValue = $timer->record('longjohn', static function () { usleep(100000); });
+        $returnValue = $timer->record('longjohn', static function (): void { usleep(100000); });
 
         $this->assertGreaterThanOrEqual(0.1, $timer->getElapsedTime('longjohn'));
         $this->assertNull($returnValue);
     }
 
-    public function testRecordFunctionWithReturn()
+    public function testRecordFunctionWithReturn(): void
     {
         $timer       = new Timer();
         $returnValue = $timer->record('longjohn', static function () {
@@ -153,7 +153,7 @@ public function testRecordFunctionWithReturn()
         $this->assertSame('test', $returnValue);
     }
 
-    public function testRecordArrowFunction()
+    public function testRecordArrowFunction(): void
     {
         $timer       = new Timer();
         $returnValue = $timer->record('longjohn', static fn () => strlen('CI4'));
@@ -162,15 +162,15 @@ public function testRecordArrowFunction()
         $this->assertSame(3, $returnValue);
     }
 
-    public function testRecordThrowsException()
+    public function testRecordThrowsException(): void
     {
         $this->expectException(RuntimeException::class);
 
         $timer = new Timer();
-        $timer->record('ex', static function () { throw new RuntimeException(); });
+        $timer->record('ex', static function (): void { throw new RuntimeException(); });
     }
 
-    public function testRecordThrowsErrorOnCallableWithParams()
+    public function testRecordThrowsErrorOnCallableWithParams(): void
     {
         if (version_compare(PHP_VERSION, '8.0.0') >= 0) {
             $this->expectException(ArgumentCountError::class);
@@ -182,14 +182,14 @@ public function testRecordThrowsErrorOnCallableWithParams()
         $timer->record('error', 'strlen');
     }
 
-    public function testCommonNoNameExpectTimer()
+    public function testCommonNoNameExpectTimer(): void
     {
         $returnValue = timer();
 
         $this->assertInstanceOf(Timer::class, $returnValue);
     }
 
-    public function testCommonWithNameExpectTimer()
+    public function testCommonWithNameExpectTimer(): void
     {
         $returnValue = timer('test');
 
@@ -197,23 +197,23 @@ public function testCommonWithNameExpectTimer()
         $this->assertTrue($returnValue->has('test'));
     }
 
-    public function testCommonNoNameCallableExpectTimer()
+    public function testCommonNoNameCallableExpectTimer(): void
     {
         $returnValue = timer(null, static fn () => strlen('CI4'));
 
         $this->assertInstanceOf(Timer::class, $returnValue);
     }
 
-    public function testCommonCallableExpectNoReturn()
+    public function testCommonCallableExpectNoReturn(): void
     {
-        $returnValue = timer('common', static function () { usleep(100000); });
+        $returnValue = timer('common', static function (): void { usleep(100000); });
 
         $this->assertNotInstanceOf(Timer::class, $returnValue);
         $this->assertNull($returnValue);
         $this->assertGreaterThanOrEqual(0.1, timer()->getElapsedTime('common'));
     }
 
-    public function testCommonCallableExpectWithReturn()
+    public function testCommonCallableExpectWithReturn(): void
     {
         $returnValue = timer('common', static fn () => strlen('CI4'));
 
diff --git a/tests/system/Debug/Toolbar/Collectors/HistoryTest.php b/tests/system/Debug/Toolbar/Collectors/HistoryTest.php
index ab9aa9c38db3..1286a489b14f 100644
--- a/tests/system/Debug/Toolbar/Collectors/HistoryTest.php
+++ b/tests/system/Debug/Toolbar/Collectors/HistoryTest.php
@@ -42,7 +42,7 @@ protected function tearDown(): void
         parent::tearDown();
     }
 
-    private function createDummyDebugbarJson()
+    private function createDummyDebugbarJson(): void
     {
         $time = $this->time;
         $path = WRITEPATH . 'debugbar' . DIRECTORY_SEPARATOR . "debugbar_{$time}.json";
@@ -67,7 +67,7 @@ private function createDummyDebugbarJson()
         }
     }
 
-    public function testSetFiles()
+    public function testSetFiles(): void
     {
         $time = $this->time;
 
diff --git a/tests/system/Email/EmailTest.php b/tests/system/Email/EmailTest.php
index cff60c7f9e0b..2fff192e7295 100644
--- a/tests/system/Email/EmailTest.php
+++ b/tests/system/Email/EmailTest.php
@@ -23,7 +23,7 @@
  */
 final class EmailTest extends CIUnitTestCase
 {
-    public function testEmailValidation()
+    public function testEmailValidation(): void
     {
         $config           = config('Email');
         $config->validate = true;
@@ -45,7 +45,7 @@ public function autoClearProvider(): iterable
      *
      * @param mixed $autoClear
      */
-    public function testEmailSendWithClearance($autoClear)
+    public function testEmailSendWithClearance($autoClear): void
     {
         $email = $this->createMockEmail();
 
@@ -58,7 +58,7 @@ public function testEmailSendWithClearance($autoClear)
         }
     }
 
-    public function testEmailSendStoresArchive()
+    public function testEmailSendStoresArchive(): void
     {
         $email = $this->createMockEmail();
 
@@ -74,7 +74,7 @@ public function testEmailSendStoresArchive()
         $this->assertSame('Archive Test', $email->archive['subject']);
     }
 
-    public function testAutoClearLeavesArchive()
+    public function testAutoClearLeavesArchive(): void
     {
         $email = $this->createMockEmail();
 
@@ -85,7 +85,7 @@ public function testAutoClearLeavesArchive()
         $this->assertNotEmpty($email->archive);
     }
 
-    public function testEmailSendRepeatUpdatesArchive()
+    public function testEmailSendRepeatUpdatesArchive(): void
     {
         $config = config('Email');
         $email  = new MockEmail($config);
@@ -103,7 +103,7 @@ public function testEmailSendRepeatUpdatesArchive()
         $this->assertSame('Archive Test', $email->archive['subject']);
     }
 
-    public function testSuccessDoesTriggerEvent()
+    public function testSuccessDoesTriggerEvent(): void
     {
         $email = $this->createMockEmail();
 
@@ -111,7 +111,7 @@ public function testSuccessDoesTriggerEvent()
 
         $result = null;
 
-        Events::on('email', static function ($arg) use (&$result) {
+        Events::on('email', static function ($arg) use (&$result): void {
             $result = $arg;
         });
 
@@ -121,7 +121,7 @@ public function testSuccessDoesTriggerEvent()
         $this->assertSame(['foo@foo.com'], $result['recipients']);
     }
 
-    public function testFailureDoesNotTriggerEvent()
+    public function testFailureDoesNotTriggerEvent(): void
     {
         $email = $this->createMockEmail();
 
@@ -130,7 +130,7 @@ public function testFailureDoesNotTriggerEvent()
 
         $result = null;
 
-        Events::on('email', static function ($arg) use (&$result) {
+        Events::on('email', static function ($arg) use (&$result): void {
             $result = $arg;
         });
 
@@ -139,7 +139,7 @@ public function testFailureDoesNotTriggerEvent()
         $this->assertNull($result);
     }
 
-    public function testDestructDoesNotThrowException()
+    public function testDestructDoesNotThrowException(): void
     {
         $email = $this->getMockBuilder(Email::class)
             ->disableOriginalConstructor()
diff --git a/tests/system/Encryption/EncryptionTest.php b/tests/system/Encryption/EncryptionTest.php
index cbdccd2fbbe1..9ab09dc77216 100644
--- a/tests/system/Encryption/EncryptionTest.php
+++ b/tests/system/Encryption/EncryptionTest.php
@@ -35,7 +35,7 @@ protected function setUp(): void
      *
      * Covers behavior with config encryption key set or not
      */
-    public function testConstructor()
+    public function testConstructor(): void
     {
         // Assume no configuration from set_up()
         $this->assertEmpty($this->encryption->key);
@@ -55,7 +55,7 @@ public function testConstructor()
     /**
      * Covers behavior with invalid parameters
      */
-    public function testBadDriver()
+    public function testBadDriver(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -70,7 +70,7 @@ public function testBadDriver()
     /**
      * Covers behavior with invalid parameters
      */
-    public function testMissingDriver()
+    public function testMissingDriver(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -82,14 +82,14 @@ public function testMissingDriver()
         $this->encryption->initialize($config);
     }
 
-    public function testKeyCreation()
+    public function testKeyCreation(): void
     {
         $this->assertNotEmpty($this->encryption->createKey());
         $this->assertSame(32, strlen($this->encryption->createKey()));
         $this->assertSame(16, strlen($this->encryption->createKey(16)));
     }
 
-    public function testServiceSuccess()
+    public function testServiceSuccess(): void
     {
         $config         = new EncryptionConfig();
         $config->driver = 'OpenSSL';
@@ -99,7 +99,7 @@ public function testServiceSuccess()
         $this->assertInstanceOf(EncrypterInterface::class, $encrypter);
     }
 
-    public function testServiceFailure()
+    public function testServiceFailure(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -111,14 +111,14 @@ public function testServiceFailure()
         Services::encrypter($config);
     }
 
-    public function testServiceWithoutKey()
+    public function testServiceWithoutKey(): void
     {
         $this->expectException(EncryptionException::class);
 
         Services::encrypter();
     }
 
-    public function testServiceShared()
+    public function testServiceShared(): void
     {
         $config         = new EncryptionConfig();
         $config->driver = 'OpenSSL';
@@ -131,27 +131,27 @@ public function testServiceShared()
         $this->assertSame('anything', $encrypter->key);
     }
 
-    public function testMagicIssetTrue()
+    public function testMagicIssetTrue(): void
     {
         $this->assertTrue(isset($this->encryption->digest));
     }
 
-    public function testMagicIssetFalse()
+    public function testMagicIssetFalse(): void
     {
         $this->assertFalse(isset($this->encryption->bogus));
     }
 
-    public function testMagicGet()
+    public function testMagicGet(): void
     {
         $this->assertSame('SHA512', $this->encryption->digest);
     }
 
-    public function testMagicGetMissing()
+    public function testMagicGetMissing(): void
     {
         $this->assertNull($this->encryption->bogus);
     }
 
-    public function testDecryptEncryptedDataByCI3AES128CBC()
+    public function testDecryptEncryptedDataByCI3AES128CBC(): void
     {
         $config                 = new EncryptionConfig();
         $config->driver         = 'OpenSSL';
@@ -169,7 +169,7 @@ public function testDecryptEncryptedDataByCI3AES128CBC()
         $this->assertSame($expected, $decrypted);
     }
 
-    public function testDecryptEncryptedDataByCI3AES256CTR()
+    public function testDecryptEncryptedDataByCI3AES256CTR(): void
     {
         $config                 = new EncryptionConfig();
         $config->driver         = 'OpenSSL';
@@ -186,7 +186,7 @@ public function testDecryptEncryptedDataByCI3AES256CTR()
         $this->assertSame($expected, $decrypted);
     }
 
-    public function testDecryptEncryptedDataByCI42()
+    public function testDecryptEncryptedDataByCI42(): void
     {
         $config      = new EncryptionConfig();
         $config->key = hex2bin('64c70b0b8d45b80b9eba60b8b3c8a34d0193223d20fea46f8644b848bf7ce67f');
diff --git a/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php b/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php
index 233221da2af3..6773670f43c3 100644
--- a/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php
+++ b/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php
@@ -37,7 +37,7 @@ protected function setUp(): void
     /**
      * Sanity test
      */
-    public function testSanity()
+    public function testSanity(): void
     {
         $params         = new EncryptionConfig();
         $params->driver = 'OpenSSL';
@@ -55,7 +55,7 @@ public function testSanity()
      * Testing the three methods separately is not realistic as they are
      * designed to work together.
      */
-    public function testSimple()
+    public function testSimple(): void
     {
         $params         = new EncryptionConfig();
         $params->driver = 'OpenSSL';
@@ -77,7 +77,7 @@ public function testSimple()
     /**
      * Starter key needed
      */
-    public function testWithoutKey()
+    public function testWithoutKey(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -86,7 +86,7 @@ public function testWithoutKey()
         $encrypter->encrypt($message1, ['key' => '']);
     }
 
-    public function testWithKeyString()
+    public function testWithKeyString(): void
     {
         $key       = 'abracadabra';
         $encrypter = new OpenSSLHandler();
@@ -98,7 +98,7 @@ public function testWithKeyString()
     /**
      * Authentication will fail decrypting with the wrong key
      */
-    public function testWithWrongKeyString()
+    public function testWithWrongKeyString(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -111,7 +111,7 @@ public function testWithWrongKeyString()
         $this->assertNotSame($message1, $encrypter->decrypt($encoded, $key2));
     }
 
-    public function testWithKeyArray()
+    public function testWithKeyArray(): void
     {
         $key       = 'abracadabra';
         $encrypter = new OpenSSLHandler();
@@ -123,7 +123,7 @@ public function testWithKeyArray()
     /**
      * Authentication will fail decrypting with the wrong key
      */
-    public function testWithWrongKeyArray()
+    public function testWithWrongKeyArray(): void
     {
         $this->expectException(EncryptionException::class);
 
diff --git a/tests/system/Encryption/Handlers/SodiumHandlerTest.php b/tests/system/Encryption/Handlers/SodiumHandlerTest.php
index 9801625c1524..32b66fc041a2 100644
--- a/tests/system/Encryption/Handlers/SodiumHandlerTest.php
+++ b/tests/system/Encryption/Handlers/SodiumHandlerTest.php
@@ -40,7 +40,7 @@ protected function setUp(): void
         $this->encryption     = new Encryption($this->config);
     }
 
-    public function testPropertiesGetter()
+    public function testPropertiesGetter(): void
     {
         $this->config->key       = sodium_crypto_secretbox_keygen();
         $this->config->blockSize = 256;
@@ -51,7 +51,7 @@ public function testPropertiesGetter()
         $this->assertNull($encrypter->driver);
     }
 
-    public function testEmptyKeyThrowsErrorOnInitialize()
+    public function testEmptyKeyThrowsErrorOnInitialize(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -59,7 +59,7 @@ public function testEmptyKeyThrowsErrorOnInitialize()
         $this->encryption->initialize($this->config);
     }
 
-    public function testEmptyKeyThrowsErrorOnEncrypt()
+    public function testEmptyKeyThrowsErrorOnEncrypt(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -67,7 +67,7 @@ public function testEmptyKeyThrowsErrorOnEncrypt()
         $encrypter->encrypt('Some message to encrypt', '');
     }
 
-    public function testInvalidBlockSizeThrowsErrorOnEncrypt()
+    public function testInvalidBlockSizeThrowsErrorOnEncrypt(): void
     {
         $this->expectException(EncryptionException::class);
         $this->config->blockSize = -1;
@@ -76,7 +76,7 @@ public function testInvalidBlockSizeThrowsErrorOnEncrypt()
         $encrypter->encrypt('Some message.');
     }
 
-    public function testEmptyKeyThrowsErrorOnDecrypt()
+    public function testEmptyKeyThrowsErrorOnDecrypt(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -86,7 +86,7 @@ public function testEmptyKeyThrowsErrorOnDecrypt()
         $encrypter->decrypt($ciphertext);
     }
 
-    public function testInvalidBlockSizeThrowsErrorOnDecrypt()
+    public function testInvalidBlockSizeThrowsErrorOnDecrypt(): void
     {
         $this->expectException(EncryptionException::class);
         $key = $this->config->key;
@@ -97,7 +97,7 @@ public function testInvalidBlockSizeThrowsErrorOnDecrypt()
         $encrypter->decrypt($ciphertext, ['key' => $key, 'blockSize' => 0]);
     }
 
-    public function testTruncatedMessageThrowsErrorOnDecrypt()
+    public function testTruncatedMessageThrowsErrorOnDecrypt(): void
     {
         $this->expectException(EncryptionException::class);
 
@@ -107,7 +107,7 @@ public function testTruncatedMessageThrowsErrorOnDecrypt()
         $encrypter->decrypt($truncated, ['blockSize' => 256, 'key' => sodium_crypto_secretbox_keygen()]);
     }
 
-    public function testDecryptingMessages()
+    public function testDecryptingMessages(): void
     {
         $key = sodium_crypto_secretbox_keygen();
         $msg = 'A plaintext message for you.';
diff --git a/tests/system/Entity/EntityTest.php b/tests/system/Entity/EntityTest.php
index 1e03157ab188..be3fb0db8d2e 100644
--- a/tests/system/Entity/EntityTest.php
+++ b/tests/system/Entity/EntityTest.php
@@ -34,7 +34,7 @@ final class EntityTest extends CIUnitTestCase
 {
     use ReflectionHelper;
 
-    public function testSimpleSetAndGet()
+    public function testSimpleSetAndGet(): void
     {
         $entity = $this->getEntity();
 
@@ -43,7 +43,7 @@ public function testSimpleSetAndGet()
         $this->assertSame('to wong', $entity->foo);
     }
 
-    public function testGetterSetters()
+    public function testGetterSetters(): void
     {
         $entity = $this->getEntity();
 
@@ -52,7 +52,7 @@ public function testGetterSetters()
         $this->assertSame('bar:thanks:bar', $entity->bar);
     }
 
-    public function testUnsetUnsetsAttribute()
+    public function testUnsetUnsetsAttribute(): void
     {
         $entity = $this->getEntity();
 
@@ -67,7 +67,7 @@ public function testUnsetUnsetsAttribute()
         $this->assertNull($entity->default);
     }
 
-    public function testIssetWorksLikeTraditionalIsset()
+    public function testIssetWorksLikeTraditionalIsset(): void
     {
         $entity = $this->getEntity();
 
@@ -84,7 +84,7 @@ public function testIssetWorksLikeTraditionalIsset()
         $this->assertTrue($issetDefaultReturn);
     }
 
-    public function testFill()
+    public function testFill(): void
     {
         $entity = $this->getEntity();
 
@@ -102,7 +102,7 @@ public function testFill()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1567
      */
-    public function testFillMapsEntities()
+    public function testFillMapsEntities(): void
     {
         $entity = $this->getMappedEntity();
 
@@ -116,7 +116,7 @@ public function testFillMapsEntities()
         $this->assertSame('oo:simple:oo', $entity->orig);
     }
 
-    public function testDataMappingConvertsOriginalName()
+    public function testDataMappingConvertsOriginalName(): void
     {
         $entity = $this->getMappedEntity();
 
@@ -134,7 +134,7 @@ public function testDataMappingConvertsOriginalName()
         $this->getPrivateProperty($entity, 'bar');
     }
 
-    public function testDataMappingWorksWithCustomSettersAndGetters()
+    public function testDataMappingWorksWithCustomSettersAndGetters(): void
     {
         $entity = $this->getMappedEntity();
 
@@ -148,7 +148,7 @@ public function testDataMappingWorksWithCustomSettersAndGetters()
         $this->assertSame('oo:second:oo', $entity->simple);
     }
 
-    public function testDataMappingIsset()
+    public function testDataMappingIsset(): void
     {
         $entity = $this->getMappedEntity();
 
@@ -162,7 +162,7 @@ public function testDataMappingIsset()
         $this->assertFalse($isset);
     }
 
-    public function testUnsetWorksWithMapping()
+    public function testUnsetWorksWithMapping(): void
     {
         $entity = $this->getMappedEntity();
 
@@ -184,7 +184,7 @@ public function testUnsetWorksWithMapping()
         $this->assertFalse($isset);
     }
 
-    public function testDateMutationFromString()
+    public function testDateMutationFromString(): void
     {
         $entity     = $this->getEntity();
         $attributes = ['created_at' => '2017-07-15 13:23:34'];
@@ -196,7 +196,7 @@ public function testDateMutationFromString()
         $this->assertSame('2017-07-15 13:23:34', $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationFromTimestamp()
+    public function testDateMutationFromTimestamp(): void
     {
         $stamp      = time();
         $entity     = $this->getEntity();
@@ -209,7 +209,7 @@ public function testDateMutationFromTimestamp()
         $this->assertCloseEnoughString(date('Y-m-d H:i:s', $stamp), $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationFromDatetime()
+    public function testDateMutationFromDatetime(): void
     {
         $dt         = new DateTime('now');
         $entity     = $this->getEntity();
@@ -222,7 +222,7 @@ public function testDateMutationFromDatetime()
         $this->assertCloseEnoughString($dt->format('Y-m-d H:i:s'), $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationFromTime()
+    public function testDateMutationFromTime(): void
     {
         $dt         = Time::now();
         $entity     = $this->getEntity();
@@ -235,7 +235,7 @@ public function testDateMutationFromTime()
         $this->assertCloseEnoughString($dt->format('Y-m-d H:i:s'), $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationStringToTime()
+    public function testDateMutationStringToTime(): void
     {
         $entity = $this->getEntity();
 
@@ -246,7 +246,7 @@ public function testDateMutationStringToTime()
         $this->assertSame('2017-07-15 13:23:34', $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationTimestampToTime()
+    public function testDateMutationTimestampToTime(): void
     {
         $stamp  = time();
         $entity = $this->getEntity();
@@ -258,7 +258,7 @@ public function testDateMutationTimestampToTime()
         $this->assertCloseEnoughString(date('Y-m-d H:i:s'), $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationDatetimeToTime()
+    public function testDateMutationDatetimeToTime(): void
     {
         $dt     = new DateTime('now');
         $entity = $this->getEntity();
@@ -270,7 +270,7 @@ public function testDateMutationDatetimeToTime()
         $this->assertCloseEnoughString($dt->format('Y-m-d H:i:s'), $time->format('Y-m-d H:i:s'));
     }
 
-    public function testDateMutationTimeToTime()
+    public function testDateMutationTimeToTime(): void
     {
         $dt     = Time::now();
         $entity = $this->getEntity();
@@ -282,7 +282,7 @@ public function testDateMutationTimeToTime()
         $this->assertCloseEnoughString($dt->format('Y-m-d H:i:s'), $time->format('Y-m-d H:i:s'));
     }
 
-    public function testCastInteger()
+    public function testCastInteger(): void
     {
         $entity = $this->getCastEntity();
 
@@ -296,7 +296,7 @@ public function testCastInteger()
         $this->assertSame(3, $entity->first);
     }
 
-    public function testCastIntBool()
+    public function testCastIntBool(): void
     {
         $entity = new class () extends Entity {
             protected $casts = [
@@ -323,7 +323,7 @@ public function testCastIntBool()
         $this->assertSame(['active' => 0], $entity->toRawArray());
     }
 
-    public function testCastFloat()
+    public function testCastFloat(): void
     {
         $entity = $this->getCastEntity();
 
@@ -338,7 +338,7 @@ public function testCastFloat()
         $this->assertSame(3.6, $entity->second);
     }
 
-    public function testCastDouble()
+    public function testCastDouble(): void
     {
         $entity = $this->getCastEntity();
 
@@ -353,7 +353,7 @@ public function testCastDouble()
         $this->assertSame(3.6, $entity->third);
     }
 
-    public function testCastString()
+    public function testCastString(): void
     {
         $entity = $this->getCastEntity();
 
@@ -363,7 +363,7 @@ public function testCastString()
         $this->assertSame('3.1415', $entity->fourth);
     }
 
-    public function testCastBoolean()
+    public function testCastBoolean(): void
     {
         $entity = $this->getCastEntity();
 
@@ -378,7 +378,7 @@ public function testCastBoolean()
         $this->assertFalse($entity->fifth);
     }
 
-    public function testCastCSV()
+    public function testCastCSV(): void
     {
         $entity          = $this->getCastEntity();
         $data            = ['foo', 'bar', 'bam'];
@@ -393,7 +393,7 @@ public function testCastCSV()
         $this->assertSame($data, $entity->twelfth);
     }
 
-    public function testCastObject()
+    public function testCastObject(): void
     {
         $entity = $this->getCastEntity();
 
@@ -405,7 +405,7 @@ public function testCastObject()
         $this->assertSame($data, (array) $entity->sixth);
     }
 
-    public function testCastDateTime()
+    public function testCastDateTime(): void
     {
         $entity = $this->getCastEntity();
 
@@ -415,7 +415,7 @@ public function testCastDateTime()
         $this->assertSame('2017-03-12', $entity->eighth->format('Y-m-d'));
     }
 
-    public function testCastTimestamp()
+    public function testCastTimestamp(): void
     {
         $entity = $this->getCastEntity();
 
@@ -426,7 +426,7 @@ public function testCastTimestamp()
         $this->assertSame(strtotime($date), $entity->ninth);
     }
 
-    public function testCastTimestampException()
+    public function testCastTimestampException(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Type casting "timestamp" expects a correct timestamp.');
@@ -437,7 +437,7 @@ public function testCastTimestampException()
         $entity->ninth;
     }
 
-    public function testCastArray()
+    public function testCastArray(): void
     {
         $entity = $this->getCastEntity();
 
@@ -448,7 +448,7 @@ public function testCastArray()
         $this->assertSame(['foo' => 'bar'], $entity->seventh);
     }
 
-    public function testCastArrayByStringSerialize()
+    public function testCastArrayByStringSerialize(): void
     {
         $entity = $this->getCastEntity();
 
@@ -461,7 +461,7 @@ public function testCastArrayByStringSerialize()
         $this->assertSame(['foobar'], $entity->seventh);
     }
 
-    public function testCastArrayByArraySerialize()
+    public function testCastArrayByArraySerialize(): void
     {
         $entity = $this->getCastEntity();
 
@@ -474,7 +474,7 @@ public function testCastArrayByArraySerialize()
         $this->assertSame(['foo' => 'bar'], $entity->seventh);
     }
 
-    public function testCastArrayByFill()
+    public function testCastArrayByFill(): void
     {
         $entity = $this->getCastEntity();
 
@@ -488,7 +488,7 @@ public function testCastArrayByFill()
         $this->assertSame([1, 2, 3], $entity->seventh);
     }
 
-    public function testCastArrayByConstructor()
+    public function testCastArrayByConstructor(): void
     {
         $data   = ['seventh' => [1, 2, 3]];
         $entity = $this->getCastEntity($data);
@@ -500,7 +500,7 @@ public function testCastArrayByConstructor()
         $this->assertSame([1, 2, 3], $entity->seventh);
     }
 
-    public function testCastNullable()
+    public function testCastNullable(): void
     {
         $entity = $this->getCastNullableEntity();
 
@@ -511,7 +511,7 @@ public function testCastNullable()
         $this->assertSame('value', $entity->string_value_not_null);
     }
 
-    public function testCastURI()
+    public function testCastURI(): void
     {
         $entity = $this->getCastEntity();
 
@@ -523,7 +523,7 @@ public function testCastURI()
         $this->assertSame('/banana', $entity->thirteenth->getPath());
     }
 
-    public function testURICastURI()
+    public function testURICastURI(): void
     {
         $entity = $this->getCastEntity();
 
@@ -535,7 +535,7 @@ public function testURICastURI()
         $this->assertSame('/banana', $entity->thirteenth->getPath());
     }
 
-    public function testCastAsJSON()
+    public function testCastAsJSON(): void
     {
         $entity = $this->getCastEntity();
 
@@ -549,7 +549,7 @@ public function testCastAsJSON()
         $this->assertSame(['foo' => 'bar'], (array) $entity->tenth);
     }
 
-    public function testCastAsJSONArray()
+    public function testCastAsJSONArray(): void
     {
         $entity = $this->getCastEntity();
 
@@ -563,7 +563,7 @@ public function testCastAsJSONArray()
         $this->assertSame($data, $entity->eleventh);
     }
 
-    public function testCastAsJsonByFill()
+    public function testCastAsJsonByFill(): void
     {
         $entity = $this->getCastEntity();
 
@@ -577,7 +577,7 @@ public function testCastAsJsonByFill()
         $this->assertSame([1, 2, 3], $entity->eleventh);
     }
 
-    public function testCastAsJsonByConstructor()
+    public function testCastAsJsonByConstructor(): void
     {
         $data   = ['eleventh' => [1, 2, 3]];
         $entity = $this->getCastEntity($data);
@@ -589,7 +589,7 @@ public function testCastAsJsonByConstructor()
         $this->assertSame([1, 2, 3], $entity->eleventh);
     }
 
-    public function testCastAsJSONErrorDepth()
+    public function testCastAsJSONErrorDepth(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Maximum stack depth exceeded');
@@ -610,7 +610,7 @@ public function testCastAsJSONErrorDepth()
         $entity->tenth = $array;
     }
 
-    public function testCastAsJSONErrorUTF8()
+    public function testCastAsJSONErrorUTF8(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Malformed UTF-8 characters, possibly incorrectly encoded');
@@ -623,7 +623,7 @@ public function testCastAsJSONErrorUTF8()
     /**
      * @psalm-suppress InaccessibleMethod
      */
-    public function testCastAsJSONSyntaxError()
+    public function testCastAsJSONSyntaxError(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Syntax error, malformed JSON');
@@ -639,7 +639,7 @@ public function testCastAsJSONSyntaxError()
     /**
      * @psalm-suppress InaccessibleMethod
      */
-    public function testCastAsJSONAnotherErrorDepth()
+    public function testCastAsJSONAnotherErrorDepth(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Maximum stack depth exceeded');
@@ -656,7 +656,7 @@ public function testCastAsJSONAnotherErrorDepth()
     /**
      * @psalm-suppress InaccessibleMethod
      */
-    public function testCastAsJSONControlCharCheck()
+    public function testCastAsJSONControlCharCheck(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Unexpected control character found');
@@ -673,7 +673,7 @@ public function testCastAsJSONControlCharCheck()
     /**
      * @psalm-suppress InaccessibleMethod
      */
-    public function testCastAsJSONStateMismatch()
+    public function testCastAsJSONStateMismatch(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('Underflow or the modes mismatch');
@@ -687,7 +687,7 @@ public function testCastAsJSONStateMismatch()
         }, null, Entity::class))($string);
     }
 
-    public function testCastSetter()
+    public function testCastSetter(): void
     {
         $string        = '321 String with numbers 123';
         $entity        = $this->getCastEntity();
@@ -704,14 +704,14 @@ public function testCastSetter()
         $this->assertSame((int) $string, $entity->first);
     }
 
-    public function testCastGetter()
+    public function testCastGetter(): void
     {
         $entity = new Entity();
 
         $this->assertIsBool($entity->cast());
     }
 
-    public function testCustomCast()
+    public function testCustomCast(): void
     {
         $entity = $this->getCustomCastEntity();
 
@@ -722,7 +722,7 @@ public function testCustomCast()
         $this->assertSame('base 64', $entity->first);
     }
 
-    public function testCustomCastException()
+    public function testCustomCastException(): void
     {
         $this->expectException(CastException::class);
         $this->expectExceptionMessage('The "Tests\Support\Entity\Cast\NotExtendsBaseCast" class must inherit the "CodeIgniter\Entity\Cast\BaseCast" class');
@@ -732,7 +732,7 @@ public function testCustomCastException()
         $entity->second = 'throw Exception';
     }
 
-    public function testCustomCastParams()
+    public function testCustomCastParams(): void
     {
         $entity = $this->getCustomCastEntity();
 
@@ -745,7 +745,7 @@ public function testCustomCastParams()
         $this->assertSame('test_nullable_type:["nullable"]', $entity->fourth);
     }
 
-    public function testAsArray()
+    public function testAsArray(): void
     {
         $entity = $this->getEntity();
 
@@ -759,7 +759,7 @@ public function testAsArray()
         ], $result, );
     }
 
-    public function testAsArrayRecursive()
+    public function testAsArrayRecursive(): void
     {
         $entity         = $this->getEntity();
         $entity->entity = $this->getEntity();
@@ -780,7 +780,7 @@ public function testAsArrayRecursive()
         ], $result);
     }
 
-    public function testAsArrayMapped()
+    public function testAsArrayMapped(): void
     {
         $entity = $this->getMappedEntity();
 
@@ -792,7 +792,7 @@ public function testAsArrayMapped()
         ], $result);
     }
 
-    public function testAsArraySwapped()
+    public function testAsArraySwapped(): void
     {
         $entity = $this->getSwappedEntity();
 
@@ -805,7 +805,7 @@ public function testAsArraySwapped()
         ], $result);
     }
 
-    public function testDataMappingIssetSwapped()
+    public function testDataMappingIssetSwapped(): void
     {
         $entity = $this->getSimpleSwappedEntity();
 
@@ -828,7 +828,7 @@ public function testDataMappingIssetSwapped()
         ], $result);
     }
 
-    public function testDataMappingIssetUnsetSwapped()
+    public function testDataMappingIssetUnsetSwapped(): void
     {
         $entity = $this->getSimpleSwappedEntity();
 
@@ -845,7 +845,7 @@ public function testDataMappingIssetUnsetSwapped()
         $this->assertSame('222', $entity->bar);
     }
 
-    public function testToArraySkipAttributesWithUnderscoreInFirstCharacter()
+    public function testToArraySkipAttributesWithUnderscoreInFirstCharacter(): void
     {
         $entity = new class () extends Entity {
             protected $attributes = [
@@ -861,7 +861,7 @@ public function testToArraySkipAttributesWithUnderscoreInFirstCharacter()
         ], $result);
     }
 
-    public function testAsArrayOnlyChanged()
+    public function testAsArrayOnlyChanged(): void
     {
         $entity      = $this->getEntity();
         $entity->bar = 'foo';
@@ -873,7 +873,7 @@ public function testAsArrayOnlyChanged()
         ], $result);
     }
 
-    public function testToRawArray()
+    public function testToRawArray(): void
     {
         $entity = $this->getEntity();
 
@@ -887,7 +887,7 @@ public function testToRawArray()
         ], $result);
     }
 
-    public function testToRawArrayRecursive()
+    public function testToRawArrayRecursive(): void
     {
         $entity         = $this->getEntity();
         $entity->entity = $this->getEntity();
@@ -908,7 +908,7 @@ public function testToRawArrayRecursive()
         ], $result);
     }
 
-    public function testToRawArrayOnlyChanged()
+    public function testToRawArrayOnlyChanged(): void
     {
         $entity      = $this->getEntity();
         $entity->bar = 'foo';
@@ -920,7 +920,7 @@ public function testToRawArrayOnlyChanged()
         ], $result);
     }
 
-    public function testFilledConstruction()
+    public function testFilledConstruction(): void
     {
         $data = [
             'foo' => 'bar',
@@ -932,7 +932,7 @@ public function testFilledConstruction()
         $this->assertSame('baz', $something->bar);
     }
 
-    public function testChangedArray()
+    public function testChangedArray(): void
     {
         $data      = ['bar' => 'baz'];
         $something = new SomeEntity($data);
@@ -948,14 +948,14 @@ public function testChangedArray()
         ], $something->toArray(false));
     }
 
-    public function testHasChangedNotExists()
+    public function testHasChangedNotExists(): void
     {
         $entity = new SomeEntity();
 
         $this->assertFalse($entity->hasChanged('foo'));
     }
 
-    public function testHasChangedNewElement()
+    public function testHasChangedNewElement(): void
     {
         $entity = new SomeEntity();
 
@@ -964,14 +964,14 @@ public function testHasChangedNewElement()
         $this->assertTrue($entity->hasChanged('foo'));
     }
 
-    public function testHasChangedNoChange()
+    public function testHasChangedNoChange(): void
     {
         $entity = $this->getEntity();
 
         $this->assertFalse($entity->hasChanged('default'));
     }
 
-    public function testHasChangedMappedNoChange()
+    public function testHasChangedMappedNoChange(): void
     {
         $entity = $this->getEntity();
 
@@ -980,7 +980,7 @@ public function testHasChangedMappedNoChange()
         $this->assertFalse($entity->hasChanged('createdAt'));
     }
 
-    public function testHasChangedMappedChanged()
+    public function testHasChangedMappedChanged(): void
     {
         $entity = $this->getEntity();
 
@@ -989,7 +989,7 @@ public function testHasChangedMappedChanged()
         $this->assertTrue($entity->hasChanged('createdAt'));
     }
 
-    public function testHasChangedWholeEntity()
+    public function testHasChangedWholeEntity(): void
     {
         $entity = $this->getEntity();
 
@@ -998,14 +998,14 @@ public function testHasChangedWholeEntity()
         $this->assertTrue($entity->hasChanged());
     }
 
-    public function testHasChangedKeyNotExists()
+    public function testHasChangedKeyNotExists(): void
     {
         $entity = $this->getEntity();
 
         $this->assertFalse($entity->hasChanged('xxx'));
     }
 
-    public function testDataMappingIssetSetGetMethod()
+    public function testDataMappingIssetSetGetMethod(): void
     {
         $entity = $this->getEntity();
 
@@ -1020,7 +1020,7 @@ public function testDataMappingIssetSetGetMethod()
         $this->assertTrue($issetReturn);
     }
 
-    public function testJsonSerializableEntity()
+    public function testJsonSerializableEntity(): void
     {
         $entity = $this->getEntity();
         $entity->setBar('foo');
@@ -1084,7 +1084,7 @@ protected function getMappedEntity()
                 'orig' => 'simple',
             ];
 
-            protected function setSimple(string $val)
+            protected function setSimple(string $val): void
             {
                 $this->attributes['simple'] = 'oo:' . $val;
             }
@@ -1184,7 +1184,7 @@ protected function getCastEntity($data = null): Entity
                 'thirteenth' => 'uri',
             ];
 
-            public function setSeventh($seventh)
+            public function setSeventh($seventh): void
             {
                 $this->attributes['seventh'] = $seventh;
             }
diff --git a/tests/system/Events/EventsTest.php b/tests/system/Events/EventsTest.php
index 1a106aca3548..d34afda0c9e4 100644
--- a/tests/system/Events/EventsTest.php
+++ b/tests/system/Events/EventsTest.php
@@ -45,7 +45,7 @@ protected function tearDown(): void
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testInitialize()
+    public function testInitialize(): void
     {
         /**
          * @var Modules $config
@@ -72,10 +72,10 @@ public function testInitialize()
         $this->assertSame(['/peanuts'], Events::getFiles());
     }
 
-    public function testPerformance()
+    public function testPerformance(): void
     {
         $result = null;
-        Events::on('foo', static function ($arg) use (&$result) {
+        Events::on('foo', static function ($arg) use (&$result): void {
             $result = $arg;
         });
         Events::trigger('foo', 'bar');
@@ -85,11 +85,11 @@ public function testPerformance()
         $this->assertGreaterThan(0, count($logged));
     }
 
-    public function testListeners()
+    public function testListeners(): void
     {
-        $callback1 = static function () {
+        $callback1 = static function (): void {
         };
-        $callback2 = static function () {
+        $callback2 = static function (): void {
         };
 
         Events::on('foo', $callback1, EVENT_PRIORITY_HIGH);
@@ -98,11 +98,11 @@ public function testListeners()
         $this->assertSame([$callback1, $callback2], Events::listeners('foo'));
     }
 
-    public function testHandleEvent()
+    public function testHandleEvent(): void
     {
         $result = null;
 
-        Events::on('foo', static function ($arg) use (&$result) {
+        Events::on('foo', static function ($arg) use (&$result): void {
             $result = $arg;
         });
 
@@ -111,7 +111,7 @@ public function testHandleEvent()
         $this->assertSame('bar', $result);
     }
 
-    public function testCancelEvent()
+    public function testCancelEvent(): void
     {
         $result = 0;
 
@@ -122,7 +122,7 @@ public function testCancelEvent()
 
             return false;
         });
-        Events::on('foo', static function ($arg) use (&$result) {
+        Events::on('foo', static function ($arg) use (&$result): void {
             $result = 2;
         });
 
@@ -130,7 +130,7 @@ public function testCancelEvent()
         $this->assertSame(1, $result);
     }
 
-    public function testPriority()
+    public function testPriority(): void
     {
         $result = 0;
 
@@ -151,23 +151,23 @@ public function testPriority()
         $this->assertSame(2, $result);
     }
 
-    public function testPriorityWithMultiple()
+    public function testPriorityWithMultiple(): void
     {
         $result = [];
 
-        Events::on('foo', static function () use (&$result) {
+        Events::on('foo', static function () use (&$result): void {
             $result[] = 'a';
         }, Events::PRIORITY_NORMAL);
 
-        Events::on('foo', static function () use (&$result) {
+        Events::on('foo', static function () use (&$result): void {
             $result[] = 'b';
         }, Events::PRIORITY_LOW);
 
-        Events::on('foo', static function () use (&$result) {
+        Events::on('foo', static function () use (&$result): void {
             $result[] = 'c';
         }, Events::PRIORITY_HIGH);
 
-        Events::on('foo', static function () use (&$result) {
+        Events::on('foo', static function () use (&$result): void {
             $result[] = 'd';
         }, 75);
 
@@ -175,11 +175,11 @@ public function testPriorityWithMultiple()
         $this->assertSame(['c', 'd', 'a', 'b'], $result);
     }
 
-    public function testRemoveListener()
+    public function testRemoveListener(): void
     {
         $result = false;
 
-        $callback = static function () use (&$result) {
+        $callback = static function () use (&$result): void {
             $result = true;
         };
 
@@ -195,11 +195,11 @@ public function testRemoveListener()
         $this->assertFalse($result);
     }
 
-    public function testRemoveListenerTwice()
+    public function testRemoveListenerTwice(): void
     {
         $result = false;
 
-        $callback = static function () use (&$result) {
+        $callback = static function () use (&$result): void {
             $result = true;
         };
 
@@ -216,11 +216,11 @@ public function testRemoveListenerTwice()
         $this->assertFalse($result);
     }
 
-    public function testRemoveUnknownListener()
+    public function testRemoveUnknownListener(): void
     {
         $result = false;
 
-        $callback = static function () use (&$result) {
+        $callback = static function () use (&$result): void {
             $result = true;
         };
 
@@ -236,11 +236,11 @@ public function testRemoveUnknownListener()
         $this->assertTrue($result);
     }
 
-    public function testRemoveAllListenersWithSingleEvent()
+    public function testRemoveAllListenersWithSingleEvent(): void
     {
         $result = false;
 
-        $callback = static function () use (&$result) {
+        $callback = static function () use (&$result): void {
             $result = true;
         };
 
@@ -253,11 +253,11 @@ public function testRemoveAllListenersWithSingleEvent()
         $this->assertSame([], $listeners);
     }
 
-    public function testRemoveAllListenersWithMultipleEvents()
+    public function testRemoveAllListenersWithMultipleEvents(): void
     {
         $result = false;
 
-        $callback = static function () use (&$result) {
+        $callback = static function () use (&$result): void {
             $result = true;
         };
 
@@ -271,19 +271,19 @@ public function testRemoveAllListenersWithMultipleEvents()
     }
 
     // Basically if it doesn't crash this should be good...
-    public function testHandleEventCallableInternalFunc()
+    public function testHandleEventCallableInternalFunc(): void
     {
         Events::on('foo', 'strlen');
 
         $this->assertTrue(Events::trigger('foo', 'bar'));
     }
 
-    public function testHandleEventCallableClass()
+    public function testHandleEventCallableClass(): void
     {
         $box = new class () {
             public $logged;
 
-            public function hold(string $value)
+            public function hold(string $value): void
             {
                 $this->logged = $value;
             }
@@ -296,11 +296,11 @@ public function hold(string $value)
         $this->assertSame('bar', $box->logged);
     }
 
-    public function testSimulate()
+    public function testSimulate(): void
     {
         $result = 0;
 
-        $callback = static function () use (&$result) {
+        $callback = static function () use (&$result): void {
             $result += 2;
         };
 
diff --git a/tests/system/Files/FileCollectionTest.php b/tests/system/Files/FileCollectionTest.php
index cf810ba7be1d..2b230d9b485e 100644
--- a/tests/system/Files/FileCollectionTest.php
+++ b/tests/system/Files/FileCollectionTest.php
@@ -43,14 +43,14 @@ public static function setUpBeforeClass(): void
         helper(['filesystem']);
     }
 
-    public function testResolveDirectoryDirectory()
+    public function testResolveDirectoryDirectory(): void
     {
         $method = $this->getPrivateMethodInvoker(FileCollection::class, 'resolveDirectory');
 
         $this->assertSame($this->directory, $method($this->directory));
     }
 
-    public function testResolveDirectoryFile()
+    public function testResolveDirectoryFile(): void
     {
         $method = $this->getPrivateMethodInvoker(FileCollection::class, 'resolveDirectory');
 
@@ -60,7 +60,7 @@ public function testResolveDirectoryFile()
         $method($this->file);
     }
 
-    public function testResolveDirectorySymlink()
+    public function testResolveDirectorySymlink(): void
     {
         // Create a symlink to test
         $link = sys_get_temp_dir() . DIRECTORY_SEPARATOR . bin2hex(random_bytes(4));
@@ -73,14 +73,14 @@ public function testResolveDirectorySymlink()
         unlink($link);
     }
 
-    public function testResolveFileFile()
+    public function testResolveFileFile(): void
     {
         $method = $this->getPrivateMethodInvoker(FileCollection::class, 'resolveFile');
 
         $this->assertSame($this->file, $method($this->file));
     }
 
-    public function testResolveFileSymlink()
+    public function testResolveFileSymlink(): void
     {
         // Create a symlink to test
         $link = sys_get_temp_dir() . DIRECTORY_SEPARATOR . bin2hex(random_bytes(4));
@@ -93,7 +93,7 @@ public function testResolveFileSymlink()
         unlink($link);
     }
 
-    public function testResolveFileDirectory()
+    public function testResolveFileDirectory(): void
     {
         $method = $this->getPrivateMethodInvoker(FileCollection::class, 'resolveFile');
 
@@ -103,7 +103,7 @@ public function testResolveFileDirectory()
         $method($this->directory);
     }
 
-    public function testConstructorAddsFiles()
+    public function testConstructorAddsFiles(): void
     {
         $expected = [
             $this->directory . 'apple.php',
@@ -119,7 +119,7 @@ public function testConstructorAddsFiles()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testConstructorCallsDefine()
+    public function testConstructorCallsDefine(): void
     {
         $collection = new class () extends FileCollection {
             protected function define(): void
@@ -131,7 +131,7 @@ protected function define(): void
         $this->assertSame([$this->file], $collection->get());
     }
 
-    public function testAddStringFile()
+    public function testAddStringFile(): void
     {
         $files = new FileCollection();
 
@@ -140,7 +140,7 @@ public function testAddStringFile()
         $this->assertSame([$this->file], $files->get());
     }
 
-    public function testAddStringFileRecursiveDoesNothing()
+    public function testAddStringFileRecursiveDoesNothing(): void
     {
         $files = new FileCollection();
 
@@ -149,7 +149,7 @@ public function testAddStringFileRecursiveDoesNothing()
         $this->assertSame([$this->file], $files->get());
     }
 
-    public function testAddStringDirectory()
+    public function testAddStringDirectory(): void
     {
         $files = new FileCollection();
 
@@ -164,7 +164,7 @@ public function testAddStringDirectory()
         $this->assertSame($expected, $files->get());
     }
 
-    public function testAddStringDirectoryRecursive()
+    public function testAddStringDirectoryRecursive(): void
     {
         $files = new FileCollection();
 
@@ -180,7 +180,7 @@ public function testAddStringDirectoryRecursive()
         $this->assertSame($expected, $files->get());
     }
 
-    public function testAddArrayFiles()
+    public function testAddArrayFiles(): void
     {
         $files = new FileCollection();
 
@@ -197,7 +197,7 @@ public function testAddArrayFiles()
         $this->assertSame($expected, $files->get());
     }
 
-    public function testAddArrayDirectoryAndFile()
+    public function testAddArrayDirectoryAndFile(): void
     {
         $files = new FileCollection();
 
@@ -216,7 +216,7 @@ public function testAddArrayDirectoryAndFile()
         $this->assertSame($expected, $files->get());
     }
 
-    public function testAddArrayRecursive()
+    public function testAddArrayRecursive(): void
     {
         $files = new FileCollection();
 
@@ -236,7 +236,7 @@ public function testAddArrayRecursive()
         $this->assertSame($expected, $files->get());
     }
 
-    public function testAddFile()
+    public function testAddFile(): void
     {
         $collection = new FileCollection();
         $this->assertSame([], $this->getPrivateProperty($collection, 'files'));
@@ -245,7 +245,7 @@ public function testAddFile()
         $this->assertSame([$this->file], $this->getPrivateProperty($collection, 'files'));
     }
 
-    public function testAddFileMissing()
+    public function testAddFileMissing(): void
     {
         $collection = new FileCollection();
 
@@ -255,7 +255,7 @@ public function testAddFileMissing()
         $collection->addFile('TheHillsAreAlive.bmp');
     }
 
-    public function testAddFileDirectory()
+    public function testAddFileDirectory(): void
     {
         $collection = new FileCollection();
 
@@ -265,7 +265,7 @@ public function testAddFileDirectory()
         $collection->addFile($this->directory);
     }
 
-    public function testAddFiles()
+    public function testAddFiles(): void
     {
         $collection = new FileCollection();
         $files      = [
@@ -277,7 +277,7 @@ public function testAddFiles()
         $this->assertSame($files, $this->getPrivateProperty($collection, 'files'));
     }
 
-    public function testGet()
+    public function testGet(): void
     {
         $collection = new FileCollection();
         $collection->addFile($this->file);
@@ -285,7 +285,7 @@ public function testGet()
         $this->assertSame([$this->file], $collection->get());
     }
 
-    public function testGetSorts()
+    public function testGetSorts(): void
     {
         $collection = new FileCollection();
         $files      = [
@@ -298,7 +298,7 @@ public function testGetSorts()
         $this->assertSame(array_reverse($files), $collection->get());
     }
 
-    public function testGetUniques()
+    public function testGetUniques(): void
     {
         $collection = new FileCollection();
         $files      = [
@@ -310,7 +310,7 @@ public function testGetUniques()
         $this->assertSame([$this->file], $collection->get());
     }
 
-    public function testSet()
+    public function testSet(): void
     {
         $collection = new FileCollection();
 
@@ -318,7 +318,7 @@ public function testSet()
         $this->assertSame([$this->file], $collection->get());
     }
 
-    public function testSetInvalid()
+    public function testSetInvalid(): void
     {
         $collection = new FileCollection();
 
@@ -328,7 +328,7 @@ public function testSetInvalid()
         $collection->set(['flerb']);
     }
 
-    public function testRemoveFile()
+    public function testRemoveFile(): void
     {
         $collection = new FileCollection();
         $files      = [
@@ -343,7 +343,7 @@ public function testRemoveFile()
         $this->assertSame([$this->directory . 'apple.php'], $collection->get());
     }
 
-    public function testRemoveFiles()
+    public function testRemoveFiles(): void
     {
         $collection = new FileCollection();
         $files      = [
@@ -358,7 +358,7 @@ public function testRemoveFiles()
         $this->assertSame([], $collection->get());
     }
 
-    public function testAddDirectoryInvalid()
+    public function testAddDirectoryInvalid(): void
     {
         $collection = new FileCollection();
 
@@ -368,7 +368,7 @@ public function testAddDirectoryInvalid()
         $collection->addDirectory($this->file);
     }
 
-    public function testAddDirectory()
+    public function testAddDirectory(): void
     {
         $collection = new FileCollection();
         $expected   = [
@@ -382,7 +382,7 @@ public function testAddDirectory()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testAddDirectoryRecursive()
+    public function testAddDirectoryRecursive(): void
     {
         $collection = new FileCollection();
         $expected   = [
@@ -397,7 +397,7 @@ public function testAddDirectoryRecursive()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testAddDirectories()
+    public function testAddDirectories(): void
     {
         $collection = new FileCollection();
         $expected   = [
@@ -415,7 +415,7 @@ public function testAddDirectories()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testAddDirectoriesRecursive()
+    public function testAddDirectoriesRecursive(): void
     {
         $collection = new FileCollection();
         $expected   = [
@@ -434,7 +434,7 @@ public function testAddDirectoriesRecursive()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testRemovePatternEmpty()
+    public function testRemovePatternEmpty(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -446,7 +446,7 @@ public function testRemovePatternEmpty()
         $this->assertSame($files, $collection->get());
     }
 
-    public function testRemovePatternRegex()
+    public function testRemovePatternRegex(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -461,7 +461,7 @@ public function testRemovePatternRegex()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testRemovePatternPseudo()
+    public function testRemovePatternPseudo(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -476,7 +476,7 @@ public function testRemovePatternPseudo()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testRemovePatternScope()
+    public function testRemovePatternScope(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -490,7 +490,7 @@ public function testRemovePatternScope()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testRetainPatternEmpty()
+    public function testRetainPatternEmpty(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -502,7 +502,7 @@ public function testRetainPatternEmpty()
         $this->assertSame($files, $collection->get());
     }
 
-    public function testRetainPatternRegex()
+    public function testRetainPatternRegex(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -517,7 +517,7 @@ public function testRetainPatternRegex()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testRetainPatternPseudo()
+    public function testRetainPatternPseudo(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -531,7 +531,7 @@ public function testRetainPatternPseudo()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testRetainPatternScope()
+    public function testRetainPatternScope(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -546,7 +546,7 @@ public function testRetainPatternScope()
         $this->assertSame($expected, $collection->get());
     }
 
-    public function testCount()
+    public function testCount(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
@@ -554,7 +554,7 @@ public function testCount()
         $this->assertCount(4, $collection);
     }
 
-    public function testIterable()
+    public function testIterable(): void
     {
         $collection = new FileCollection();
         $collection->addDirectory(SUPPORTPATH . 'Files', true);
diff --git a/tests/system/Files/FileTest.php b/tests/system/Files/FileTest.php
index 0019e7decbb3..32a870de0bb4 100644
--- a/tests/system/Files/FileTest.php
+++ b/tests/system/Files/FileTest.php
@@ -22,28 +22,28 @@
  */
 final class FileTest extends CIUnitTestCase
 {
-    public function testNewGoodChecked()
+    public function testNewGoodChecked(): void
     {
         $path = SYSTEMPATH . 'Common.php';
         $file = new File($path, true);
         $this->assertSame($path, $file->getRealPath());
     }
 
-    public function testNewGoodUnchecked()
+    public function testNewGoodUnchecked(): void
     {
         $path = SYSTEMPATH . 'Common.php';
         $file = new File($path, false);
         $this->assertSame($path, $file->getRealPath());
     }
 
-    public function testNewBadUnchecked()
+    public function testNewBadUnchecked(): void
     {
         $path = SYSTEMPATH . 'bogus';
         $file = new File($path, false);
         $this->assertFalse($file->getRealPath());
     }
 
-    public function testGuessExtension()
+    public function testGuessExtension(): void
     {
         $file = new File(SYSTEMPATH . 'Common.php');
         $this->assertSame('php', $file->guessExtension());
@@ -77,41 +77,41 @@ public function testGuessExtensionOnZip(): void
         unlink($tmp);
     }
 
-    public function testRandomName()
+    public function testRandomName(): void
     {
         $file    = new File(SYSTEMPATH . 'Common.php');
         $result1 = $file->getRandomName();
         $this->assertNotSame($result1, $file->getRandomName());
     }
 
-    public function testCanAccessSplFileInfoMethods()
+    public function testCanAccessSplFileInfoMethods(): void
     {
         $file = new File(SYSTEMPATH . 'Common.php');
         $this->assertSame('file', $file->getType());
     }
 
-    public function testGetSizeReturnsKB()
+    public function testGetSizeReturnsKB(): void
     {
         $file = new File(SYSTEMPATH . 'Common.php');
         $size = number_format(filesize(SYSTEMPATH . 'Common.php') / 1024, 3);
         $this->assertSame($size, $file->getSizeByUnit('kb'));
     }
 
-    public function testGetSizeReturnsMB()
+    public function testGetSizeReturnsMB(): void
     {
         $file = new File(SYSTEMPATH . 'Common.php');
         $size = number_format(filesize(SYSTEMPATH . 'Common.php') / 1024 / 1024, 3);
         $this->assertSame($size, $file->getSizeByUnit('mb'));
     }
 
-    public function testGetSizeReturnsBytes()
+    public function testGetSizeReturnsBytes(): void
     {
         $file = new File(SYSTEMPATH . 'Common.php');
         $size = filesize(SYSTEMPATH . 'Common.php');
         $this->assertSame($size, $file->getSizeByUnit('b'));
     }
 
-    public function testThrowsExceptionIfNotAFile()
+    public function testThrowsExceptionIfNotAFile(): void
     {
         $this->expectException(FileNotFoundException::class);
 
diff --git a/tests/system/Files/FileWithVfsTest.php b/tests/system/Files/FileWithVfsTest.php
index 6e5af6b3974c..e7c68378e34b 100644
--- a/tests/system/Files/FileWithVfsTest.php
+++ b/tests/system/Files/FileWithVfsTest.php
@@ -46,55 +46,55 @@ protected function tearDown(): void
         $this->root = null;
     }
 
-    public function testDestinationUnknown()
+    public function testDestinationUnknown(): void
     {
         $destination = $this->start . 'charlie/cherry.php';
         $this->assertSame($destination, $this->file->getDestination($destination));
     }
 
-    public function testDestinationSameFileSameFolder()
+    public function testDestinationSameFileSameFolder(): void
     {
         $destination = $this->start . 'able/apple.php';
         $this->assertSame($this->start . 'able/apple_1.php', $this->file->getDestination($destination));
     }
 
-    public function testDestinationSameFileDifferentFolder()
+    public function testDestinationSameFileDifferentFolder(): void
     {
         $destination = $this->start . 'baker/apple.php';
         $this->assertSame($destination, $this->file->getDestination($destination));
     }
 
-    public function testDestinationDifferentFileSameFolder()
+    public function testDestinationDifferentFileSameFolder(): void
     {
         $destination = $this->start . 'able/date.php';
         $this->assertSame($destination, $this->file->getDestination($destination));
     }
 
-    public function testDestinationDifferentFileDifferentFolder()
+    public function testDestinationDifferentFileDifferentFolder(): void
     {
         $destination = $this->start . 'baker/date.php';
         $this->assertSame($destination, $this->file->getDestination($destination));
     }
 
-    public function testDestinationExistingFileDifferentFolder()
+    public function testDestinationExistingFileDifferentFolder(): void
     {
         $destination = $this->start . 'baker/banana.php';
         $this->assertSame($this->start . 'baker/banana_1.php', $this->file->getDestination($destination));
     }
 
-    public function testDestinationDelimited()
+    public function testDestinationDelimited(): void
     {
         $destination = $this->start . 'able/fig_3.php';
         $this->assertSame($this->start . 'able/fig_4.php', $this->file->getDestination($destination));
     }
 
-    public function testDestinationDelimitedAlpha()
+    public function testDestinationDelimitedAlpha(): void
     {
         $destination = $this->start . 'able/prune_ripe.php';
         $this->assertSame($this->start . 'able/prune_ripe_1.php', $this->file->getDestination($destination));
     }
 
-    public function testMoveNormal()
+    public function testMoveNormal(): void
     {
         $destination = $this->start . 'baker';
         $this->file->move($destination);
@@ -102,7 +102,7 @@ public function testMoveNormal()
         $this->assertFalse($this->root->hasChild('able/apple.php'));
     }
 
-    public function testMoveRename()
+    public function testMoveRename(): void
     {
         $destination = $this->start . 'baker';
         $this->file->move($destination, 'popcorn.php');
@@ -110,7 +110,7 @@ public function testMoveRename()
         $this->assertFalse($this->root->hasChild('able/apple.php'));
     }
 
-    public function testMoveOverwrite()
+    public function testMoveOverwrite(): void
     {
         $destination = $this->start . 'baker';
         $this->file->move($destination, 'banana.php', true);
@@ -118,7 +118,7 @@ public function testMoveOverwrite()
         $this->assertFalse($this->root->hasChild('able/apple.php'));
     }
 
-    public function testMoveDontOverwrite()
+    public function testMoveDontOverwrite(): void
     {
         $destination = $this->start . 'baker';
         $this->file->move($destination, 'banana.php');
@@ -126,7 +126,7 @@ public function testMoveDontOverwrite()
         $this->assertFalse($this->root->hasChild('able/apple.php'));
     }
 
-    public function testMoveFailure()
+    public function testMoveFailure(): void
     {
         $this->expectException('Exception');
 
@@ -140,7 +140,7 @@ public function testMoveFailure()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1782
      */
-    public function testMoveReturnsNewInstance()
+    public function testMoveReturnsNewInstance(): void
     {
         $destination = $this->start . 'baker';
         $file        = $this->file->move($destination);
diff --git a/tests/system/Filters/CSRFTest.php b/tests/system/Filters/CSRFTest.php
index 9d690095af8d..1f588c5874f3 100644
--- a/tests/system/Filters/CSRFTest.php
+++ b/tests/system/Filters/CSRFTest.php
@@ -41,7 +41,7 @@ protected function setUp(): void
         $this->config = new \Config\Filters();
     }
 
-    public function testDoNotCheckCliRequest()
+    public function testDoNotCheckCliRequest(): void
     {
         $this->config->globals = [
             'before' => ['csrf'],
@@ -59,7 +59,7 @@ public function testDoNotCheckCliRequest()
         $this->assertSame($this->request, $request);
     }
 
-    public function testPassGetRequest()
+    public function testPassGetRequest(): void
     {
         $this->config->globals = [
             'before' => ['csrf'],
diff --git a/tests/system/Filters/DebugToolbarTest.php b/tests/system/Filters/DebugToolbarTest.php
index 8b98b870f008..f66e63bf22e9 100644
--- a/tests/system/Filters/DebugToolbarTest.php
+++ b/tests/system/Filters/DebugToolbarTest.php
@@ -42,7 +42,7 @@ protected function setUp(): void
         $this->response = Services::response();
     }
 
-    public function testDebugToolbarFilter()
+    public function testDebugToolbarFilter(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
diff --git a/tests/system/Filters/FiltersTest.php b/tests/system/Filters/FiltersTest.php
index 80bd9cbbf0ca..a89950c71750 100644
--- a/tests/system/Filters/FiltersTest.php
+++ b/tests/system/Filters/FiltersTest.php
@@ -76,7 +76,7 @@ private function createFilters(FiltersConfig $config, $request = null): Filters
         return new Filters($config, $request, $this->response);
     }
 
-    public function testProcessMethodDetectsCLI()
+    public function testProcessMethodDetectsCLI(): void
     {
         $_SERVER['argv'] = [
             'spark',
@@ -104,7 +104,7 @@ public function testProcessMethodDetectsCLI()
         $this->assertSame($expected, $filters->initialize()->getFilters());
     }
 
-    public function testProcessMethodDetectsGetRequests()
+    public function testProcessMethodDetectsGetRequests(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -125,7 +125,7 @@ public function testProcessMethodDetectsGetRequests()
         $this->assertSame($expected, $filters->initialize()->getFilters());
     }
 
-    public function testProcessMethodRespectsMethod()
+    public function testProcessMethodRespectsMethod(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -150,7 +150,7 @@ public function testProcessMethodRespectsMethod()
         $this->assertSame($expected, $filters->initialize()->getFilters());
     }
 
-    public function testProcessMethodIgnoresMethod()
+    public function testProcessMethodIgnoresMethod(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'DELETE';
 
@@ -175,7 +175,7 @@ public function testProcessMethodIgnoresMethod()
         $this->assertSame($expected, $filters->initialize()->getFilters());
     }
 
-    public function testProcessMethodProcessGlobals()
+    public function testProcessMethodProcessGlobals(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -223,7 +223,7 @@ public function provideExcept(): iterable
     /**
      * @dataProvider provideExcept
      */
-    public function testProcessMethodProcessGlobalsWithExcept(array $except)
+    public function testProcessMethodProcessGlobalsWithExcept(array $except): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -256,7 +256,7 @@ public function testProcessMethodProcessGlobalsWithExcept(array $except)
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testProcessMethodProcessesFiltersBefore()
+    public function testProcessMethodProcessesFiltersBefore(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -285,7 +285,7 @@ public function testProcessMethodProcessesFiltersBefore()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testProcessMethodProcessesFiltersAfter()
+    public function testProcessMethodProcessesFiltersAfter(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -316,7 +316,7 @@ public function testProcessMethodProcessesFiltersAfter()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testProcessMethodProcessesCombined()
+    public function testProcessMethodProcessesCombined(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -364,7 +364,7 @@ public function testProcessMethodProcessesCombined()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testProcessMethodProcessesCombinedAfterForToolbar()
+    public function testProcessMethodProcessesCombinedAfterForToolbar(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -405,7 +405,7 @@ public function testProcessMethodProcessesCombinedAfterForToolbar()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testRunThrowsWithInvalidAlias()
+    public function testRunThrowsWithInvalidAlias(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -425,7 +425,7 @@ public function testRunThrowsWithInvalidAlias()
         $filters->run($uri);
     }
 
-    public function testCustomFiltersLoad()
+    public function testCustomFiltersLoad(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -450,7 +450,7 @@ public function testCustomFiltersLoad()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4720
      */
-    public function testAllCustomFiltersAreDiscoveredInConstructor()
+    public function testAllCustomFiltersAreDiscoveredInConstructor(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -465,7 +465,7 @@ public function testAllCustomFiltersAreDiscoveredInConstructor()
         $this->assertContains('test-customfilter', array_keys($configFilters->aliases));
     }
 
-    public function testRunThrowsWithInvalidClassType()
+    public function testRunThrowsWithInvalidClassType(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -485,7 +485,7 @@ public function testRunThrowsWithInvalidClassType()
         $filters->run($uri);
     }
 
-    public function testRunDoesBefore()
+    public function testRunDoesBefore(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -505,7 +505,7 @@ public function testRunDoesBefore()
         $this->assertSame('http://google.com', $request->getBody());
     }
 
-    public function testRunDoesAfter()
+    public function testRunDoesAfter(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -525,7 +525,7 @@ public function testRunDoesAfter()
         $this->assertSame('http://google.com', $response->getBody());
     }
 
-    public function testShortCircuit()
+    public function testShortCircuit(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -546,7 +546,7 @@ public function testShortCircuit()
         $this->assertSame('http://google.com', $response->getBody());
     }
 
-    public function testOtherResult()
+    public function testOtherResult(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -572,7 +572,7 @@ public function testOtherResult()
         $this->assertSame('This is curious', $response);
     }
 
-    public function testBeforeExceptString()
+    public function testBeforeExceptString(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -605,7 +605,7 @@ public function testBeforeExceptString()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testBeforeExceptInapplicable()
+    public function testBeforeExceptInapplicable(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -639,7 +639,7 @@ public function testBeforeExceptInapplicable()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testAfterExceptString()
+    public function testAfterExceptString(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -672,7 +672,7 @@ public function testAfterExceptString()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testAfterExceptInapplicable()
+    public function testAfterExceptInapplicable(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -708,7 +708,7 @@ public function testAfterExceptInapplicable()
         $this->assertSame($expected, $filters->initialize($uri)->getFilters());
     }
 
-    public function testAddFilter()
+    public function testAddFilter(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -729,7 +729,7 @@ public function testAddFilter()
         $this->assertContains('some_alias', $filters['before']);
     }
 
-    public function testAddFilterSection()
+    public function testAddFilterSection(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -745,7 +745,7 @@ public function testAddFilterSection()
         $this->assertContains('another', $list['before']);
     }
 
-    public function testInitializeTwice()
+    public function testInitializeTwice(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -762,7 +762,7 @@ public function testInitializeTwice()
         $this->assertContains('another', $list['before']);
     }
 
-    public function testEnableFilter()
+    public function testEnableFilter(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -783,7 +783,7 @@ public function testEnableFilter()
         $this->assertContains('google', $filters['before']);
     }
 
-    public function testEnableFilterWithArguments()
+    public function testEnableFilterWithArguments(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -815,7 +815,7 @@ public function testEnableFilterWithArguments()
         $this->assertSame('admin;super', $response->getBody());
     }
 
-    public function testEnableFilterWithNoArguments()
+    public function testEnableFilterWithNoArguments(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -845,7 +845,7 @@ public function testEnableFilterWithNoArguments()
         $this->assertSame('Is null', $response->getBody());
     }
 
-    public function testEnableNonFilter()
+    public function testEnableNonFilter(): void
     {
         $this->expectException(FilterException::class);
 
@@ -868,7 +868,7 @@ public function testEnableNonFilter()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1664
      */
-    public function testMatchesURICaseInsensitively()
+    public function testMatchesURICaseInsensitively(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -916,7 +916,7 @@ public function testMatchesURICaseInsensitively()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1907
      */
-    public function testFilterMatching()
+    public function testFilterMatching(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -952,7 +952,7 @@ public function testFilterMatching()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1907
      */
-    public function testGlobalFilterMatching()
+    public function testGlobalFilterMatching(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -994,7 +994,7 @@ public function testGlobalFilterMatching()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1907
      */
-    public function testCombinedFilterMatching()
+    public function testCombinedFilterMatching(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -1042,7 +1042,7 @@ public function testCombinedFilterMatching()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1907
      */
-    public function testSegmentedFilterMatching()
+    public function testSegmentedFilterMatching(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
@@ -1085,7 +1085,7 @@ public function testSegmentedFilterMatching()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2831
      */
-    public function testFilterAliasMultiple()
+    public function testFilterAliasMultiple(): void
     {
         $config = [
             'aliases' => [
@@ -1110,7 +1110,7 @@ public function testFilterAliasMultiple()
         $this->assertSame('http://exampleMultipleCSP.com', $request->header('x-csp')->getValue());
     }
 
-    public function testFilterClass()
+    public function testFilterClass(): void
     {
         $config = [
             'aliases' => [
@@ -1140,7 +1140,7 @@ public function testFilterClass()
         $this->assertSame($expected, $filters->getFiltersClass());
     }
 
-    public function testReset()
+    public function testReset(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'GET';
 
diff --git a/tests/system/Filters/HoneypotTest.php b/tests/system/Filters/HoneypotTest.php
index efde6d372dff..8bd9405e65cf 100644
--- a/tests/system/Filters/HoneypotTest.php
+++ b/tests/system/Filters/HoneypotTest.php
@@ -49,7 +49,7 @@ protected function setUp(): void
         $_POST[$this->honey->name] = 'hey';
     }
 
-    public function testBeforeTriggered()
+    public function testBeforeTriggered(): void
     {
         $this->config->globals = [
             'before' => ['honeypot'],
@@ -66,7 +66,7 @@ public function testBeforeTriggered()
         $filters->run($uri, 'before');
     }
 
-    public function testBeforeClean()
+    public function testBeforeClean(): void
     {
         $this->config->globals = [
             'before' => ['honeypot'],
@@ -90,7 +90,7 @@ public function testBeforeClean()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testAfter()
+    public function testAfter(): void
     {
         $this->config->globals = [
             'before' => [],
@@ -112,7 +112,7 @@ public function testAfter()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testAfterNotApplicable()
+    public function testAfterNotApplicable(): void
     {
         $this->config->globals = [
             'before' => [],
diff --git a/tests/system/Filters/InvalidCharsTest.php b/tests/system/Filters/InvalidCharsTest.php
index 705d3bb70f0e..7a56746d7bcb 100644
--- a/tests/system/Filters/InvalidCharsTest.php
+++ b/tests/system/Filters/InvalidCharsTest.php
@@ -67,7 +67,7 @@ private function createRequest(): IncomingRequest
     /**
      * @doesNotPerformAssertions
      */
-    public function testBeforeDoNothingWhenCLIRequest()
+    public function testBeforeDoNothingWhenCLIRequest(): void
     {
         $cliRequest = new CLIRequest(new MockAppConfig());
 
@@ -77,7 +77,7 @@ public function testBeforeDoNothingWhenCLIRequest()
     /**
      * @doesNotPerformAssertions
      */
-    public function testBeforeValidString()
+    public function testBeforeValidString(): void
     {
         $_POST['val'] = [
             'valid string',
@@ -87,7 +87,7 @@ public function testBeforeValidString()
         $this->invalidChars->before($this->request);
     }
 
-    public function testBeforeInvalidUTF8StringCausesException()
+    public function testBeforeInvalidUTF8StringCausesException(): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('Invalid UTF-8 characters in post:');
@@ -101,7 +101,7 @@ public function testBeforeInvalidUTF8StringCausesException()
         $this->invalidChars->before($this->request);
     }
 
-    public function testBeforeInvalidControlCharCausesException()
+    public function testBeforeInvalidControlCharCausesException(): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('Invalid Control characters in cookie:');
@@ -117,7 +117,7 @@ public function testBeforeInvalidControlCharCausesException()
      *
      * @dataProvider stringWithLineBreakAndTabProvider
      */
-    public function testCheckControlStringWithLineBreakAndTabReturnsTheString(string $input)
+    public function testCheckControlStringWithLineBreakAndTabReturnsTheString(string $input): void
     {
         $_GET['val'] = $input;
 
@@ -138,7 +138,7 @@ public function stringWithLineBreakAndTabProvider(): iterable
     /**
      * @dataProvider stringWithControlCharsProvider
      */
-    public function testCheckControlStringWithControlCharsCausesException(string $input)
+    public function testCheckControlStringWithControlCharsCausesException(string $input): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('Invalid Control characters in get:');
diff --git a/tests/system/Filters/SecureHeadersTest.php b/tests/system/Filters/SecureHeadersTest.php
index c1014d491622..5e9d5f1660c1 100644
--- a/tests/system/Filters/SecureHeadersTest.php
+++ b/tests/system/Filters/SecureHeadersTest.php
@@ -21,7 +21,7 @@
  */
 final class SecureHeadersTest extends CIUnitTestCase
 {
-    public function testAfter()
+    public function testAfter(): void
     {
         $filter   = new SecureHeaders();
         $request  = Services::request(null, false);
diff --git a/tests/system/Filters/fixtures/GoogleCurious.php b/tests/system/Filters/fixtures/GoogleCurious.php
index 53d8c7f2b337..574e6a63b6a6 100644
--- a/tests/system/Filters/fixtures/GoogleCurious.php
+++ b/tests/system/Filters/fixtures/GoogleCurious.php
@@ -22,7 +22,7 @@ public function before(RequestInterface $request, $arguments = null)
         return 'This is curious';
     }
 
-    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null): void
     {
     }
 }
diff --git a/tests/system/Filters/fixtures/GoogleEmpty.php b/tests/system/Filters/fixtures/GoogleEmpty.php
index 16d4eb19347a..9653f79d8118 100644
--- a/tests/system/Filters/fixtures/GoogleEmpty.php
+++ b/tests/system/Filters/fixtures/GoogleEmpty.php
@@ -22,7 +22,7 @@ public function before(RequestInterface $request, $arguments = null)
         return '';
     }
 
-    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null): void
     {
     }
 }
diff --git a/tests/system/Filters/fixtures/GoogleYou.php b/tests/system/Filters/fixtures/GoogleYou.php
index 456d10afab0e..e8a32a69342b 100644
--- a/tests/system/Filters/fixtures/GoogleYou.php
+++ b/tests/system/Filters/fixtures/GoogleYou.php
@@ -26,7 +26,7 @@ public function before(RequestInterface $request, $arguments = null)
         return $response;
     }
 
-    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null): void
     {
     }
 }
diff --git a/tests/system/Filters/fixtures/Multiple1.php b/tests/system/Filters/fixtures/Multiple1.php
index 0a660db44141..162e1b416022 100644
--- a/tests/system/Filters/fixtures/Multiple1.php
+++ b/tests/system/Filters/fixtures/Multiple1.php
@@ -24,7 +24,7 @@ public function before(RequestInterface $request, $arguments = null)
         return $request;
     }
 
-    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null): void
     {
     }
 }
diff --git a/tests/system/Filters/fixtures/Multiple2.php b/tests/system/Filters/fixtures/Multiple2.php
index 12603dbc473a..342a10e849ed 100644
--- a/tests/system/Filters/fixtures/Multiple2.php
+++ b/tests/system/Filters/fixtures/Multiple2.php
@@ -24,7 +24,7 @@ public function before(RequestInterface $request, $arguments = null)
         return $request;
     }
 
-    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null): void
     {
     }
 }
diff --git a/tests/system/Format/FormatTest.php b/tests/system/Format/FormatTest.php
index 3ffd23c900af..7cb7d888ed9c 100644
--- a/tests/system/Format/FormatTest.php
+++ b/tests/system/Format/FormatTest.php
@@ -29,7 +29,7 @@ protected function setUp(): void
         $this->format = new Format(new \Config\Format());
     }
 
-    public function testFormatConfigType()
+    public function testFormatConfigType(): void
     {
         $config = new \Config\Format();
         $format = new Format($config);
@@ -38,19 +38,19 @@ public function testFormatConfigType()
         $this->assertSame($config, $format->getConfig());
     }
 
-    public function testGetFormatter()
+    public function testGetFormatter(): void
     {
         $this->assertInstanceof(FormatterInterface::class, $this->format->getFormatter('application/json'));
     }
 
-    public function testGetFormatterExpectsExceptionOnUndefinedMime()
+    public function testGetFormatterExpectsExceptionOnUndefinedMime(): void
     {
         $this->expectException(FormatException::class);
         $this->expectExceptionMessage('No Formatter defined for mime type: "application/x-httpd-php".');
         $this->format->getFormatter('application/x-httpd-php');
     }
 
-    public function testGetFormatterExpectsExceptionOnUndefinedClass()
+    public function testGetFormatterExpectsExceptionOnUndefinedClass(): void
     {
         $this->format->getConfig()->formatters = array_merge(
             $this->format->getConfig()->formatters,
@@ -62,7 +62,7 @@ public function testGetFormatterExpectsExceptionOnUndefinedClass()
         $this->format->getFormatter('text/xml');
     }
 
-    public function testGetFormatterExpectsExceptionOnClassNotImplementingFormatterInterface()
+    public function testGetFormatterExpectsExceptionOnClassNotImplementingFormatterInterface(): void
     {
         $this->format->getConfig()->formatters = array_merge(
             $this->format->getConfig()->formatters,
diff --git a/tests/system/Format/JSONFormatterTest.php b/tests/system/Format/JSONFormatterTest.php
index 5ca818965033..b433f1ddec9b 100644
--- a/tests/system/Format/JSONFormatterTest.php
+++ b/tests/system/Format/JSONFormatterTest.php
@@ -29,7 +29,7 @@ protected function setUp(): void
         $this->jsonFormatter = new JSONFormatter();
     }
 
-    public function testBasicJSON()
+    public function testBasicJSON(): void
     {
         $data = [
             'foo' => 'bar',
@@ -42,7 +42,7 @@ public function testBasicJSON()
         $this->assertSame($expected, $this->jsonFormatter->format($data));
     }
 
-    public function testUnicodeOutput()
+    public function testUnicodeOutput(): void
     {
         $data = [
             'foo' => 'База данни грешка',
@@ -55,7 +55,7 @@ public function testUnicodeOutput()
         $this->assertSame($expected, $this->jsonFormatter->format($data));
     }
 
-    public function testKeepsURLs()
+    public function testKeepsURLs(): void
     {
         $data = [
             'foo' => 'https://www.example.com/foo/bar',
@@ -68,7 +68,7 @@ public function testKeepsURLs()
         $this->assertSame($expected, $this->jsonFormatter->format($data));
     }
 
-    public function testJSONError()
+    public function testJSONError(): void
     {
         $this->expectException(RuntimeException::class);
 
diff --git a/tests/system/Format/XMLFormatterTest.php b/tests/system/Format/XMLFormatterTest.php
index a97b108b088d..b6606c1a3d19 100644
--- a/tests/system/Format/XMLFormatterTest.php
+++ b/tests/system/Format/XMLFormatterTest.php
@@ -29,7 +29,7 @@ protected function setUp(): void
         $this->xmlFormatter = new XMLFormatter();
     }
 
-    public function testBasicXML()
+    public function testBasicXML(): void
     {
         $data = [
             'foo' => 'bar',
@@ -44,7 +44,7 @@ public function testBasicXML()
         $this->assertSame($expected, $this->xmlFormatter->format($data));
     }
 
-    public function testFormatXMLWithMultilevelArray()
+    public function testFormatXMLWithMultilevelArray(): void
     {
         $data = [
             'foo' => ['bar'],
@@ -59,7 +59,7 @@ public function testFormatXMLWithMultilevelArray()
         $this->assertSame($expected, $this->xmlFormatter->format($data));
     }
 
-    public function testFormatXMLWithMultilevelArrayAndNumericKey()
+    public function testFormatXMLWithMultilevelArrayAndNumericKey(): void
     {
         $data = [
             ['foo'],
@@ -74,7 +74,7 @@ public function testFormatXMLWithMultilevelArrayAndNumericKey()
         $this->assertSame($expected, $this->xmlFormatter->format($data));
     }
 
-    public function testStringFormatting()
+    public function testStringFormatting(): void
     {
         $data     = ['Something'];
         $expected = <<<'EOH'
@@ -86,7 +86,7 @@ public function testStringFormatting()
         $this->assertSame($expected, $this->xmlFormatter->format($data));
     }
 
-    public function testValidatingXmlTags()
+    public function testValidatingXmlTags(): void
     {
         $data = [
             'BBB096630BD' => 'foo',
@@ -104,7 +104,7 @@ public function testValidatingXmlTags()
     /**
      * @dataProvider invalidTagsProvider
      */
-    public function testValidatingInvalidTags(string $expected, array $input)
+    public function testValidatingInvalidTags(string $expected, array $input): void
     {
         $expectedXML = <<<EOH
             <?xml version="1.0"?>
@@ -145,7 +145,7 @@ public function invalidTagsProvider(): iterable
         ];
     }
 
-    public function testDeepNestedArrayToXml()
+    public function testDeepNestedArrayToXml(): void
     {
         $data = [
             'data' => [
diff --git a/tests/system/HTTP/CLIRequestTest.php b/tests/system/HTTP/CLIRequestTest.php
index 69106adf2219..40bf2aad3a53 100644
--- a/tests/system/HTTP/CLIRequestTest.php
+++ b/tests/system/HTTP/CLIRequestTest.php
@@ -38,7 +38,7 @@ protected function setUp(): void
         $_GET  = [];
     }
 
-    public function testParsingSegments()
+    public function testParsingSegments(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -60,7 +60,7 @@ public function testParsingSegments()
         $this->assertSame($segments, $this->request->getSegments());
     }
 
-    public function testParsingSegmentsWithHTMLMetaChars()
+    public function testParsingSegmentsWithHTMLMetaChars(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -84,7 +84,7 @@ public function testParsingSegmentsWithHTMLMetaChars()
         $this->assertSame($segments, $this->request->getSegments());
     }
 
-    public function testParsingOptions()
+    public function testParsingOptions(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -107,7 +107,7 @@ public function testParsingOptions()
         $this->assertSame($options, $this->request->getOptions());
     }
 
-    public function testParsingOptionDetails()
+    public function testParsingOptionDetails(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -125,7 +125,7 @@ public function testParsingOptionDetails()
         $this->assertNull($this->request->getOption('notthere'));
     }
 
-    public function testParsingOptionString()
+    public function testParsingOptionString(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -145,7 +145,7 @@ public function testParsingOptionString()
         $this->assertSame('--foo bar --baz "queue some stuff"', $this->request->getOptionString(true));
     }
 
-    public function testParsingNoOptions()
+    public function testParsingNoOptions(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -161,7 +161,7 @@ public function testParsingNoOptions()
         $this->assertSame($expected, $this->request->getOptionString());
     }
 
-    public function testParsingArgs()
+    public function testParsingArgs(): void
     {
         $_SERVER['argv'] = [
             'spark',
@@ -189,7 +189,7 @@ public function testParsingArgs()
         $this->assertSame($options, $this->request->getArgs());
     }
 
-    public function testParsingPath()
+    public function testParsingPath(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -206,7 +206,7 @@ public function testParsingPath()
         $this->assertSame('users/21/profile', $this->request->getPath());
     }
 
-    public function testParsingMalformed()
+    public function testParsingMalformed(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -227,7 +227,7 @@ public function testParsingMalformed()
         $this->assertSame('users/21/pro-file', $this->request->getPath());
     }
 
-    public function testParsingMalformed2()
+    public function testParsingMalformed2(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -248,7 +248,7 @@ public function testParsingMalformed2()
         $this->assertSame('users/21/profile', $this->request->getPath());
     }
 
-    public function testParsingMalformed3()
+    public function testParsingMalformed3(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -270,7 +270,7 @@ public function testParsingMalformed3()
         $this->assertSame('users/21/profile/bar', $this->request->getPath());
     }
 
-    public function testFetchGlobalsSingleValue()
+    public function testFetchGlobalsSingleValue(): void
     {
         $_POST['foo'] = 'bar';
         $_GET['bar']  = 'baz';
@@ -279,12 +279,12 @@ public function testFetchGlobalsSingleValue()
         $this->assertSame('baz', $this->request->fetchGlobal('get', 'bar'));
     }
 
-    public function testFetchGlobalsReturnsNullWhenNotFound()
+    public function testFetchGlobalsReturnsNullWhenNotFound(): void
     {
         $this->assertNull($this->request->fetchGlobal('post', 'foo'));
     }
 
-    public function testFetchGlobalsFiltersValues()
+    public function testFetchGlobalsFiltersValues(): void
     {
         $this->request->setGlobal('post', [
             'foo' => 'bar<script>',
@@ -295,7 +295,7 @@ public function testFetchGlobalsFiltersValues()
         $this->assertSame('baz', $this->request->fetchGlobal('post', 'bar'));
     }
 
-    public function testFetchGlobalsWithFilterFlag()
+    public function testFetchGlobalsWithFilterFlag(): void
     {
         $this->request->setGlobal('post', [
             'foo' => '`bar<script>',
@@ -306,7 +306,7 @@ public function testFetchGlobalsWithFilterFlag()
         $this->assertSame('baz', $this->request->fetchGlobal('post', 'bar'));
     }
 
-    public function testFetchGlobalReturnsAllWhenEmpty()
+    public function testFetchGlobalReturnsAllWhenEmpty(): void
     {
         $post = [
             'foo' => 'bar',
@@ -319,7 +319,7 @@ public function testFetchGlobalReturnsAllWhenEmpty()
         $this->assertSame($post, $this->request->fetchGlobal('post'));
     }
 
-    public function testFetchGlobalFiltersAllValues()
+    public function testFetchGlobalFiltersAllValues(): void
     {
         $post = [
             'foo' => 'bar<script>',
@@ -338,7 +338,7 @@ public function testFetchGlobalFiltersAllValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', null, FILTER_SANITIZE_ENCODED));
     }
 
-    public function testFetchGlobalFilterWithFlagAllValues()
+    public function testFetchGlobalFilterWithFlagAllValues(): void
     {
         $post = [
             'foo' => '`bar<script>',
@@ -357,7 +357,7 @@ public function testFetchGlobalFilterWithFlagAllValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', null, FILTER_SANITIZE_ENCODED, FILTER_FLAG_STRIP_BACKTICK));
     }
 
-    public function testFetchGlobalReturnsSelectedKeys()
+    public function testFetchGlobalReturnsSelectedKeys(): void
     {
         $post = [
             'foo' => 'bar',
@@ -374,7 +374,7 @@ public function testFetchGlobalReturnsSelectedKeys()
         $this->assertSame($expected, $this->request->fetchGlobal('post', ['foo', 'bar']));
     }
 
-    public function testFetchGlobalFiltersSelectedValues()
+    public function testFetchGlobalFiltersSelectedValues(): void
     {
         $post = [
             'foo' => 'bar<script>',
@@ -391,7 +391,7 @@ public function testFetchGlobalFiltersSelectedValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', ['foo', 'bar'], FILTER_SANITIZE_ENCODED));
     }
 
-    public function testFetchGlobalFilterWithFlagSelectedValues()
+    public function testFetchGlobalFilterWithFlagSelectedValues(): void
     {
         $post = [
             'foo' => '`bar<script>',
@@ -411,7 +411,7 @@ public function testFetchGlobalFilterWithFlagSelectedValues()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/353
      */
-    public function testFetchGlobalReturnsArrayValues()
+    public function testFetchGlobalReturnsArrayValues(): void
     {
         $post = [
             'ANNOUNCEMENTS' => [
@@ -432,7 +432,7 @@ public function testFetchGlobalReturnsArrayValues()
         $this->assertCount(2, $result['ANNOUNCEMENTS']);
     }
 
-    public function testFetchGlobalWithArrayTop()
+    public function testFetchGlobalWithArrayTop(): void
     {
         $post = [
             'clients' => [
@@ -446,7 +446,7 @@ public function testFetchGlobalWithArrayTop()
         $this->assertSame(['address' => ['zipcode' => 90210]], $this->request->fetchGlobal('post', 'clients'));
     }
 
-    public function testFetchGlobalWithArrayChildNumeric()
+    public function testFetchGlobalWithArrayChildNumeric(): void
     {
         $post = [
             'clients' => [
@@ -467,7 +467,7 @@ public function testFetchGlobalWithArrayChildNumeric()
         $this->assertSame(['zipcode' => 60610], $this->request->fetchGlobal('post', 'clients[1][address]'));
     }
 
-    public function testFetchGlobalWithArrayChildElement()
+    public function testFetchGlobalWithArrayChildElement(): void
     {
         $post = [
             'clients' => [
@@ -482,7 +482,7 @@ public function testFetchGlobalWithArrayChildElement()
         $this->assertNull($this->request->fetchGlobal('post', 'clients[zipcode]'));
     }
 
-    public function testFetchGlobalWithKeylessArrayChildElement()
+    public function testFetchGlobalWithKeylessArrayChildElement(): void
     {
         $post = [
             'clients' => [
@@ -497,7 +497,7 @@ public function testFetchGlobalWithKeylessArrayChildElement()
         $this->assertSame([['a']], $this->request->fetchGlobal('post', 'clients[stuff]'));
     }
 
-    public function testFetchGlobalWithArrayLastElement()
+    public function testFetchGlobalWithArrayLastElement(): void
     {
         $post = ['clients' => ['address' => ['zipcode' => 90210]]];
         $this->request->setGlobal('post', $post);
@@ -505,7 +505,7 @@ public function testFetchGlobalWithArrayLastElement()
         $this->assertSame('90210', $this->request->fetchGlobal('post', 'clients[address][zipcode]'));
     }
 
-    public function testFetchGlobalWithEmptyNotation()
+    public function testFetchGlobalWithEmptyNotation(): void
     {
         $expected = [
             ['address' => ['zipcode' => '90210']],
@@ -570,63 +570,63 @@ public function ipAddressChecks(): iterable
      * @param mixed      $address
      * @param mixed|null $type
      */
-    public function testValidIPAddress($expected, $address, $type = null)
+    public function testValidIPAddress($expected, $address, $type = null): void
     {
         $this->assertSame($expected, $this->request->isValidIP($address, $type));
     }
 
-    public function testGetIPAddressDefault()
+    public function testGetIPAddressDefault(): void
     {
         $this->assertSame('0.0.0.0', $this->request->getIPAddress());
     }
 
-    public function testMethodReturnsRightStuff()
+    public function testMethodReturnsRightStuff(): void
     {
         // Defaults method to CLI now.
         $this->assertSame('cli', $this->request->getMethod());
         $this->assertSame('CLI', $this->request->getMethod(true));
     }
 
-    public function testMethodIsCliReturnsAlwaysTrue()
+    public function testMethodIsCliReturnsAlwaysTrue(): void
     {
         $this->assertTrue($this->request->isCLI());
     }
 
-    public function testGetGet()
+    public function testGetGet(): void
     {
         $this->assertSame([], $this->request->getGet());
         $this->assertNull($this->request->getGet('test'));
         $this->assertSame([], $this->request->getGet(['test', 'abc']));
     }
 
-    public function testGetPost()
+    public function testGetPost(): void
     {
         $this->assertSame([], $this->request->getPost());
     }
 
-    public function testGetPostGet()
+    public function testGetPostGet(): void
     {
         $this->assertSame([], $this->request->getPostGet());
     }
 
-    public function testGetGetPost()
+    public function testGetGetPost(): void
     {
         $this->assertSame([], $this->request->getGetPost());
     }
 
-    public function testGetLocale()
+    public function testGetLocale(): void
     {
         $this->assertSame('en', $this->request->getLocale());
     }
 
-    public function testGetCookie()
+    public function testGetCookie(): void
     {
         $this->assertNull($this->request->getCookie('TESTY'));
 
         $this->assertSame($this->request->getCookie(), []);
     }
 
-    public function testIs()
+    public function testIs(): void
     {
         $this->assertFalse($this->request->is('get'));
     }
diff --git a/tests/system/HTTP/CURLRequestDoNotShareOptionsTest.php b/tests/system/HTTP/CURLRequestDoNotShareOptionsTest.php
index 7dcc47f40082..9399ed6a8f69 100644
--- a/tests/system/HTTP/CURLRequestDoNotShareOptionsTest.php
+++ b/tests/system/HTTP/CURLRequestDoNotShareOptionsTest.php
@@ -52,7 +52,7 @@ protected function getRequest(array $options = [])
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4707
      */
-    public function testPrepareURLIgnoresAppConfig()
+    public function testPrepareURLIgnoresAppConfig(): void
     {
         config('App')->baseURL = 'http://example.com/fruit/';
 
@@ -66,7 +66,7 @@ public function testPrepareURLIgnoresAppConfig()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1029
      */
-    public function testGetRemembersBaseURI()
+    public function testGetRemembersBaseURI(): void
     {
         $request = $this->getRequest(['base_uri' => 'http://www.foo.com/api/v1/']);
 
@@ -80,7 +80,7 @@ public function testGetRemembersBaseURI()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1029
      */
-    public function testGetRemembersBaseURIWithHelperMethod()
+    public function testGetRemembersBaseURIWithHelperMethod(): void
     {
         $request = Services::curlrequest(['base_uri' => 'http://www.foo.com/api/v1/']);
 
@@ -89,7 +89,7 @@ public function testGetRemembersBaseURIWithHelperMethod()
         $this->assertSame('/api/v1/', $uri->getPath());
     }
 
-    public function testSendReturnsResponse()
+    public function testSendReturnsResponse(): void
     {
         $output = 'Howdy Stranger.';
 
@@ -99,7 +99,7 @@ public function testSendReturnsResponse()
         $this->assertSame($output, $response->getBody());
     }
 
-    public function testGetSetsCorrectMethod()
+    public function testGetSetsCorrectMethod(): void
     {
         $this->request->get('http://example.com');
 
@@ -111,7 +111,7 @@ public function testGetSetsCorrectMethod()
         $this->assertSame('GET', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testDeleteSetsCorrectMethod()
+    public function testDeleteSetsCorrectMethod(): void
     {
         $this->request->delete('http://example.com');
 
@@ -123,7 +123,7 @@ public function testDeleteSetsCorrectMethod()
         $this->assertSame('DELETE', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testHeadSetsCorrectMethod()
+    public function testHeadSetsCorrectMethod(): void
     {
         $this->request->head('http://example.com');
 
@@ -135,7 +135,7 @@ public function testHeadSetsCorrectMethod()
         $this->assertSame('HEAD', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testOptionsSetsCorrectMethod()
+    public function testOptionsSetsCorrectMethod(): void
     {
         $this->request->options('http://example.com');
 
@@ -147,7 +147,7 @@ public function testOptionsSetsCorrectMethod()
         $this->assertSame('OPTIONS', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testOptionsBaseURIOption()
+    public function testOptionsBaseURIOption(): void
     {
         $options = ['base_uri' => 'http://www.foo.com/api/v1/'];
         $request = $this->getRequest($options);
@@ -155,7 +155,7 @@ public function testOptionsBaseURIOption()
         $this->assertSame('http://www.foo.com/api/v1/', $request->getBaseURI()->__toString());
     }
 
-    public function testOptionsBaseURIOverride()
+    public function testOptionsBaseURIOverride(): void
     {
         $options = [
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -166,7 +166,7 @@ public function testOptionsBaseURIOverride()
         $this->assertSame('http://bogus/com', $request->getBaseURI()->__toString());
     }
 
-    public function testOptionsHeaders()
+    public function testOptionsHeaders(): void
     {
         $options = [
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -182,7 +182,7 @@ public function testOptionsHeaders()
     /**
      * @backupGlobals enabled
      */
-    public function testOptionsHeadersNotUsingPopulate()
+    public function testOptionsHeadersNotUsingPopulate(): void
     {
         $_SERVER['HTTP_HOST']            = 'site1.com';
         $_SERVER['HTTP_ACCEPT_LANGUAGE'] = 'en-US';
@@ -203,7 +203,7 @@ public function testOptionsHeadersNotUsingPopulate()
         $this->assertSame('', $request->header('Accept-Encoding')->getValue());
     }
 
-    public function testDefaultOptionsAreSharedBetweenRequests()
+    public function testDefaultOptionsAreSharedBetweenRequests(): void
     {
         $options = [
             'form_params' => ['studio' => 1],
@@ -224,7 +224,7 @@ public function testDefaultOptionsAreSharedBetweenRequests()
         $this->assertSame('CodeIgniter Framework v4', $request->curl_options[CURLOPT_USERAGENT]);
     }
 
-    public function testHeaderContentLengthNotSharedBetweenRequests()
+    public function testHeaderContentLengthNotSharedBetweenRequests(): void
     {
         $options = [
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -244,7 +244,7 @@ public function testHeaderContentLengthNotSharedBetweenRequests()
     /**
      * @backupGlobals enabled
      */
-    public function testHeaderContentLengthNotSharedBetweenClients()
+    public function testHeaderContentLengthNotSharedBetweenClients(): void
     {
         $_SERVER['HTTP_CONTENT_LENGTH'] = '10';
 
@@ -264,7 +264,7 @@ public function testHeaderContentLengthNotSharedBetweenClients()
         $this->assertNull($request->header('Content-Length'));
     }
 
-    public function testOptionsDelay()
+    public function testOptionsDelay(): void
     {
         $request = $this->getRequest();
         $this->assertSame(0.0, $request->getDelay());
@@ -277,7 +277,7 @@ public function testOptionsDelay()
         $this->assertSame(2.0, $request->getDelay());
     }
 
-    public function testPatchSetsCorrectMethod()
+    public function testPatchSetsCorrectMethod(): void
     {
         $this->request->patch('http://example.com');
 
@@ -289,7 +289,7 @@ public function testPatchSetsCorrectMethod()
         $this->assertSame('PATCH', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testPostSetsCorrectMethod()
+    public function testPostSetsCorrectMethod(): void
     {
         $this->request->post('http://example.com');
 
@@ -301,7 +301,7 @@ public function testPostSetsCorrectMethod()
         $this->assertSame('POST', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testPutSetsCorrectMethod()
+    public function testPutSetsCorrectMethod(): void
     {
         $this->request->put('http://example.com');
 
@@ -313,7 +313,7 @@ public function testPutSetsCorrectMethod()
         $this->assertSame('PUT', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testCustomMethodSetsCorrectMethod()
+    public function testCustomMethodSetsCorrectMethod(): void
     {
         $this->request->request('custom', 'http://example.com');
 
@@ -325,7 +325,7 @@ public function testCustomMethodSetsCorrectMethod()
         $this->assertSame('CUSTOM', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testRequestMethodGetsSanitized()
+    public function testRequestMethodGetsSanitized(): void
     {
         $this->request->request('<script>Custom</script>', 'http://example.com');
 
@@ -337,7 +337,7 @@ public function testRequestMethodGetsSanitized()
         $this->assertSame('CUSTOM', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testRequestSetsBasicCurlOptions()
+    public function testRequestSetsBasicCurlOptions(): void
     {
         $this->request->request('get', 'http://example.com');
 
@@ -362,7 +362,7 @@ public function testRequestSetsBasicCurlOptions()
         $this->assertSame(150000.0, $options[CURLOPT_CONNECTTIMEOUT_MS]);
     }
 
-    public function testAuthBasicOption()
+    public function testAuthBasicOption(): void
     {
         $this->request->request('get', 'http://example.com', [
             'auth' => [
@@ -380,7 +380,7 @@ public function testAuthBasicOption()
         $this->assertSame(CURLAUTH_BASIC, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testAuthBasicOptionExplicit()
+    public function testAuthBasicOptionExplicit(): void
     {
         $this->request->request('get', 'http://example.com', [
             'auth' => [
@@ -399,7 +399,7 @@ public function testAuthBasicOptionExplicit()
         $this->assertSame(CURLAUTH_BASIC, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testAuthDigestOption()
+    public function testAuthDigestOption(): void
     {
         $output = "HTTP/1.1 401 Unauthorized
 		Server: ddos-guard
@@ -439,7 +439,7 @@ public function testAuthDigestOption()
         $this->assertSame(CURLAUTH_DIGEST, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testSetAuthBasic()
+    public function testSetAuthBasic(): void
     {
         $this->request->setAuth('username', 'password')->get('http://example.com');
 
@@ -452,7 +452,7 @@ public function testSetAuthBasic()
         $this->assertSame(CURLAUTH_BASIC, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testSetAuthDigest()
+    public function testSetAuthDigest(): void
     {
         $output = "HTTP/1.1 401 Unauthorized
 		Server: ddos-guard
@@ -486,7 +486,7 @@ public function testSetAuthDigest()
         $this->assertSame(CURLAUTH_DIGEST, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testCertOption()
+    public function testCertOption(): void
     {
         $file = __FILE__;
 
@@ -500,7 +500,7 @@ public function testCertOption()
         $this->assertSame($file, $options[CURLOPT_SSLCERT]);
     }
 
-    public function testCertOptionWithPassword()
+    public function testCertOptionWithPassword(): void
     {
         $file = __FILE__;
 
@@ -520,7 +520,7 @@ public function testCertOptionWithPassword()
         $this->assertSame('password', $options[CURLOPT_SSLCERTPASSWD]);
     }
 
-    public function testMissingCertOption()
+    public function testMissingCertOption(): void
     {
         $file = 'something_obviously_bogus';
         $this->expectException(HTTPException::class);
@@ -530,7 +530,7 @@ public function testMissingCertOption()
         ]);
     }
 
-    public function testSSLVerification()
+    public function testSSLVerification(): void
     {
         $file = __FILE__;
 
@@ -548,7 +548,7 @@ public function testSSLVerification()
         $this->assertSame(1, $options[CURLOPT_SSL_VERIFYPEER]);
     }
 
-    public function testSSLWithBadKey()
+    public function testSSLWithBadKey(): void
     {
         $file = 'something_obviously_bogus';
         $this->expectException(HTTPException::class);
@@ -559,7 +559,7 @@ public function testSSLWithBadKey()
         ]);
     }
 
-    public function testDebugOptionTrue()
+    public function testDebugOptionTrue(): void
     {
         $this->request->request('get', 'http://example.com', [
             'debug' => true,
@@ -574,7 +574,7 @@ public function testDebugOptionTrue()
         $this->assertIsResource($options[CURLOPT_STDERR]);
     }
 
-    public function testDebugOptionFalse()
+    public function testDebugOptionFalse(): void
     {
         $this->request->request('get', 'http://example.com', [
             'debug' => false,
@@ -586,7 +586,7 @@ public function testDebugOptionFalse()
         $this->assertArrayNotHasKey(CURLOPT_STDERR, $options);
     }
 
-    public function testDebugOptionFile()
+    public function testDebugOptionFile(): void
     {
         $file = SUPPORTPATH . 'Files/baker/banana.php';
 
@@ -603,7 +603,7 @@ public function testDebugOptionFile()
         $this->assertIsResource($options[CURLOPT_STDERR]);
     }
 
-    public function testDecodeContent()
+    public function testDecodeContent(): void
     {
         $this->request->setHeader('Accept-Encoding', 'cobol');
         $this->request->request('get', 'http://example.com', [
@@ -616,7 +616,7 @@ public function testDecodeContent()
         $this->assertSame('cobol', $options[CURLOPT_ENCODING]);
     }
 
-    public function testDecodeContentWithoutAccept()
+    public function testDecodeContentWithoutAccept(): void
     {
         //      $this->request->setHeader('Accept-Encoding', 'cobol');
         $this->request->request('get', 'http://example.com', [
@@ -631,7 +631,7 @@ public function testDecodeContentWithoutAccept()
         $this->assertSame('Accept-Encoding', $options[CURLOPT_HTTPHEADER]);
     }
 
-    public function testAllowRedirectsOptionFalse()
+    public function testAllowRedirectsOptionFalse(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => false,
@@ -646,7 +646,7 @@ public function testAllowRedirectsOptionFalse()
         $this->assertArrayNotHasKey(CURLOPT_REDIR_PROTOCOLS, $options);
     }
 
-    public function testAllowRedirectsOptionTrue()
+    public function testAllowRedirectsOptionTrue(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => true,
@@ -663,7 +663,7 @@ public function testAllowRedirectsOptionTrue()
         $this->assertSame(CURLPROTO_HTTP | CURLPROTO_HTTPS, $options[CURLOPT_REDIR_PROTOCOLS]);
     }
 
-    public function testAllowRedirectsOptionDefaults()
+    public function testAllowRedirectsOptionDefaults(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => true,
@@ -678,7 +678,7 @@ public function testAllowRedirectsOptionDefaults()
         $this->assertArrayHasKey(CURLOPT_REDIR_PROTOCOLS, $options);
     }
 
-    public function testAllowRedirectsArray()
+    public function testAllowRedirectsArray(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => ['max' => 2],
@@ -693,7 +693,7 @@ public function testAllowRedirectsArray()
         $this->assertSame(2, $options[CURLOPT_MAXREDIRS]);
     }
 
-    public function testSendWithQuery()
+    public function testSendWithQuery(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -710,7 +710,7 @@ public function testSendWithQuery()
         $this->assertSame('http://www.foo.com/api/v1/products?name=Henry&d.t=value', $options[CURLOPT_URL]);
     }
 
-    public function testSendWithDelay()
+    public function testSendWithDelay(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -723,7 +723,7 @@ public function testSendWithDelay()
         $this->assertSame(0.1, $request->getDelay());
     }
 
-    public function testSendContinued()
+    public function testSendContinued(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -738,7 +738,7 @@ public function testSendContinued()
     /**
      * See: https://github.com/codeigniter4/CodeIgniter4/issues/3261
      */
-    public function testSendContinuedWithManyHeaders()
+    public function testSendContinuedWithManyHeaders(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -785,7 +785,7 @@ public function testSendContinuedWithManyHeaders()
     /**
      * See: https://github.com/codeigniter4/CodeIgniter4/issues/7394
      */
-    public function testResponseHeadersWithMultipleRequests()
+    public function testResponseHeadersWithMultipleRequests(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -838,7 +838,7 @@ public function testResponseHeadersWithMultipleRequests()
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testSplitResponse()
+    public function testSplitResponse(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -850,7 +850,7 @@ public function testSplitResponse()
         $this->assertSame('Hi there', $response->getBody());
     }
 
-    public function testApplyBody()
+    public function testApplyBody(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -865,7 +865,7 @@ public function testApplyBody()
         $this->assertSame('name=George', $request->curl_options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testApplyBodyByOptions()
+    public function testApplyBodyByOptions(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -881,7 +881,7 @@ public function testApplyBodyByOptions()
         $this->assertSame('name=George', $request->curl_options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testBodyIsResetOnSecondRequest()
+    public function testBodyIsResetOnSecondRequest(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -896,7 +896,7 @@ public function testBodyIsResetOnSecondRequest()
         $this->assertArrayNotHasKey(CURLOPT_POSTFIELDS, $request->curl_options);
     }
 
-    public function testResponseHeaders()
+    public function testResponseHeaders(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -910,7 +910,7 @@ public function testResponseHeaders()
         $this->assertSame(234, $response->getStatusCode());
     }
 
-    public function testResponseHeadersShortProtocol()
+    public function testResponseHeadersShortProtocol(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -924,7 +924,7 @@ public function testResponseHeadersShortProtocol()
         $this->assertSame(235, $response->getStatusCode());
     }
 
-    public function testPostFormEncoded()
+    public function testPostFormEncoded(): void
     {
         $params = [
             'foo' => 'bar',
@@ -946,7 +946,7 @@ public function testPostFormEncoded()
         $this->assertSame($expected, $options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testPostFormMultipart()
+    public function testPostFormMultipart(): void
     {
         $params = [
             'foo' => 'bar',
@@ -968,7 +968,7 @@ public function testPostFormMultipart()
         $this->assertSame($params, $options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testSetForm()
+    public function testSetForm(): void
     {
         $params = [
             'foo' => 'bar',
@@ -995,7 +995,7 @@ public function testSetForm()
         );
     }
 
-    public function testJSONData()
+    public function testJSONData(): void
     {
         $params = [
             'foo' => 'bar',
@@ -1017,7 +1017,7 @@ public function testJSONData()
         );
     }
 
-    public function testSetJSON()
+    public function testSetJSON(): void
     {
         $params = [
             'foo' => 'bar',
@@ -1040,7 +1040,7 @@ public function testSetJSON()
         );
     }
 
-    public function testHTTPv1()
+    public function testHTTPv1(): void
     {
         $this->request->request('POST', '/post', [
             'version' => 1.0,
@@ -1052,7 +1052,7 @@ public function testHTTPv1()
         $this->assertSame(CURL_HTTP_VERSION_1_0, $options[CURLOPT_HTTP_VERSION]);
     }
 
-    public function testHTTPv11()
+    public function testHTTPv11(): void
     {
         $this->request->request('POST', '/post', [
             'version' => 1.1,
@@ -1064,7 +1064,7 @@ public function testHTTPv11()
         $this->assertSame(CURL_HTTP_VERSION_1_1, $options[CURLOPT_HTTP_VERSION]);
     }
 
-    public function testCookieOption()
+    public function testCookieOption(): void
     {
         $holder = SUPPORTPATH . 'HTTP/Files/CookiesHolder.txt';
         $this->request->request('POST', '/post', [
@@ -1079,7 +1079,7 @@ public function testCookieOption()
         $this->assertSame($holder, $options[CURLOPT_COOKIEFILE]);
     }
 
-    public function testUserAgentOption()
+    public function testUserAgentOption(): void
     {
         $agent = 'CodeIgniter Framework';
 
diff --git a/tests/system/HTTP/CURLRequestTest.php b/tests/system/HTTP/CURLRequestTest.php
index d90b8847cbb6..415032d19628 100644
--- a/tests/system/HTTP/CURLRequestTest.php
+++ b/tests/system/HTTP/CURLRequestTest.php
@@ -52,7 +52,7 @@ protected function getRequest(array $options = [])
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4707
      */
-    public function testPrepareURLIgnoresAppConfig()
+    public function testPrepareURLIgnoresAppConfig(): void
     {
         config('App')->baseURL = 'http://example.com/fruit/';
 
@@ -66,7 +66,7 @@ public function testPrepareURLIgnoresAppConfig()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1029
      */
-    public function testGetRemembersBaseURI()
+    public function testGetRemembersBaseURI(): void
     {
         $request = $this->getRequest(['base_uri' => 'http://www.foo.com/api/v1/']);
 
@@ -80,7 +80,7 @@ public function testGetRemembersBaseURI()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1029
      */
-    public function testGetRemembersBaseURIWithHelperMethod()
+    public function testGetRemembersBaseURIWithHelperMethod(): void
     {
         $request = Services::curlrequest(['base_uri' => 'http://www.foo.com/api/v1/']);
 
@@ -89,7 +89,7 @@ public function testGetRemembersBaseURIWithHelperMethod()
         $this->assertSame('/api/v1/', $uri->getPath());
     }
 
-    public function testSendReturnsResponse()
+    public function testSendReturnsResponse(): void
     {
         $output = 'Howdy Stranger.';
 
@@ -99,7 +99,7 @@ public function testSendReturnsResponse()
         $this->assertSame($output, $response->getBody());
     }
 
-    public function testGetSetsCorrectMethod()
+    public function testGetSetsCorrectMethod(): void
     {
         $this->request->get('http://example.com');
 
@@ -111,7 +111,7 @@ public function testGetSetsCorrectMethod()
         $this->assertSame('GET', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testDeleteSetsCorrectMethod()
+    public function testDeleteSetsCorrectMethod(): void
     {
         $this->request->delete('http://example.com');
 
@@ -123,7 +123,7 @@ public function testDeleteSetsCorrectMethod()
         $this->assertSame('DELETE', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testHeadSetsCorrectMethod()
+    public function testHeadSetsCorrectMethod(): void
     {
         $this->request->head('http://example.com');
 
@@ -135,7 +135,7 @@ public function testHeadSetsCorrectMethod()
         $this->assertSame('HEAD', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testOptionsSetsCorrectMethod()
+    public function testOptionsSetsCorrectMethod(): void
     {
         $this->request->options('http://example.com');
 
@@ -147,7 +147,7 @@ public function testOptionsSetsCorrectMethod()
         $this->assertSame('OPTIONS', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testOptionsBaseURIOption()
+    public function testOptionsBaseURIOption(): void
     {
         $options = ['base_uri' => 'http://www.foo.com/api/v1/'];
         $request = $this->getRequest($options);
@@ -155,7 +155,7 @@ public function testOptionsBaseURIOption()
         $this->assertSame('http://www.foo.com/api/v1/', $request->getBaseURI()->__toString());
     }
 
-    public function testOptionsBaseURIOverride()
+    public function testOptionsBaseURIOverride(): void
     {
         $options = [
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -166,7 +166,7 @@ public function testOptionsBaseURIOverride()
         $this->assertSame('http://bogus/com', $request->getBaseURI()->__toString());
     }
 
-    public function testOptionsHeaders()
+    public function testOptionsHeaders(): void
     {
         $options = [
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -182,7 +182,7 @@ public function testOptionsHeaders()
     /**
      * @backupGlobals enabled
      */
-    public function testOptionsHeadersNotUsingPopulate()
+    public function testOptionsHeadersNotUsingPopulate(): void
     {
         $_SERVER['HTTP_HOST']            = 'site1.com';
         $_SERVER['HTTP_ACCEPT_LANGUAGE'] = 'en-US';
@@ -203,7 +203,7 @@ public function testOptionsHeadersNotUsingPopulate()
         $this->assertSame('', $request->header('Accept-Encoding')->getValue());
     }
 
-    public function testOptionsAreSharedBetweenRequests()
+    public function testOptionsAreSharedBetweenRequests(): void
     {
         $options = [
             'form_params' => ['studio' => 1],
@@ -227,7 +227,7 @@ public function testOptionsAreSharedBetweenRequests()
     /**
      * @backupGlobals enabled
      */
-    public function testHeaderContentLengthNotSharedBetweenClients()
+    public function testHeaderContentLengthNotSharedBetweenClients(): void
     {
         $_SERVER['HTTP_CONTENT_LENGTH'] = '10';
 
@@ -247,7 +247,7 @@ public function testHeaderContentLengthNotSharedBetweenClients()
         $this->assertNull($request->header('Content-Length'));
     }
 
-    public function testOptionsDelay()
+    public function testOptionsDelay(): void
     {
         $request = $this->getRequest();
         $this->assertSame(0.0, $request->getDelay());
@@ -260,7 +260,7 @@ public function testOptionsDelay()
         $this->assertSame(2.0, $request->getDelay());
     }
 
-    public function testPatchSetsCorrectMethod()
+    public function testPatchSetsCorrectMethod(): void
     {
         $this->request->patch('http://example.com');
 
@@ -272,7 +272,7 @@ public function testPatchSetsCorrectMethod()
         $this->assertSame('PATCH', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testPostSetsCorrectMethod()
+    public function testPostSetsCorrectMethod(): void
     {
         $this->request->post('http://example.com');
 
@@ -284,7 +284,7 @@ public function testPostSetsCorrectMethod()
         $this->assertSame('POST', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testPutSetsCorrectMethod()
+    public function testPutSetsCorrectMethod(): void
     {
         $this->request->put('http://example.com');
 
@@ -296,7 +296,7 @@ public function testPutSetsCorrectMethod()
         $this->assertSame('PUT', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testCustomMethodSetsCorrectMethod()
+    public function testCustomMethodSetsCorrectMethod(): void
     {
         $this->request->request('custom', 'http://example.com');
 
@@ -308,7 +308,7 @@ public function testCustomMethodSetsCorrectMethod()
         $this->assertSame('CUSTOM', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testRequestMethodGetsSanitized()
+    public function testRequestMethodGetsSanitized(): void
     {
         $this->request->request('<script>Custom</script>', 'http://example.com');
 
@@ -320,7 +320,7 @@ public function testRequestMethodGetsSanitized()
         $this->assertSame('CUSTOM', $options[CURLOPT_CUSTOMREQUEST]);
     }
 
-    public function testRequestSetsBasicCurlOptions()
+    public function testRequestSetsBasicCurlOptions(): void
     {
         $this->request->request('get', 'http://example.com');
 
@@ -345,7 +345,7 @@ public function testRequestSetsBasicCurlOptions()
         $this->assertSame(150000.0, $options[CURLOPT_CONNECTTIMEOUT_MS]);
     }
 
-    public function testAuthBasicOption()
+    public function testAuthBasicOption(): void
     {
         $this->request->request('get', 'http://example.com', [
             'auth' => [
@@ -363,7 +363,7 @@ public function testAuthBasicOption()
         $this->assertSame(CURLAUTH_BASIC, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testAuthBasicOptionExplicit()
+    public function testAuthBasicOptionExplicit(): void
     {
         $this->request->request('get', 'http://example.com', [
             'auth' => [
@@ -382,7 +382,7 @@ public function testAuthBasicOptionExplicit()
         $this->assertSame(CURLAUTH_BASIC, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testAuthDigestOption()
+    public function testAuthDigestOption(): void
     {
         $output = "HTTP/1.1 401 Unauthorized
 		Server: ddos-guard
@@ -422,7 +422,7 @@ public function testAuthDigestOption()
         $this->assertSame(CURLAUTH_DIGEST, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testSetAuthBasic()
+    public function testSetAuthBasic(): void
     {
         $this->request->setAuth('username', 'password')->get('http://example.com');
 
@@ -435,7 +435,7 @@ public function testSetAuthBasic()
         $this->assertSame(CURLAUTH_BASIC, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testSetAuthDigest()
+    public function testSetAuthDigest(): void
     {
         $output = "HTTP/1.1 401 Unauthorized
 		Server: ddos-guard
@@ -469,7 +469,7 @@ public function testSetAuthDigest()
         $this->assertSame(CURLAUTH_DIGEST, $options[CURLOPT_HTTPAUTH]);
     }
 
-    public function testCertOption()
+    public function testCertOption(): void
     {
         $file = __FILE__;
 
@@ -483,7 +483,7 @@ public function testCertOption()
         $this->assertSame($file, $options[CURLOPT_SSLCERT]);
     }
 
-    public function testCertOptionWithPassword()
+    public function testCertOptionWithPassword(): void
     {
         $file = __FILE__;
 
@@ -503,7 +503,7 @@ public function testCertOptionWithPassword()
         $this->assertSame('password', $options[CURLOPT_SSLCERTPASSWD]);
     }
 
-    public function testMissingCertOption()
+    public function testMissingCertOption(): void
     {
         $file = 'something_obviously_bogus';
         $this->expectException(HTTPException::class);
@@ -513,7 +513,7 @@ public function testMissingCertOption()
         ]);
     }
 
-    public function testSSLVerification()
+    public function testSSLVerification(): void
     {
         $file = __FILE__;
 
@@ -531,7 +531,7 @@ public function testSSLVerification()
         $this->assertSame(1, $options[CURLOPT_SSL_VERIFYPEER]);
     }
 
-    public function testSSLWithBadKey()
+    public function testSSLWithBadKey(): void
     {
         $file = 'something_obviously_bogus';
         $this->expectException(HTTPException::class);
@@ -542,7 +542,7 @@ public function testSSLWithBadKey()
         ]);
     }
 
-    public function testDebugOptionTrue()
+    public function testDebugOptionTrue(): void
     {
         $this->request->request('get', 'http://example.com', [
             'debug' => true,
@@ -557,7 +557,7 @@ public function testDebugOptionTrue()
         $this->assertIsResource($options[CURLOPT_STDERR]);
     }
 
-    public function testDebugOptionFalse()
+    public function testDebugOptionFalse(): void
     {
         $this->request->request('get', 'http://example.com', [
             'debug' => false,
@@ -569,7 +569,7 @@ public function testDebugOptionFalse()
         $this->assertArrayNotHasKey(CURLOPT_STDERR, $options);
     }
 
-    public function testDebugOptionFile()
+    public function testDebugOptionFile(): void
     {
         $file = SUPPORTPATH . 'Files/baker/banana.php';
 
@@ -586,7 +586,7 @@ public function testDebugOptionFile()
         $this->assertIsResource($options[CURLOPT_STDERR]);
     }
 
-    public function testDecodeContent()
+    public function testDecodeContent(): void
     {
         $this->request->setHeader('Accept-Encoding', 'cobol');
         $this->request->request('get', 'http://example.com', [
@@ -599,7 +599,7 @@ public function testDecodeContent()
         $this->assertSame('cobol', $options[CURLOPT_ENCODING]);
     }
 
-    public function testDecodeContentWithoutAccept()
+    public function testDecodeContentWithoutAccept(): void
     {
         //      $this->request->setHeader('Accept-Encoding', 'cobol');
         $this->request->request('get', 'http://example.com', [
@@ -614,7 +614,7 @@ public function testDecodeContentWithoutAccept()
         $this->assertSame('Accept-Encoding', $options[CURLOPT_HTTPHEADER]);
     }
 
-    public function testAllowRedirectsOptionFalse()
+    public function testAllowRedirectsOptionFalse(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => false,
@@ -629,7 +629,7 @@ public function testAllowRedirectsOptionFalse()
         $this->assertArrayNotHasKey(CURLOPT_REDIR_PROTOCOLS, $options);
     }
 
-    public function testAllowRedirectsOptionTrue()
+    public function testAllowRedirectsOptionTrue(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => true,
@@ -646,7 +646,7 @@ public function testAllowRedirectsOptionTrue()
         $this->assertSame(CURLPROTO_HTTP | CURLPROTO_HTTPS, $options[CURLOPT_REDIR_PROTOCOLS]);
     }
 
-    public function testAllowRedirectsOptionDefaults()
+    public function testAllowRedirectsOptionDefaults(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => true,
@@ -661,7 +661,7 @@ public function testAllowRedirectsOptionDefaults()
         $this->assertArrayHasKey(CURLOPT_REDIR_PROTOCOLS, $options);
     }
 
-    public function testAllowRedirectsArray()
+    public function testAllowRedirectsArray(): void
     {
         $this->request->request('get', 'http://example.com', [
             'allow_redirects' => ['max' => 2],
@@ -676,7 +676,7 @@ public function testAllowRedirectsArray()
         $this->assertSame(2, $options[CURLOPT_MAXREDIRS]);
     }
 
-    public function testSendWithQuery()
+    public function testSendWithQuery(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -693,7 +693,7 @@ public function testSendWithQuery()
         $this->assertSame('http://www.foo.com/api/v1/products?name=Henry&d.t=value', $options[CURLOPT_URL]);
     }
 
-    public function testSendWithDelay()
+    public function testSendWithDelay(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -706,7 +706,7 @@ public function testSendWithDelay()
         $this->assertSame(0.1, $request->getDelay());
     }
 
-    public function testSendContinued()
+    public function testSendContinued(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -721,7 +721,7 @@ public function testSendContinued()
     /**
      * See: https://github.com/codeigniter4/CodeIgniter4/issues/3261
      */
-    public function testSendContinuedWithManyHeaders()
+    public function testSendContinuedWithManyHeaders(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -765,7 +765,7 @@ public function testSendContinuedWithManyHeaders()
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testSendProxied()
+    public function testSendProxied(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -783,7 +783,7 @@ public function testSendProxied()
     /**
      * See: https://github.com/codeigniter4/CodeIgniter4/issues/7394
      */
-    public function testResponseHeadersWithMultipleRequests()
+    public function testResponseHeadersWithMultipleRequests(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -836,7 +836,7 @@ public function testResponseHeadersWithMultipleRequests()
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testSplitResponse()
+    public function testSplitResponse(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -848,7 +848,7 @@ public function testSplitResponse()
         $this->assertSame('Hi there', $response->getBody());
     }
 
-    public function testApplyBody()
+    public function testApplyBody(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -863,7 +863,7 @@ public function testApplyBody()
         $this->assertSame('name=George', $request->curl_options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testApplyBodyByOptions()
+    public function testApplyBodyByOptions(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -879,7 +879,7 @@ public function testApplyBodyByOptions()
         $this->assertSame('name=George', $request->curl_options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testResponseHeaders()
+    public function testResponseHeaders(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -893,7 +893,7 @@ public function testResponseHeaders()
         $this->assertSame(234, $response->getStatusCode());
     }
 
-    public function testResponseHeadersShortProtocol()
+    public function testResponseHeadersShortProtocol(): void
     {
         $request = $this->getRequest([
             'base_uri' => 'http://www.foo.com/api/v1/',
@@ -907,7 +907,7 @@ public function testResponseHeadersShortProtocol()
         $this->assertSame(235, $response->getStatusCode());
     }
 
-    public function testPostFormEncoded()
+    public function testPostFormEncoded(): void
     {
         $params = [
             'foo' => 'bar',
@@ -929,7 +929,7 @@ public function testPostFormEncoded()
         $this->assertSame($expected, $options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testPostFormMultipart()
+    public function testPostFormMultipart(): void
     {
         $params = [
             'foo' => 'bar',
@@ -951,7 +951,7 @@ public function testPostFormMultipart()
         $this->assertSame($params, $options[CURLOPT_POSTFIELDS]);
     }
 
-    public function testSetForm()
+    public function testSetForm(): void
     {
         $params = [
             'foo' => 'bar',
@@ -978,7 +978,7 @@ public function testSetForm()
         );
     }
 
-    public function testJSONData()
+    public function testJSONData(): void
     {
         $params = [
             'foo' => 'bar',
@@ -997,7 +997,7 @@ public function testJSONData()
         $this->assertSame($expected, $this->request->getBody());
     }
 
-    public function testSetJSON()
+    public function testSetJSON(): void
     {
         $params = [
             'foo' => 'bar',
@@ -1015,7 +1015,7 @@ public function testSetJSON()
         );
     }
 
-    public function testHTTPv1()
+    public function testHTTPv1(): void
     {
         $this->request->request('POST', '/post', [
             'version' => 1.0,
@@ -1027,7 +1027,7 @@ public function testHTTPv1()
         $this->assertSame(CURL_HTTP_VERSION_1_0, $options[CURLOPT_HTTP_VERSION]);
     }
 
-    public function testHTTPv11()
+    public function testHTTPv11(): void
     {
         $this->request->request('POST', '/post', [
             'version' => 1.1,
@@ -1039,7 +1039,7 @@ public function testHTTPv11()
         $this->assertSame(CURL_HTTP_VERSION_1_1, $options[CURLOPT_HTTP_VERSION]);
     }
 
-    public function testHTTPv2()
+    public function testHTTPv2(): void
     {
         $this->request->request('POST', '/post', [
             'version' => 2.0,
@@ -1051,7 +1051,7 @@ public function testHTTPv2()
         $this->assertSame(CURL_HTTP_VERSION_2_0, $options[CURLOPT_HTTP_VERSION]);
     }
 
-    public function testCookieOption()
+    public function testCookieOption(): void
     {
         $holder = SUPPORTPATH . 'HTTP/Files/CookiesHolder.txt';
         $this->request->request('POST', '/post', [
@@ -1066,7 +1066,7 @@ public function testCookieOption()
         $this->assertSame($holder, $options[CURLOPT_COOKIEFILE]);
     }
 
-    public function testUserAgentOption()
+    public function testUserAgentOption(): void
     {
         $agent = 'CodeIgniter Framework';
 
diff --git a/tests/system/HTTP/ContentSecurityPolicyTest.php b/tests/system/HTTP/ContentSecurityPolicyTest.php
index 4b4d7a1a4975..81fd2d998602 100644
--- a/tests/system/HTTP/ContentSecurityPolicyTest.php
+++ b/tests/system/HTTP/ContentSecurityPolicyTest.php
@@ -32,7 +32,7 @@ final class ContentSecurityPolicyTest extends CIUnitTestCase
     private ?ContentSecurityPolicy $csp = null;
 
     // Having this method as setUp() doesn't work - can't find Config\App !?
-    protected function prepare(bool $CSPEnabled = true)
+    protected function prepare(bool $CSPEnabled = true): void
     {
         $this->resetServices();
 
@@ -63,7 +63,7 @@ protected function work(string $parm = 'Hello')
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testExistence()
+    public function testExistence(): void
     {
         $this->prepare();
         $this->work();
@@ -75,7 +75,7 @@ public function testExistence()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testReportOnly()
+    public function testReportOnly(): void
     {
         $this->prepare();
         $this->csp->reportOnly(false);
@@ -88,7 +88,7 @@ public function testReportOnly()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testDefaults()
+    public function testDefaults(): void
     {
         $this->prepare();
 
@@ -107,7 +107,7 @@ public function testDefaults()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testChildSrc()
+    public function testChildSrc(): void
     {
         $this->prepare();
         $this->csp->addChildSrc('evil.com', true);
@@ -124,7 +124,7 @@ public function testChildSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testConnectSrc()
+    public function testConnectSrc(): void
     {
         $this->prepare();
         $this->csp->reportOnly(true);
@@ -140,7 +140,7 @@ public function testConnectSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testFontSrc()
+    public function testFontSrc(): void
     {
         $this->prepare();
         $this->csp->reportOnly(true);
@@ -158,7 +158,7 @@ public function testFontSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testFormAction()
+    public function testFormAction(): void
     {
         $this->prepare();
         $this->csp->reportOnly(true);
@@ -176,7 +176,7 @@ public function testFormAction()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testFrameAncestor()
+    public function testFrameAncestor(): void
     {
         $this->prepare();
         $this->csp->addFrameAncestor('self');
@@ -193,7 +193,7 @@ public function testFrameAncestor()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testFrameSrc()
+    public function testFrameSrc(): void
     {
         $this->prepare();
         $this->csp->addFrameSrc('self');
@@ -210,7 +210,7 @@ public function testFrameSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testImageSrc()
+    public function testImageSrc(): void
     {
         $this->prepare();
         $this->csp->addImageSrc('cdn.cloudy.com');
@@ -227,7 +227,7 @@ public function testImageSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testMediaSrc()
+    public function testMediaSrc(): void
     {
         $this->prepare();
         $this->csp->addMediaSrc('self');
@@ -244,7 +244,7 @@ public function testMediaSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testManifestSrc()
+    public function testManifestSrc(): void
     {
         $this->prepare();
         $this->csp->addManifestSrc('cdn.cloudy.com');
@@ -261,7 +261,7 @@ public function testManifestSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testPluginType()
+    public function testPluginType(): void
     {
         $this->prepare();
         $this->csp->addPluginType('self');
@@ -278,7 +278,7 @@ public function testPluginType()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testPluginArray()
+    public function testPluginArray(): void
     {
         $this->prepare();
         $this->csp->addPluginType('application/x-shockwave-flash');
@@ -293,7 +293,7 @@ public function testPluginArray()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testObjectSrc()
+    public function testObjectSrc(): void
     {
         $this->prepare();
         $this->csp->addObjectSrc('cdn.cloudy.com');
@@ -310,7 +310,7 @@ public function testObjectSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testScriptSrc()
+    public function testScriptSrc(): void
     {
         $this->prepare();
         $this->csp->addScriptSrc('cdn.cloudy.com');
@@ -327,7 +327,7 @@ public function testScriptSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testStyleSrc()
+    public function testStyleSrc(): void
     {
         $this->prepare();
         $this->csp->addStyleSrc('cdn.cloudy.com');
@@ -344,7 +344,7 @@ public function testStyleSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testBaseURIDefault()
+    public function testBaseURIDefault(): void
     {
         $this->prepare();
         $result = $this->work();
@@ -357,7 +357,7 @@ public function testBaseURIDefault()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testBaseURI()
+    public function testBaseURI(): void
     {
         $this->prepare();
         $this->csp->addBaseURI('example.com');
@@ -371,7 +371,7 @@ public function testBaseURI()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testBaseURIRich()
+    public function testBaseURIRich(): void
     {
         $this->prepare();
         $this->csp->addBaseURI(['self', 'example.com']);
@@ -385,7 +385,7 @@ public function testBaseURIRich()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testDefaultSrc()
+    public function testDefaultSrc(): void
     {
         $this->prepare();
         $this->csp->reportOnly(false);
@@ -401,7 +401,7 @@ public function testDefaultSrc()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testReportURI()
+    public function testReportURI(): void
     {
         $this->prepare();
         $this->csp->reportOnly(false);
@@ -416,7 +416,7 @@ public function testReportURI()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSandboxFlags()
+    public function testSandboxFlags(): void
     {
         $this->prepare();
         $this->csp->reportOnly(false);
@@ -432,7 +432,7 @@ public function testSandboxFlags()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testUpgradeInsecureRequests()
+    public function testUpgradeInsecureRequests(): void
     {
         $this->prepare();
         $this->csp->upgradeInsecureRequests();
@@ -446,7 +446,7 @@ public function testUpgradeInsecureRequests()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testBodyEmpty()
+    public function testBodyEmpty(): void
     {
         $this->prepare();
         $body = '';
@@ -459,7 +459,7 @@ public function testBodyEmpty()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testBodyScriptNonce()
+    public function testBodyScriptNonce(): void
     {
         $this->prepare();
         $body = 'Blah blah {csp-script-nonce} blah blah';
@@ -478,7 +478,7 @@ public function testBodyScriptNonce()
         $this->assertSame([], $nonceStyle);
     }
 
-    public function testBodyScriptNonceCustomScriptTag()
+    public function testBodyScriptNonceCustomScriptTag(): void
     {
         $config                 = new CSPConfig();
         $config->scriptNonceTag = '{custom-script-nonce-tag}';
@@ -494,7 +494,7 @@ public function testBodyScriptNonceCustomScriptTag()
         $this->assertStringContainsString('nonce=', $response->getBody());
     }
 
-    public function testBodyScriptNonceDisableAutoNonce()
+    public function testBodyScriptNonceDisableAutoNonce(): void
     {
         $config            = new CSPConfig();
         $config->autoNonce = false;
@@ -513,7 +513,7 @@ public function testBodyScriptNonceDisableAutoNonce()
         $result->assertHeader('Content-Security-Policy');
     }
 
-    public function testBodyStyleNonceDisableAutoNonce()
+    public function testBodyStyleNonceDisableAutoNonce(): void
     {
         $config            = new CSPConfig();
         $config->autoNonce = false;
@@ -536,7 +536,7 @@ public function testBodyStyleNonceDisableAutoNonce()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testBodyStyleNonce()
+    public function testBodyStyleNonce(): void
     {
         $this->prepare();
         $body = 'Blah blah {csp-style-nonce} blah blah';
@@ -555,7 +555,7 @@ public function testBodyStyleNonce()
         $this->assertSame([], $nonceScript);
     }
 
-    public function testBodyStyleNonceCustomStyleTag()
+    public function testBodyStyleNonceCustomStyleTag(): void
     {
         $config                = new CSPConfig();
         $config->styleNonceTag = '{custom-style-nonce-tag}';
@@ -575,7 +575,7 @@ public function testBodyStyleNonceCustomStyleTag()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeaderWrongCaseNotFound()
+    public function testHeaderWrongCaseNotFound(): void
     {
         $this->prepare();
         $result = $this->work();
@@ -588,7 +588,7 @@ public function testHeaderWrongCaseNotFound()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeaderIgnoreCase()
+    public function testHeaderIgnoreCase(): void
     {
         $this->prepare();
         $result = $this->work();
@@ -601,7 +601,7 @@ public function testHeaderIgnoreCase()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testCSPDisabled()
+    public function testCSPDisabled(): void
     {
         $this->prepare(false);
         $this->work();
@@ -610,7 +610,7 @@ public function testCSPDisabled()
         $this->assertHeaderNotEmitted('content-security-policy', true);
     }
 
-    public function testGetScriptNonce()
+    public function testGetScriptNonce(): void
     {
         $this->prepare();
 
@@ -619,7 +619,7 @@ public function testGetScriptNonce()
         $this->assertMatchesRegularExpression('/\A[0-9a-z]{24}\z/', $nonce);
     }
 
-    public function testGetStyleNonce()
+    public function testGetStyleNonce(): void
     {
         $this->prepare();
 
@@ -632,7 +632,7 @@ public function testGetStyleNonce()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeaderScriptNonceEmittedOnceGetScriptNonceCalled()
+    public function testHeaderScriptNonceEmittedOnceGetScriptNonceCalled(): void
     {
         $this->prepare();
 
diff --git a/tests/system/HTTP/DownloadResponseTest.php b/tests/system/HTTP/DownloadResponseTest.php
index fe320705b290..6bd699375a63 100644
--- a/tests/system/HTTP/DownloadResponseTest.php
+++ b/tests/system/HTTP/DownloadResponseTest.php
@@ -31,14 +31,14 @@ protected function tearDown(): void
         }
     }
 
-    public function testCanGetStatusCode()
+    public function testCanGetStatusCode(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testCantSetStatusCode()
+    public function testCantSetStatusCode(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -46,7 +46,7 @@ public function testCantSetStatusCode()
         $response->setStatusCode(200);
     }
 
-    public function testSetDateRemembersDateInUTC()
+    public function testSetDateRemembersDateInUTC(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -61,7 +61,7 @@ public function testSetDateRemembersDateInUTC()
         $this->assertSame($date->format('D, d M Y H:i:s') . ' GMT', $header);
     }
 
-    public function testSetLastModifiedWithDateTimeObject()
+    public function testSetLastModifiedWithDateTimeObject(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -75,7 +75,7 @@ public function testSetLastModifiedWithDateTimeObject()
         $this->assertSame($date->format('D, d M Y H:i:s') . ' GMT', $header);
     }
 
-    public function testSetLastModifiedWithString()
+    public function testSetLastModifiedWithString(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -86,14 +86,14 @@ public function testSetLastModifiedWithString()
         $this->assertSame('2000-03-10 10:23:45', $header);
     }
 
-    public function testsentMethodSouldReturnRedirectResponse()
+    public function testsentMethodSouldReturnRedirectResponse(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
         $this->assertInstanceOf(DownloadResponse::class, $response);
     }
 
-    public function testSetContentType()
+    public function testSetContentType(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -102,7 +102,7 @@ public function testSetContentType()
         $this->assertSame('text/json; charset=UTF-8', $response->getHeaderLine('Content-Type'));
     }
 
-    public function testSetContentTypeNoCharSet()
+    public function testSetContentTypeNoCharSet(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -111,7 +111,7 @@ public function testSetContentTypeNoCharSet()
         $this->assertSame('application/octet-stream', $response->getHeaderLine('Content-Type'));
     }
 
-    public function testSetFileName()
+    public function testSetFileName(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
         $response->setFileName('myFile.txt');
@@ -120,7 +120,7 @@ public function testSetFileName()
         $this->assertSame('attachment; filename="myFile.txt"; filename*=UTF-8\'\'myFile.txt', $response->getHeaderLine('Content-Disposition'));
     }
 
-    public function testNoCache()
+    public function testNoCache(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -129,7 +129,7 @@ public function testNoCache()
         $this->assertSame('private, no-transform, no-store, must-revalidate', $response->getHeaderLine('Cache-control'));
     }
 
-    public function testCantSetCache()
+    public function testCantSetCache(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -137,7 +137,7 @@ public function testCantSetCache()
         $response->setCache();
     }
 
-    public function testWhenFilepathIsSetBinaryCanNotBeSet()
+    public function testWhenFilepathIsSetBinaryCanNotBeSet(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -146,7 +146,7 @@ public function testWhenFilepathIsSetBinaryCanNotBeSet()
         $response->setBinary('test');
     }
 
-    public function testWhenBinaryIsSetFilepathCanNotBeSet()
+    public function testWhenBinaryIsSetFilepathCanNotBeSet(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -155,7 +155,7 @@ public function testWhenBinaryIsSetFilepathCanNotBeSet()
         $response->setFilePath(__FILE__);
     }
 
-    public function testCanNotSetNoFilepath()
+    public function testCanNotSetNoFilepath(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -163,7 +163,7 @@ public function testCanNotSetNoFilepath()
         $response->setFilePath('unit test');
     }
 
-    public function testCanGetContentLength()
+    public function testCanGetContentLength(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -181,7 +181,7 @@ public function testCanGetContentLength()
         $this->assertSame($size, $response->getContentLength());
     }
 
-    public function testIsSetDownloadableHeadlersFromBinary()
+    public function testIsSetDownloadableHeadlersFromBinary(): void
     {
         $response = new DownloadResponse('unit test.txt', false);
 
@@ -195,7 +195,7 @@ public function testIsSetDownloadableHeadlersFromBinary()
         $this->assertSame('4', $response->getHeaderLine('Content-Length'));
     }
 
-    public function testIsSetDownloadableHeadlersFromFile()
+    public function testIsSetDownloadableHeadlersFromFile(): void
     {
         $response = new DownloadResponse('unit-test.php', false);
 
@@ -209,7 +209,7 @@ public function testIsSetDownloadableHeadlersFromFile()
         $this->assertSame(filesize(__FILE__), (int) $response->getHeaderLine('Content-Length'));
     }
 
-    public function testIfTheCharacterCodeIsOtherThanUtf8ReplaceItWithUtf8AndRawurlencode()
+    public function testIfTheCharacterCodeIsOtherThanUtf8ReplaceItWithUtf8AndRawurlencode(): void
     {
         $response = new DownloadResponse(mb_convert_encoding('テスト.php', 'Shift-JIS', 'UTF-8'), false);
 
@@ -220,7 +220,7 @@ public function testIfTheCharacterCodeIsOtherThanUtf8ReplaceItWithUtf8AndRawurle
         $this->assertSame('attachment; filename="' . mb_convert_encoding('テスト.php', 'Shift-JIS', 'UTF-8') . '"; filename*=UTF-8\'\'%E3%83%86%E3%82%B9%E3%83%88.php', $response->getHeaderLine('Content-Disposition'));
     }
 
-    public function testFileExtensionIsUpperCaseWhenAndroidOSIs2()
+    public function testFileExtensionIsUpperCaseWhenAndroidOSIs2(): void
     {
         $_SERVER['HTTP_USER_AGENT'] = 'Mozilla/5.0 (Linux; U; Android 2.0.3; ja-jp; SC-02C Build/IML74K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30';
         $response                   = new DownloadResponse('unit-test.php', false);
@@ -231,7 +231,7 @@ public function testFileExtensionIsUpperCaseWhenAndroidOSIs2()
         $this->assertSame('attachment; filename="unit-test.PHP"; filename*=UTF-8\'\'unit-test.PHP', $response->getHeaderLine('Content-Disposition'));
     }
 
-    public function testIsSetContentTypeFromFilename()
+    public function testIsSetContentTypeFromFilename(): void
     {
         $response = new DownloadResponse('unit-test.txt', true);
 
@@ -241,7 +241,7 @@ public function testIsSetContentTypeFromFilename()
         $this->assertSame('text/plain; charset=UTF-8', $response->getHeaderLine('Content-Type'));
     }
 
-    public function testCanOutputFileBodyFromBinary()
+    public function testCanOutputFileBodyFromBinary(): void
     {
         $response = new DownloadResponse('unit-test.txt', false);
 
@@ -255,7 +255,7 @@ public function testCanOutputFileBodyFromBinary()
         $this->assertSame('test', $actual);
     }
 
-    public function testCanOutputFileBodyFromFile()
+    public function testCanOutputFileBodyFromFile(): void
     {
         $response = new DownloadResponse('unit-test.php', false);
 
@@ -269,7 +269,7 @@ public function testCanOutputFileBodyFromFile()
         $this->assertSame(file_get_contents(__FILE__), $actual);
     }
 
-    public function testThrowExceptionWhenNoSetDownloadSource()
+    public function testThrowExceptionWhenNoSetDownloadSource(): void
     {
         $response = new DownloadResponse('unit-test.php', false);
 
@@ -277,13 +277,13 @@ public function testThrowExceptionWhenNoSetDownloadSource()
         $response->sendBody();
     }
 
-    public function testGetReason()
+    public function testGetReason(): void
     {
         $response = new DownloadResponse('unit-test.php', false);
         $this->assertSame('OK', $response->getReasonPhrase());
     }
 
-    public function testPretendOutput()
+    public function testPretendOutput(): void
     {
         $response = new DownloadResponse('unit-test.php', false);
         $response->pretend(true);
@@ -302,7 +302,7 @@ public function testPretendOutput()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testRealOutput()
+    public function testRealOutput(): void
     {
         $response = new DownloadResponse('unit-test.php', false);
         $response->pretend(false);
diff --git a/tests/system/HTTP/Files/FileCollectionTest.php b/tests/system/HTTP/Files/FileCollectionTest.php
index c9d2c0123acf..6c9983effb84 100644
--- a/tests/system/HTTP/Files/FileCollectionTest.php
+++ b/tests/system/HTTP/Files/FileCollectionTest.php
@@ -27,14 +27,14 @@ protected function setUp(): void
         $_FILES = [];
     }
 
-    public function testAllReturnsArrayWithNoFiles()
+    public function testAllReturnsArrayWithNoFiles(): void
     {
         $files = new FileCollection();
 
         $this->assertSame([], $files->all());
     }
 
-    public function testAllReturnsValidSingleFile()
+    public function testAllReturnsValidSingleFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -57,7 +57,7 @@ public function testAllReturnsValidSingleFile()
         $this->assertSame(124, $file->getSize());
     }
 
-    public function testAllReturnsValidMultipleFilesSameName()
+    public function testAllReturnsValidMultipleFilesSameName(): void
     {
         $_FILES = [
             'userfile' => [
@@ -99,7 +99,7 @@ public function testAllReturnsValidMultipleFilesSameName()
         $this->assertSame(124, $file->getSize());
     }
 
-    public function testAllReturnsValidMultipleFilesDifferentName()
+    public function testAllReturnsValidMultipleFilesDifferentName(): void
     {
         $_FILES = [
             'userfile1' => [
@@ -144,7 +144,7 @@ public function testAllReturnsValidMultipleFilesDifferentName()
         $this->assertSame(248, $file->getSize());
     }
 
-    public function testExtensionGuessing()
+    public function testExtensionGuessing(): void
     {
         $_FILES = [
             'userfile1' => [
@@ -218,7 +218,7 @@ public function testExtensionGuessing()
         $this->assertSame('zip', $file->guessExtension());
     }
 
-    public function testAllReturnsValidSingleFileNestedName()
+    public function testAllReturnsValidSingleFileNestedName(): void
     {
         $_FILES = [
             'userfile' => [
@@ -263,7 +263,7 @@ public function testAllReturnsValidSingleFileNestedName()
         $this->assertSame(124, $file->getSize());
     }
 
-    public function testHasFileWithSingleFile()
+    public function testHasFileWithSingleFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -281,7 +281,7 @@ public function testHasFileWithSingleFile()
         $this->assertFalse($collection->hasFile('foo'));
     }
 
-    public function testHasFileWithMultipleFilesWithDifferentNames()
+    public function testHasFileWithMultipleFilesWithDifferentNames(): void
     {
         $_FILES = [
             'userfile1' => [
@@ -306,7 +306,7 @@ public function testHasFileWithMultipleFilesWithDifferentNames()
         $this->assertTrue($collection->hasFile('userfile2'));
     }
 
-    public function testHasFileWithSingleFileNestedName()
+    public function testHasFileWithSingleFileNestedName(): void
     {
         $_FILES = [
             'userfile' => [
@@ -341,7 +341,7 @@ public function testHasFileWithSingleFileNestedName()
         $this->assertTrue($collection->hasFile('userfile.foo.bar'));
     }
 
-    public function testErrorString()
+    public function testErrorString(): void
     {
         $_FILES = [
             'userfile' => [
@@ -361,7 +361,7 @@ public function testErrorString()
         $this->assertSame($expected, $file->getErrorString());
     }
 
-    public function testErrorStringWithUnknownError()
+    public function testErrorStringWithUnknownError(): void
     {
         $_FILES = [
             'userfile' => [
@@ -381,7 +381,7 @@ public function testErrorStringWithUnknownError()
         $this->assertSame($expected, $file->getErrorString());
     }
 
-    public function testErrorStringWithNoError()
+    public function testErrorStringWithNoError(): void
     {
         $_FILES = [
             'userfile' => [
@@ -400,7 +400,7 @@ public function testErrorStringWithNoError()
         $this->assertSame($expected, $file->getErrorString());
     }
 
-    public function testError()
+    public function testError(): void
     {
         $_FILES = [
             'userfile' => [
@@ -418,7 +418,7 @@ public function testError()
         $this->assertSame(UPLOAD_ERR_INI_SIZE, $file->getError());
     }
 
-    public function testErrorWithUnknownError()
+    public function testErrorWithUnknownError(): void
     {
         $_FILES = [
             'userfile' => [
@@ -435,7 +435,7 @@ public function testErrorWithUnknownError()
         $this->assertSame(0, $file->getError());
     }
 
-    public function testErrorWithNoError()
+    public function testErrorWithNoError(): void
     {
         $_FILES = [
             'userfile' => [
@@ -453,7 +453,7 @@ public function testErrorWithNoError()
         $this->assertSame(UPLOAD_ERR_OK, $file->getError());
     }
 
-    public function testFileReturnsValidSingleFile()
+    public function testFileReturnsValidSingleFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -473,7 +473,7 @@ public function testFileReturnsValidSingleFile()
         $this->assertSame(124, $file->getSize());
     }
 
-    public function testFileNoExistSingleFile()
+    public function testFileNoExistSingleFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -490,7 +490,7 @@ public function testFileNoExistSingleFile()
         $this->AssertNull($file);
     }
 
-    public function testFileReturnValidMultipleFiles()
+    public function testFileReturnValidMultipleFiles(): void
     {
         $_FILES = [
             'userfile' => [
@@ -533,7 +533,7 @@ public function testFileReturnValidMultipleFiles()
         $this->assertSame(248, $file2->getSize());
     }
 
-    public function testFileWithMultipleFilesNestedName()
+    public function testFileWithMultipleFilesNestedName(): void
     {
         $_FILES = [
             'my-form' => [
@@ -599,7 +599,7 @@ public function testFileWithMultipleFilesNestedName()
         $this->assertSame(243, $file2->getSize());
     }
 
-    public function testDoesntHaveFile()
+    public function testDoesntHaveFile(): void
     {
         $_FILES = [
             'my-form' => [
@@ -652,7 +652,7 @@ public function testDoesntHaveFile()
         $this->assertNull($collection->getFile('my-form.detailz.avatars.0'));
     }
 
-    public function testGetFileMultipleHasNoFile()
+    public function testGetFileMultipleHasNoFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -683,7 +683,7 @@ public function testGetFileMultipleHasNoFile()
         $this->assertNull($files);
     }
 
-    public function testGetFileMultipleReturnValidDotNotationSyntax()
+    public function testGetFileMultipleReturnValidDotNotationSyntax(): void
     {
         $_FILES = [
             'my-form' => [
@@ -751,7 +751,7 @@ public function testGetFileMultipleReturnValidDotNotationSyntax()
         $this->assertSame(243, $files[1]->getSize());
     }
 
-    public function testGetFileMultipleReturnInvalidDotNotationSyntax()
+    public function testGetFileMultipleReturnInvalidDotNotationSyntax(): void
     {
         $_FILES = [
             'my-form' => [
@@ -789,7 +789,7 @@ public function testGetFileMultipleReturnInvalidDotNotationSyntax()
         $this->assertNull($files);
     }
 
-    public function testGetFileMultipleReturnValidMultipleFiles()
+    public function testGetFileMultipleReturnValidMultipleFiles(): void
     {
         $_FILES = [
             'userfile' => [
@@ -834,7 +834,7 @@ public function testGetFileMultipleReturnValidMultipleFiles()
         $this->assertSame('text/csv', $files[1]->getClientMimeType());
     }
 
-    public function testGetFileMultipleReturnInvalidSingleFile()
+    public function testGetFileMultipleReturnInvalidSingleFile(): void
     {
         $_FILES = [
             'userfile' => [
diff --git a/tests/system/HTTP/Files/FileMovingTest.php b/tests/system/HTTP/Files/FileMovingTest.php
index 2362d64296b7..5ec79796e136 100644
--- a/tests/system/HTTP/Files/FileMovingTest.php
+++ b/tests/system/HTTP/Files/FileMovingTest.php
@@ -60,7 +60,7 @@ protected function tearDown(): void
         }
     }
 
-    public function testMove()
+    public function testMove(): void
     {
         $finalFilename = 'fileA';
         $_FILES        = [
@@ -100,7 +100,7 @@ public function testMove()
         $this->assertTrue($this->root->hasChild('destination/' . $finalFilename . '_1.txt'));
     }
 
-    public function testMoveOverwriting()
+    public function testMoveOverwriting(): void
     {
         $finalFilename = 'file_with_delimiters_underscore';
         $_FILES        = [
@@ -150,7 +150,7 @@ public function testMoveOverwriting()
         $this->assertFileExists($destination . '/' . $finalFilename . '.txt');
     }
 
-    public function testMoved()
+    public function testMoved(): void
     {
         $finalFilename = 'fileA';
         $_FILES        = [
@@ -183,7 +183,7 @@ public function testMoved()
         $this->assertTrue($file->hasMoved());
     }
 
-    public function testStore()
+    public function testStore(): void
     {
         $finalFilename = 'fileA';
         $_FILES        = [
@@ -215,7 +215,7 @@ public function testStore()
         $this->assertSame($destination . '/fileA.txt', $path);
     }
 
-    public function testAlreadyMoved()
+    public function testAlreadyMoved(): void
     {
         $finalFilename = 'fileA';
         $_FILES        = [
@@ -246,7 +246,7 @@ public function testAlreadyMoved()
         }
     }
 
-    public function testInvalidFile()
+    public function testInvalidFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -267,7 +267,7 @@ public function testInvalidFile()
         $file->move($destination, $file->getName(), false);
     }
 
-    public function testFailedMoveBecauseOfWarning()
+    public function testFailedMoveBecauseOfWarning(): void
     {
         $_FILES = [
             'userfile' => [
@@ -293,7 +293,7 @@ public function testFailedMoveBecauseOfWarning()
         $file->move($destination, $file->getName(), false);
     }
 
-    public function testFailedMoveBecauseOfFalseReturned()
+    public function testFailedMoveBecauseOfFalseReturned(): void
     {
         $_FILES = [
             'userfile1' => [
@@ -363,7 +363,7 @@ function move_uploaded_file($filename, $destination, ?bool $setReturnValue = nul
     return $return;
 }
 
-function rrmdir($src)
+function rrmdir($src): void
 {
     $dir = opendir($src);
 
diff --git a/tests/system/HTTP/HeaderTest.php b/tests/system/HTTP/HeaderTest.php
index 43ccf91b3c26..34d6190ef2a6 100644
--- a/tests/system/HTTP/HeaderTest.php
+++ b/tests/system/HTTP/HeaderTest.php
@@ -22,7 +22,7 @@
  */
 final class HeaderTest extends CIUnitTestCase
 {
-    public function testHeaderStoresBasics()
+    public function testHeaderStoresBasics(): void
     {
         $name  = 'foo';
         $value = 'bar';
@@ -33,7 +33,7 @@ public function testHeaderStoresBasics()
         $this->assertSame($value, $header->getValue());
     }
 
-    public function testHeaderStoresBasicsWithNull()
+    public function testHeaderStoresBasicsWithNull(): void
     {
         $name  = 'foo';
         $value = null;
@@ -44,7 +44,7 @@ public function testHeaderStoresBasicsWithNull()
         $this->assertSame('', $header->getValue());
     }
 
-    public function testHeaderStoresBasicWithInt()
+    public function testHeaderStoresBasicWithInt(): void
     {
         $name  = 'foo';
         $value = 123;
@@ -55,7 +55,7 @@ public function testHeaderStoresBasicWithInt()
         $this->assertSame((string) $value, $header->getValue());
     }
 
-    public function testHeaderStoresBasicWithObject()
+    public function testHeaderStoresBasicWithObject(): void
     {
         $this->expectException(Error::class);
         $this->expectExceptionMessage('Object of class stdClass could not be converted to string');
@@ -66,7 +66,7 @@ public function testHeaderStoresBasicWithObject()
         new Header($name, $value);
     }
 
-    public function testHeaderStoresArrayValues()
+    public function testHeaderStoresArrayValues(): void
     {
         $name  = 'foo';
         $value = [
@@ -80,7 +80,7 @@ public function testHeaderStoresArrayValues()
         $this->assertSame($value, $header->getValue());
     }
 
-    public function testHeaderStoresArrayKeyValue()
+    public function testHeaderStoresArrayKeyValue(): void
     {
         $name  = 'foo';
         $value = [
@@ -94,7 +94,7 @@ public function testHeaderStoresArrayKeyValue()
         $this->assertSame('key=val', $header->getValueLine());
     }
 
-    public function testHeaderSetters()
+    public function testHeaderSetters(): void
     {
         $name  = 'foo';
         $value = [
@@ -114,7 +114,7 @@ public function testHeaderSetters()
         $this->assertSame($name . ': bar, 123', (string) $header);
     }
 
-    public function testHeaderAppendsValueSkippedForNull()
+    public function testHeaderAppendsValueSkippedForNull(): void
     {
         $name     = 'foo';
         $value    = 'bar';
@@ -128,7 +128,7 @@ public function testHeaderAppendsValueSkippedForNull()
         $this->assertSame($expected, $header->getValue());
     }
 
-    public function testHeaderConvertsSingleToArray()
+    public function testHeaderConvertsSingleToArray(): void
     {
         $name  = 'foo';
         $value = 'bar';
@@ -146,7 +146,7 @@ public function testHeaderConvertsSingleToArray()
         $this->assertSame($expected, $header->getValue());
     }
 
-    public function testHeaderPrependsValueSkippedForNull()
+    public function testHeaderPrependsValueSkippedForNull(): void
     {
         $name     = 'foo';
         $value    = 'bar';
@@ -160,7 +160,7 @@ public function testHeaderPrependsValueSkippedForNull()
         $this->assertSame($expected, $header->getValue());
     }
 
-    public function testHeaderPrependsValue()
+    public function testHeaderPrependsValue(): void
     {
         $name  = 'foo';
         $value = 'bar';
@@ -178,7 +178,7 @@ public function testHeaderPrependsValue()
         $this->assertSame($expected, $header->getValue());
     }
 
-    public function testHeaderLineSimple()
+    public function testHeaderLineSimple(): void
     {
         $name  = 'foo';
         $value = [
@@ -194,7 +194,7 @@ public function testHeaderLineSimple()
         $this->assertSame($expected, $header->getValueLine());
     }
 
-    public function testHeaderSetValueWithNullWillMarkAsEmptyString()
+    public function testHeaderSetValueWithNullWillMarkAsEmptyString(): void
     {
         $name     = 'foo';
         $expected = '';
@@ -206,7 +206,7 @@ public function testHeaderSetValueWithNullWillMarkAsEmptyString()
         $this->assertSame($expected, $header->getValueLine());
     }
 
-    public function testHeaderLineWithArrayValues()
+    public function testHeaderLineWithArrayValues(): void
     {
         $name = 'foo';
 
@@ -220,7 +220,7 @@ public function testHeaderLineWithArrayValues()
         $this->assertSame($expected, $header->getValueLine());
     }
 
-    public function testHeaderToStringShowsEntireHeader()
+    public function testHeaderToStringShowsEntireHeader(): void
     {
         $name = 'foo';
 
diff --git a/tests/system/HTTP/IncomingRequestDetectingTest.php b/tests/system/HTTP/IncomingRequestDetectingTest.php
index cd220cbe0987..481821dd922b 100644
--- a/tests/system/HTTP/IncomingRequestDetectingTest.php
+++ b/tests/system/HTTP/IncomingRequestDetectingTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void
         $this->request = new IncomingRequest(new App(), new URI($origin), null, new UserAgent());
     }
 
-    public function testPathDefault()
+    public function testPathDefault(): void
     {
         // /index.php/woot?code=good#pos
         $_SERVER['REQUEST_URI'] = '/index.php/woot';
@@ -46,7 +46,7 @@ public function testPathDefault()
         $this->assertSame($expected, $this->request->detectPath());
     }
 
-    public function testPathDefaultEmpty()
+    public function testPathDefaultEmpty(): void
     {
         // /
         $_SERVER['REQUEST_URI'] = '/';
@@ -56,7 +56,7 @@ public function testPathDefaultEmpty()
         $this->assertSame($expected, $this->request->detectPath());
     }
 
-    public function testPathRequestURI()
+    public function testPathRequestURI(): void
     {
         // /index.php/woot?code=good#pos
         $_SERVER['REQUEST_URI'] = '/index.php/woot';
@@ -66,7 +66,7 @@ public function testPathRequestURI()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathRequestURINested()
+    public function testPathRequestURINested(): void
     {
         // I'm not sure but this is a case of Apache config making such SERVER
         // values?
@@ -84,7 +84,7 @@ public function testPathRequestURINested()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathRequestURISubfolder()
+    public function testPathRequestURISubfolder(): void
     {
         // /ci/index.php/popcorn/woot?code=good#pos
         $_SERVER['REQUEST_URI'] = '/ci/index.php/popcorn/woot';
@@ -94,7 +94,7 @@ public function testPathRequestURISubfolder()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathRequestURINoIndex()
+    public function testPathRequestURINoIndex(): void
     {
         // /sub/example
         $_SERVER['REQUEST_URI'] = '/sub/example';
@@ -104,7 +104,7 @@ public function testPathRequestURINoIndex()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathRequestURINginx()
+    public function testPathRequestURINginx(): void
     {
         // /ci/index.php/woot?code=good#pos
         $_SERVER['REQUEST_URI'] = '/index.php/woot?code=good';
@@ -114,7 +114,7 @@ public function testPathRequestURINginx()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathRequestURINginxRedirecting()
+    public function testPathRequestURINginxRedirecting(): void
     {
         // /?/ci/index.php/woot
         $_SERVER['REQUEST_URI'] = '/?/ci/woot';
@@ -124,7 +124,7 @@ public function testPathRequestURINginxRedirecting()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathRequestURISuppressed()
+    public function testPathRequestURISuppressed(): void
     {
         // /woot?code=good#pos
         $_SERVER['REQUEST_URI'] = '/woot';
@@ -134,7 +134,7 @@ public function testPathRequestURISuppressed()
         $this->assertSame($expected, $this->request->detectPath('REQUEST_URI'));
     }
 
-    public function testPathQueryString()
+    public function testPathQueryString(): void
     {
         // /index.php?/ci/woot
         $_SERVER['REQUEST_URI']  = '/index.php?/ci/woot';
@@ -145,7 +145,7 @@ public function testPathQueryString()
         $this->assertSame($expected, $this->request->detectPath('QUERY_STRING'));
     }
 
-    public function testPathQueryStringWithQueryString()
+    public function testPathQueryStringWithQueryString(): void
     {
         // /index.php?/ci/woot?code=good#pos
         $_SERVER['REQUEST_URI']  = '/index.php?/ci/woot?code=good';
@@ -156,7 +156,7 @@ public function testPathQueryStringWithQueryString()
         $this->assertSame($expected, $this->request->detectPath('QUERY_STRING'));
     }
 
-    public function testPathQueryStringEmpty()
+    public function testPathQueryStringEmpty(): void
     {
         // /index.php?
         $_SERVER['REQUEST_URI']  = '/index.php?';
@@ -167,7 +167,7 @@ public function testPathQueryStringEmpty()
         $this->assertSame($expected, $this->request->detectPath('QUERY_STRING'));
     }
 
-    public function testPathPathInfo()
+    public function testPathPathInfo(): void
     {
         // /index.php/woot?code=good#pos
         $this->request->setGlobal('server', [
@@ -180,7 +180,7 @@ public function testPathPathInfo()
         $this->assertSame($expected, $this->request->detectPath('PATH_INFO'));
     }
 
-    public function testPathPathInfoGlobal()
+    public function testPathPathInfoGlobal(): void
     {
         // /index.php/woot?code=good#pos
         $this->request->setGlobal('server', [
diff --git a/tests/system/HTTP/IncomingRequestTest.php b/tests/system/HTTP/IncomingRequestTest.php
index b4ab3606ed8b..b8015fab933e 100644
--- a/tests/system/HTTP/IncomingRequestTest.php
+++ b/tests/system/HTTP/IncomingRequestTest.php
@@ -39,7 +39,7 @@ protected function setUp(): void
         $_POST = $_GET = $_SERVER = $_REQUEST = $_ENV = $_COOKIE = $_SESSION = [];
     }
 
-    public function testCanGrabRequestVars()
+    public function testCanGrabRequestVars(): void
     {
         $_REQUEST['TEST'] = 5;
 
@@ -47,7 +47,7 @@ public function testCanGrabRequestVars()
         $this->assertNull($this->request->getVar('TESTY'));
     }
 
-    public function testCanGrabGetVars()
+    public function testCanGrabGetVars(): void
     {
         $_GET['TEST'] = 5;
 
@@ -55,7 +55,7 @@ public function testCanGrabGetVars()
         $this->assertNull($this->request->getGet('TESTY'));
     }
 
-    public function testCanGrabPostVars()
+    public function testCanGrabPostVars(): void
     {
         $_POST['TEST'] = 5;
 
@@ -63,7 +63,7 @@ public function testCanGrabPostVars()
         $this->assertNull($this->request->getPost('TESTY'));
     }
 
-    public function testCanGrabPostBeforeGet()
+    public function testCanGrabPostBeforeGet(): void
     {
         $_POST['TEST'] = 5;
         $_GET['TEST']  = 3;
@@ -72,12 +72,12 @@ public function testCanGrabPostBeforeGet()
         $this->assertSame('3', $this->request->getGetPost('TEST'));
     }
 
-    public function testNoOldInput()
+    public function testNoOldInput(): void
     {
         $this->assertNull($this->request->getOldInput('name'));
     }
 
-    public function testCanGetOldInput()
+    public function testCanGetOldInput(): void
     {
         $_SESSION['_ci_old_input'] = [
             'get'  => ['one' => 'two'],
@@ -88,7 +88,7 @@ public function testCanGetOldInput()
         $this->assertSame('two', $this->request->getOldInput('one'));
     }
 
-    public function testCanGetOldInputDotted()
+    public function testCanGetOldInputDotted(): void
     {
         $_SESSION['_ci_old_input'] = [
             'get'  => ['apple' => ['name' => 'two']],
@@ -99,7 +99,7 @@ public function testCanGetOldInputDotted()
         $this->assertSame('two', $this->request->getOldInput('apple.name'));
     }
 
-    public function testMissingOldInput()
+    public function testMissingOldInput(): void
     {
         $_SESSION['_ci_old_input'] = [
             'get'  => ['apple' => ['name' => 'two']],
@@ -112,7 +112,7 @@ public function testMissingOldInput()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1492
      */
-    public function testCanGetOldInputArrayWithSESSION()
+    public function testCanGetOldInputArrayWithSESSION(): void
     {
         $_SESSION['_ci_old_input'] = [
             'get'  => ['apple' => ['name' => 'two']],
@@ -129,7 +129,7 @@ public function testCanGetOldInputArrayWithSESSION()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testCanGetOldInputArrayWithSessionService()
+    public function testCanGetOldInputArrayWithSessionService(): void
     {
         $locations = [
             'AB' => 'Alberta',
@@ -142,7 +142,7 @@ public function testCanGetOldInputArrayWithSessionService()
         $this->assertSame($locations, $this->request->getOldInput('location'));
     }
 
-    public function testCanGrabServerVars()
+    public function testCanGrabServerVars(): void
     {
         $server                   = $this->getPrivateProperty($this->request, 'globals');
         $server['server']['TEST'] = 5;
@@ -152,7 +152,7 @@ public function testCanGrabServerVars()
         $this->assertNull($this->request->getServer('TESTY'));
     }
 
-    public function testCanGrabEnvVars()
+    public function testCanGrabEnvVars(): void
     {
         $server                = $this->getPrivateProperty($this->request, 'globals');
         $server['env']['TEST'] = 5;
@@ -162,7 +162,7 @@ public function testCanGrabEnvVars()
         $this->assertNull($this->request->getEnv('TESTY'));
     }
 
-    public function testCanGrabCookieVars()
+    public function testCanGrabCookieVars(): void
     {
         $_COOKIE['TEST'] = 5;
 
@@ -170,7 +170,7 @@ public function testCanGrabCookieVars()
         $this->assertNull($this->request->getCookie('TESTY'));
     }
 
-    public function testStoresDefaultLocale()
+    public function testStoresDefaultLocale(): void
     {
         $config = new App();
 
@@ -178,7 +178,7 @@ public function testStoresDefaultLocale()
         $this->assertSame($config->defaultLocale, $this->request->getLocale());
     }
 
-    public function testSetLocaleSaves()
+    public function testSetLocaleSaves(): void
     {
         $config                   = new App();
         $config->supportedLocales = ['en', 'es'];
@@ -191,7 +191,7 @@ public function testSetLocaleSaves()
         $this->assertSame('en', $request->getLocale());
     }
 
-    public function testSetBadLocale()
+    public function testSetBadLocale(): void
     {
         $config                   = new App();
         $config->supportedLocales = ['en', 'es'];
@@ -207,7 +207,7 @@ public function testSetBadLocale()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2774
      */
-    public function testNegotiatesLocale()
+    public function testNegotiatesLocale(): void
     {
         $_SERVER['HTTP_ACCEPT_LANGUAGE'] = 'fr-FR; q=1.0, en; q=0.5';
 
@@ -222,7 +222,7 @@ public function testNegotiatesLocale()
         $this->assertSame('fr', $request->getLocale());
     }
 
-    public function testNegotiatesLocaleOnlyBroad()
+    public function testNegotiatesLocaleOnlyBroad(): void
     {
         $_SERVER['HTTP_ACCEPT_LANGUAGE'] = 'fr; q=1.0, en; q=0.5';
 
@@ -241,7 +241,7 @@ public function testNegotiatesLocaleOnlyBroad()
     // that is up to the NegotiateTest. These are only to make sure that the requests
     // flow through to the negotiator
 
-    public function testNegotiatesNot()
+    public function testNegotiatesNot(): void
     {
         $this->request->setHeader('Accept-Charset', 'iso-8859-5, unicode-1-1;q=0.8');
 
@@ -249,7 +249,7 @@ public function testNegotiatesNot()
         $this->request->negotiate('something bogus', ['iso-8859-5', 'unicode-1-1']);
     }
 
-    public function testNegotiatesCharset()
+    public function testNegotiatesCharset(): void
     {
         // $_SERVER['HTTP_ACCEPT_CHARSET'] = 'iso-8859-5, unicode-1-1;q=0.8';
         $this->request->setHeader('Accept-Charset', 'iso-8859-5, unicode-1-1;q=0.8');
@@ -260,7 +260,7 @@ public function testNegotiatesCharset()
         );
     }
 
-    public function testNegotiatesMedia()
+    public function testNegotiatesMedia(): void
     {
         $this->request->setHeader('Accept', 'text/plain; q=0.5, text/html, text/x-dvi; q=0.8, text/x-c');
         $this->assertSame(
@@ -269,19 +269,19 @@ public function testNegotiatesMedia()
         );
     }
 
-    public function testNegotiatesEncoding()
+    public function testNegotiatesEncoding(): void
     {
         $this->request->setHeader('Accept-Encoding', 'gzip;q=1.0, identity; q=0.4, compress;q=0.5');
         $this->assertSame('gzip', $this->request->negotiate('encoding', ['gzip', 'compress']));
     }
 
-    public function testNegotiatesLanguage()
+    public function testNegotiatesLanguage(): void
     {
         $this->request->setHeader('Accept-Language', 'da, en-gb;q=0.8, en;q=0.7');
         $this->assertSame('en', $this->request->negotiate('language', ['en', 'da']));
     }
 
-    public function testCanGrabGetRawJSON()
+    public function testCanGrabGetRawJSON(): void
     {
         $json = '{"code":1, "message":"ok"}';
 
@@ -295,7 +295,7 @@ public function testCanGrabGetRawJSON()
         $this->assertSame($expected, $request->getJSON(true));
     }
 
-    public function testCanGetAVariableFromJson()
+    public function testCanGetAVariableFromJson(): void
     {
         $jsonObj = [
             'foo'   => 'bar',
@@ -327,7 +327,7 @@ public function testCanGetAVariableFromJson()
         $this->assertNull($request->getJsonVar('null'));
     }
 
-    public function testGetJsonVarAsArray()
+    public function testGetJsonVarAsArray(): void
     {
         $jsonObj = [
             'baz' => [
@@ -358,7 +358,7 @@ public function testGetJsonVarAsArray()
         $this->assertNull($jsonVar['null']);
     }
 
-    public function testGetJsonVarCanFilter()
+    public function testGetJsonVarCanFilter(): void
     {
         $json = json_encode(['foo' => 'bar']);
 
@@ -370,7 +370,7 @@ public function testGetJsonVarCanFilter()
         $this->assertFalse($request->getJsonVar('foo', false, FILTER_VALIDATE_INT));
     }
 
-    public function testGetJsonVarCanFilterArray()
+    public function testGetJsonVarCanFilterArray(): void
     {
         $json = json_encode([
             'string'      => 'hello123world',
@@ -423,7 +423,7 @@ public function testGetJsonVarCanFilterArray()
         );
     }
 
-    public function testGetVarWorksWithJson()
+    public function testGetVarWorksWithJson(): void
     {
         $json = json_encode(['foo' => 'bar', 'fizz' => 'buzz']);
 
@@ -448,7 +448,7 @@ public function testGetVarWorksWithJson()
         $this->assertSame('buzz', $all->fizz);
     }
 
-    public function testGetVarWorksWithJsonAndGetParams()
+    public function testGetVarWorksWithJsonAndGetParams(): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/';
@@ -480,7 +480,7 @@ public function testGetVarWorksWithJsonAndGetParams()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5391
      */
-    public function testGetJsonVarReturnsNullFromNullBody()
+    public function testGetJsonVarReturnsNullFromNullBody(): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/';
@@ -490,7 +490,7 @@ public function testGetJsonVarReturnsNullFromNullBody()
         $this->assertNull($request->getJsonVar('myKey'));
     }
 
-    public function testgetJSONReturnsNullFromNullBody()
+    public function testgetJSONReturnsNullFromNullBody(): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/';
@@ -500,7 +500,7 @@ public function testgetJSONReturnsNullFromNullBody()
         $this->assertNull($request->getJSON());
     }
 
-    public function testCanGrabGetRawInput()
+    public function testCanGrabGetRawInput(): void
     {
         $rawstring = 'username=admin001&role=administrator&usepass=0';
 
@@ -606,7 +606,7 @@ public function provideRawInputVarChecks(): iterable
      * @param mixed  $filter
      * @param mixed  $flag
      */
-    public function testCanGrabGetRawInputVar($rawstring, $var, $expected, $filter, $flag)
+    public function testCanGrabGetRawInputVar($rawstring, $var, $expected, $filter, $flag): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/';
@@ -619,7 +619,7 @@ public function testCanGrabGetRawInputVar($rawstring, $var, $expected, $filter,
     /**
      * @dataProvider provideIsHTTPMethods
      */
-    public function testIsHTTPMethodLowerCase(string $value)
+    public function testIsHTTPMethodLowerCase(string $value): void
     {
         $request = $this->request->withMethod($value);
 
@@ -642,14 +642,14 @@ public function provideIsHTTPMethods(): iterable
     /**
      * @dataProvider provideIsHTTPMethods
      */
-    public function testIsHTTPMethodUpperCase(string $value)
+    public function testIsHTTPMethodUpperCase(string $value): void
     {
         $request = $this->request->withMethod($value);
 
         $this->assertTrue($request->is($value));
     }
 
-    public function testIsInvalidValue()
+    public function testIsInvalidValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('Unknown type: invalid');
@@ -659,50 +659,50 @@ public function testIsInvalidValue()
         $request->is('invalid');
     }
 
-    public function testIsJson()
+    public function testIsJson(): void
     {
         $request = $this->request->setHeader('Content-Type', 'application/json');
 
         $this->assertTrue($request->is('json'));
     }
 
-    public function testIsWithAjax()
+    public function testIsWithAjax(): void
     {
         $request = $this->request->setHeader('X-Requested-With', 'XMLHttpRequest');
 
         $this->assertTrue($request->is('ajax'));
     }
 
-    public function testIsCLI()
+    public function testIsCLI(): void
     {
         $this->assertFalse($this->request->isCLI());
     }
 
-    public function testIsAJAX()
+    public function testIsAJAX(): void
     {
         $this->request->appendHeader('X-Requested-With', 'XMLHttpRequest');
         $this->assertTrue($this->request->isAJAX());
     }
 
-    public function testIsSecure()
+    public function testIsSecure(): void
     {
         $_SERVER['HTTPS'] = 'on';
         $this->assertTrue($this->request->isSecure());
     }
 
-    public function testIsSecureFrontEnd()
+    public function testIsSecureFrontEnd(): void
     {
         $this->request->appendHeader('Front-End-Https', 'on');
         $this->assertTrue($this->request->isSecure());
     }
 
-    public function testIsSecureForwarded()
+    public function testIsSecureForwarded(): void
     {
         $this->request->appendHeader('X-Forwarded-Proto', 'https');
         $this->assertTrue($this->request->isSecure());
     }
 
-    public function testUserAgent()
+    public function testUserAgent(): void
     {
         $_SERVER['HTTP_USER_AGENT'] = 'Mozilla';
 
@@ -712,7 +712,7 @@ public function testUserAgent()
         $this->assertSame('Mozilla', $request->getUserAgent()->__toString());
     }
 
-    public function testFileCollectionFactory()
+    public function testFileCollectionFactory(): void
     {
         $_FILES = [
             'userfile' => [
@@ -734,7 +734,7 @@ public function testFileCollectionFactory()
         $this->assertSame(124, $file->getSize());
     }
 
-    public function testGetFileMultiple()
+    public function testGetFileMultiple(): void
     {
         $_FILES = [
             'userfile' => [
@@ -766,7 +766,7 @@ public function testGetFileMultiple()
         $this->assertSame(125, $gotit[1]->getSize());
     }
 
-    public function testGetFile()
+    public function testGetFile(): void
     {
         $_FILES = [
             'userfile' => [
@@ -782,7 +782,7 @@ public function testGetFile()
         $this->assertSame(124, $gotit->getSize());
     }
 
-    public function testSpoofing()
+    public function testSpoofing(): void
     {
         $this->request->setMethod('WINK');
         $this->assertSame('wink', $this->request->getMethod());
@@ -791,7 +791,7 @@ public function testSpoofing()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2839
      */
-    public function testGetPostEmpty()
+    public function testGetPostEmpty(): void
     {
         $_POST['TEST'] = '5';
         $_GET['TEST']  = '3';
@@ -799,19 +799,19 @@ public function testGetPostEmpty()
         $this->assertSame($_GET, $this->request->getGetPost());
     }
 
-    public function testPostGetSecondStream()
+    public function testPostGetSecondStream(): void
     {
         $_GET['get'] = '3';
         $this->assertSame($_GET, $this->request->getPostGet());
     }
 
-    public function testGetPostSecondStream()
+    public function testGetPostSecondStream(): void
     {
         $_POST['post'] = '5';
         $this->assertSame($_POST, $this->request->getGetPost());
     }
 
-    public function testGetPostSecondStreams()
+    public function testGetPostSecondStreams(): void
     {
         $_GET['get']   = '3';
         $_POST['post'] = '5';
@@ -819,7 +819,7 @@ public function testGetPostSecondStreams()
         $this->assertSame(array_merge($_POST, $_GET), $this->request->getGetPost());
     }
 
-    public function testWithFalseBody()
+    public function testWithFalseBody(): void
     {
         // Use `false` here to simulate file_get_contents returning a false value
         $request = new IncomingRequest(new App(), new URI(), false, new UserAgent());
@@ -831,7 +831,7 @@ public function testWithFalseBody()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3020
      */
-    public function testGetPostIndexNotExists()
+    public function testGetPostIndexNotExists(): void
     {
         $_POST['TEST'] = 5;
         $_GET['TEST']  = 3;
@@ -859,7 +859,7 @@ public function providePathChecks(): iterable
      * @param mixed $path
      * @param mixed $detectPath
      */
-    public function testExtensionPHP($path, $detectPath)
+    public function testExtensionPHP($path, $detectPath): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/';
@@ -870,7 +870,7 @@ public function testExtensionPHP($path, $detectPath)
         $this->assertSame($detectPath, $request->detectPath());
     }
 
-    public function testGetPath()
+    public function testGetPath(): void
     {
         $_SERVER['REQUEST_URI'] = '/index.php/fruits/banana';
         $_SERVER['SCRIPT_NAME'] = '/index.php';
@@ -880,7 +880,7 @@ public function testGetPath()
         $this->assertSame('fruits/banana', $request->getPath());
     }
 
-    public function testGetPathIsRelative()
+    public function testGetPathIsRelative(): void
     {
         $_SERVER['REQUEST_URI'] = '/sub/folder/index.php/fruits/banana';
         $_SERVER['SCRIPT_NAME'] = '/sub/folder/index.php';
@@ -890,7 +890,7 @@ public function testGetPathIsRelative()
         $this->assertSame('fruits/banana', $request->getPath());
     }
 
-    public function testGetPathStoresDetectedValue()
+    public function testGetPathStoresDetectedValue(): void
     {
         $_SERVER['REQUEST_URI'] = '/fruits/banana';
         $_SERVER['SCRIPT_NAME'] = '/index.php';
@@ -902,7 +902,7 @@ public function testGetPathStoresDetectedValue()
         $this->assertSame('fruits/banana', $request->getPath());
     }
 
-    public function testGetPathIsRediscovered()
+    public function testGetPathIsRediscovered(): void
     {
         $_SERVER['REQUEST_URI'] = '/fruits/banana';
         $_SERVER['SCRIPT_NAME'] = '/index.php';
@@ -915,7 +915,7 @@ public function testGetPathIsRediscovered()
         $this->assertSame('candy/snickers', $request->getPath());
     }
 
-    public function testSetPath()
+    public function testSetPath(): void
     {
         $request = new IncomingRequest(new App(), new URI(), null, new UserAgent());
         $this->assertSame('', $request->getPath());
@@ -924,7 +924,7 @@ public function testSetPath()
         $this->assertSame('foobar', $request->getPath());
     }
 
-    public function testSetPathUpdatesURI()
+    public function testSetPathUpdatesURI(): void
     {
         $request = new IncomingRequest(new App(), new URI(), null, new UserAgent());
 
@@ -933,7 +933,7 @@ public function testSetPathUpdatesURI()
         $this->assertSame('apples', $request->getUri()->getPath());
     }
 
-    public function testGetIPAddressNormal()
+    public function testGetIPAddressNormal(): void
     {
         $expected               = '123.123.123.123';
         $_SERVER['REMOTE_ADDR'] = $expected;
@@ -946,7 +946,7 @@ public function testGetIPAddressNormal()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxy()
+    public function testGetIPAddressThruProxy(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['HTTP_X_FORWARDED_FOR'] = $expected;
@@ -964,7 +964,7 @@ public function testGetIPAddressThruProxy()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyIPv6()
+    public function testGetIPAddressThruProxyIPv6(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['HTTP_X_FORWARDED_FOR'] = $expected;
@@ -981,7 +981,7 @@ public function testGetIPAddressThruProxyIPv6()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyInvalidIPAddress()
+    public function testGetIPAddressThruProxyInvalidIPAddress(): void
     {
         $_SERVER['HTTP_X_FORWARDED_FOR'] = '123.456.23.123';
         $expected                        = '10.0.1.200';
@@ -999,7 +999,7 @@ public function testGetIPAddressThruProxyInvalidIPAddress()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyInvalidIPAddressIPv6()
+    public function testGetIPAddressThruProxyInvalidIPAddressIPv6(): void
     {
         $_SERVER['HTTP_X_FORWARDED_FOR'] = '2001:xyz::1';
         $expected                        = '2001:db8::2:1';
@@ -1016,7 +1016,7 @@ public function testGetIPAddressThruProxyInvalidIPAddressIPv6()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyNotWhitelisted()
+    public function testGetIPAddressThruProxyNotWhitelisted(): void
     {
         $expected                        = '10.10.1.200';
         $_SERVER['REMOTE_ADDR']          = $expected;
@@ -1034,7 +1034,7 @@ public function testGetIPAddressThruProxyNotWhitelisted()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyNotWhitelistedIPv6()
+    public function testGetIPAddressThruProxyNotWhitelistedIPv6(): void
     {
         $expected                        = '2001:db8::2:2';
         $_SERVER['REMOTE_ADDR']          = $expected;
@@ -1051,7 +1051,7 @@ public function testGetIPAddressThruProxyNotWhitelistedIPv6()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxySubnet()
+    public function testGetIPAddressThruProxySubnet(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['HTTP_X_FORWARDED_FOR'] = $expected;
@@ -1066,7 +1066,7 @@ public function testGetIPAddressThruProxySubnet()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxySubnetIPv6()
+    public function testGetIPAddressThruProxySubnetIPv6(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['HTTP_X_FORWARDED_FOR'] = $expected;
@@ -1081,7 +1081,7 @@ public function testGetIPAddressThruProxySubnetIPv6()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyOutOfSubnet()
+    public function testGetIPAddressThruProxyOutOfSubnet(): void
     {
         $expected                        = '192.168.5.21';
         $_SERVER['REMOTE_ADDR']          = $expected;
@@ -1096,7 +1096,7 @@ public function testGetIPAddressThruProxyOutOfSubnet()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyOutOfSubnetIPv6()
+    public function testGetIPAddressThruProxyOutOfSubnetIPv6(): void
     {
         $expected                        = '2001:db8:1235:ffff:ffff:ffff:ffff:ffff';
         $_SERVER['REMOTE_ADDR']          = $expected;
@@ -1111,7 +1111,7 @@ public function testGetIPAddressThruProxyOutOfSubnetIPv6()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyBothIPv4AndIPv6()
+    public function testGetIPAddressThruProxyBothIPv4AndIPv6(): void
     {
         $expected                        = '2001:db8:1235:ffff:ffff:ffff:ffff:ffff';
         $_SERVER['REMOTE_ADDR']          = $expected;
@@ -1129,7 +1129,7 @@ public function testGetIPAddressThruProxyBothIPv4AndIPv6()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyInvalidConfigString()
+    public function testGetIPAddressThruProxyInvalidConfigString(): void
     {
         $this->expectException(TypeError::class);
 
@@ -1141,7 +1141,7 @@ public function testGetIPAddressThruProxyInvalidConfigString()
         $this->request->getIPAddress();
     }
 
-    public function testGetIPAddressThruProxyInvalidConfigArray()
+    public function testGetIPAddressThruProxyInvalidConfigArray(): void
     {
         $this->expectException(ConfigException::class);
         $this->expectExceptionMessage(
diff --git a/tests/system/HTTP/MessageTest.php b/tests/system/HTTP/MessageTest.php
index 86e870d3b073..67768aa7ea2c 100644
--- a/tests/system/HTTP/MessageTest.php
+++ b/tests/system/HTTP/MessageTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void
 
     // We can only test the headers retrieved from $_SERVER
     // This test might fail under apache.
-    public function testHeadersRetrievesHeaders()
+    public function testHeadersRetrievesHeaders(): void
     {
         $this->message->setHeader('Host', 'daisyduke.com');
         $this->message->setHeader('Referer', 'RoscoePekoTrain.com');
@@ -46,7 +46,7 @@ public function testHeadersRetrievesHeaders()
         $this->assertSame('RoscoePekoTrain.com', $headers['Referer']->getValue());
     }
 
-    public function testCanGrabSingleHeader()
+    public function testCanGrabSingleHeader(): void
     {
         $this->message->setHeader('Host', 'daisyduke.com');
 
@@ -56,7 +56,7 @@ public function testCanGrabSingleHeader()
         $this->assertSame('daisyduke.com', $header->getValue());
     }
 
-    public function testCaseInsensitiveheader()
+    public function testCaseInsensitiveheader(): void
     {
         $this->message->setHeader('Host', 'daisyduke.com');
 
@@ -64,7 +64,7 @@ public function testCaseInsensitiveheader()
         $this->assertSame('daisyduke.com', $this->message->header('HOST')->getValue());
     }
 
-    public function testCanSetHeaders()
+    public function testCanSetHeaders(): void
     {
         $this->message->setHeader('first', 'kiss');
         $this->message->setHeader('second', ['black', 'book']);
@@ -73,7 +73,7 @@ public function testCanSetHeaders()
         $this->assertSame(['black', 'book'], $this->message->header('Second')->getValue());
     }
 
-    public function testSetHeaderOverwritesPrevious()
+    public function testSetHeaderOverwritesPrevious(): void
     {
         $this->message->setHeader('Pragma', 'cache');
         $this->message->setHeader('Pragma', 'no-cache');
@@ -81,7 +81,7 @@ public function testSetHeaderOverwritesPrevious()
         $this->assertSame('no-cache', $this->message->header('Pragma')->getValue());
     }
 
-    public function testHeaderLineIsReadable()
+    public function testHeaderLineIsReadable(): void
     {
         $this->message->setHeader('Accept', ['json', 'html']);
         $this->message->setHeader('Host', 'daisyduke.com');
@@ -90,7 +90,7 @@ public function testHeaderLineIsReadable()
         $this->assertSame('daisyduke.com', $this->message->header('Host')->getValueLine());
     }
 
-    public function testCanRemoveHeader()
+    public function testCanRemoveHeader(): void
     {
         $this->message->setHeader('Host', 'daisyduke.com');
 
@@ -99,7 +99,7 @@ public function testCanRemoveHeader()
         $this->assertNull($this->message->header('host'));
     }
 
-    public function testCanAppendHeader()
+    public function testCanAppendHeader(): void
     {
         $this->message->setHeader('accept', ['json', 'html']);
 
@@ -108,7 +108,7 @@ public function testCanAppendHeader()
         $this->assertSame(['json', 'html', 'xml'], $this->message->header('accept')->getValue());
     }
 
-    public function testCanPrependHeader()
+    public function testCanPrependHeader(): void
     {
         $this->message->setHeader('accept', ['json', 'html']);
 
@@ -117,27 +117,27 @@ public function testCanPrependHeader()
         $this->assertSame(['xml', 'json', 'html'], $this->message->header('accept')->getValue());
     }
 
-    public function testSetProtocolWorks()
+    public function testSetProtocolWorks(): void
     {
         $this->message->setProtocolVersion('1.1');
 
         $this->assertSame('1.1', $this->message->getProtocolVersion());
     }
 
-    public function testSetProtocolWorksWithNonNumericVersion()
+    public function testSetProtocolWorksWithNonNumericVersion(): void
     {
         $this->message->setProtocolVersion('HTTP/1.1');
 
         $this->assertSame('1.1', $this->message->getProtocolVersion());
     }
 
-    public function testSetProtocolThrowsExceptionWithInvalidProtocol()
+    public function testSetProtocolThrowsExceptionWithInvalidProtocol(): void
     {
         $this->expectException(HTTPException::class);
         $this->message->setProtocolVersion('1.2');
     }
 
-    public function testBodyBasics()
+    public function testBodyBasics(): void
     {
         $body = 'a strange little fellow.';
 
@@ -146,7 +146,7 @@ public function testBodyBasics()
         $this->assertSame($body, $this->message->getBody());
     }
 
-    public function testAppendBody()
+    public function testAppendBody(): void
     {
         $this->message->setBody('moo');
 
@@ -155,14 +155,14 @@ public function testAppendBody()
         $this->assertSame("moo\n", $this->message->getBody());
     }
 
-    public function testSetHeaderReplacingHeader()
+    public function testSetHeaderReplacingHeader(): void
     {
         $this->message->setHeader('Accept', 'json');
 
         $this->assertSame('json', $this->message->getHeaderLine('Accept'));
     }
 
-    public function testSetHeaderDuplicateSettings()
+    public function testSetHeaderDuplicateSettings(): void
     {
         $this->message->setHeader('Accept', 'json');
         $this->message->setHeader('Accept', 'xml');
@@ -170,7 +170,7 @@ public function testSetHeaderDuplicateSettings()
         $this->assertSame('xml', $this->message->getHeaderLine('Accept'));
     }
 
-    public function testSetHeaderDuplicateSettingsInsensitive()
+    public function testSetHeaderDuplicateSettingsInsensitive(): void
     {
         $this->message->setHeader('Accept', 'json');
         $this->message->setHeader('accept', 'xml');
@@ -178,7 +178,7 @@ public function testSetHeaderDuplicateSettingsInsensitive()
         $this->assertSame('xml', $this->message->getHeaderLine('Accept'));
     }
 
-    public function testSetHeaderArrayValues()
+    public function testSetHeaderArrayValues(): void
     {
         $this->message->setHeader('Accept', ['json', 'html', 'xml']);
 
@@ -209,7 +209,7 @@ public function provideArrayHeaderValue(): iterable
      *
      * @param mixed $arrayHeaderValue
      */
-    public function testSetHeaderWithExistingArrayValuesAppendStringValue($arrayHeaderValue)
+    public function testSetHeaderWithExistingArrayValuesAppendStringValue($arrayHeaderValue): void
     {
         $this->message->setHeader('Accept', $arrayHeaderValue);
         $this->message->setHeader('Accept', 'xml');
@@ -222,7 +222,7 @@ public function testSetHeaderWithExistingArrayValuesAppendStringValue($arrayHead
      *
      * @param mixed $arrayHeaderValue
      */
-    public function testSetHeaderWithExistingArrayValuesAppendArrayValue($arrayHeaderValue)
+    public function testSetHeaderWithExistingArrayValuesAppendArrayValue($arrayHeaderValue): void
     {
         $this->message->setHeader('Accept', $arrayHeaderValue);
         $this->message->setHeader('Accept', ['xml']);
@@ -230,7 +230,7 @@ public function testSetHeaderWithExistingArrayValuesAppendArrayValue($arrayHeade
         $this->assertSame('json, html, xml', $this->message->getHeaderLine('Accept'));
     }
 
-    public function testSetHeaderWithExistingArrayValuesAppendNullValue()
+    public function testSetHeaderWithExistingArrayValuesAppendNullValue(): void
     {
         $this->message->setHeader('Accept', ['json', 'html', 'xml']);
         $this->message->setHeader('Accept', null);
@@ -238,7 +238,7 @@ public function testSetHeaderWithExistingArrayValuesAppendNullValue()
         $this->assertSame('json, html, xml', $this->message->getHeaderLine('Accept'));
     }
 
-    public function testPopulateHeadersWithoutContentType()
+    public function testPopulateHeadersWithoutContentType(): void
     {
         $original    = $_SERVER;
         $originalEnv = getenv('CONTENT_TYPE');
@@ -255,7 +255,7 @@ public function testPopulateHeadersWithoutContentType()
         $_SERVER = $original; // restore so code coverage doesn't break
     }
 
-    public function testPopulateHeadersWithoutHTTP()
+    public function testPopulateHeadersWithoutHTTP(): void
     {
         // fail path, if argument doesn't have the HTTP_*
         $original = $_SERVER;
@@ -272,7 +272,7 @@ public function testPopulateHeadersWithoutHTTP()
         $_SERVER = $original; // restore so code coverage doesn't break
     }
 
-    public function testPopulateHeadersKeyNotExists()
+    public function testPopulateHeadersKeyNotExists(): void
     {
         // Success path, if array key is not exists, assign empty string to it's value
         $original = $_SERVER;
@@ -288,7 +288,7 @@ public function testPopulateHeadersKeyNotExists()
         $_SERVER = $original; // restore so code coverage doesn't break
     }
 
-    public function testPopulateHeaders()
+    public function testPopulateHeaders(): void
     {
         // success path
         $original = $_SERVER;
diff --git a/tests/system/HTTP/NegotiateTest.php b/tests/system/HTTP/NegotiateTest.php
index 547b50ca8039..4323e80c2b42 100644
--- a/tests/system/HTTP/NegotiateTest.php
+++ b/tests/system/HTTP/NegotiateTest.php
@@ -33,7 +33,7 @@ protected function setUp(): void
         $this->negotiate = new Negotiate($this->request);
     }
 
-    public function testNegotiateMediaFindsHighestMatch()
+    public function testNegotiateMediaFindsHighestMatch(): void
     {
         $this->request->setHeader('Accept', 'text/plain; q=0.5, text/html, text/x-dvi; q=0.8, text/x-c');
         $this->negotiate->setRequest($this->request);
@@ -47,7 +47,7 @@ public function testNegotiateMediaFindsHighestMatch()
         $this->assertSame('text/md', $this->negotiate->media(['text/md']));
     }
 
-    public function testParseHeaderDeterminesCorrectPrecedence()
+    public function testParseHeaderDeterminesCorrectPrecedence(): void
     {
         $header = $this->negotiate->parseHeader('text/*, text/plain, text/plain;format=flowed, */*');
 
@@ -57,14 +57,14 @@ public function testParseHeaderDeterminesCorrectPrecedence()
         $this->assertSame('*/*', $header[3]['value']);
     }
 
-    public function testNegotiateMediaReturnsSupportedMatchWhenAsterisksInAvailable()
+    public function testNegotiateMediaReturnsSupportedMatchWhenAsterisksInAvailable(): void
     {
         $this->request->setHeader('Accept', 'image/*, text/*');
 
         $this->assertSame('text/plain', $this->negotiate->media(['text/plain']));
     }
 
-    public function testNegotiateMediaRecognizesMediaTypes()
+    public function testNegotiateMediaRecognizesMediaTypes(): void
     {
         // Image has a higher specificity, but is the wrong type...
         $this->request->setHeader('Accept', 'text/*, image/jpeg');
@@ -72,7 +72,7 @@ public function testNegotiateMediaRecognizesMediaTypes()
         $this->assertSame('text/plain', $this->negotiate->media(['text/plain']));
     }
 
-    public function testNegotiateMediaSupportsStrictMatching()
+    public function testNegotiateMediaSupportsStrictMatching(): void
     {
         // Image has a higher specificity, but is the wrong type...
         $this->request->setHeader('Accept', 'text/md, image/jpeg');
@@ -81,7 +81,7 @@ public function testNegotiateMediaSupportsStrictMatching()
         $this->assertSame('', $this->negotiate->media(['text/plain'], true));
     }
 
-    public function testAcceptCharsetMatchesBasics()
+    public function testAcceptCharsetMatchesBasics(): void
     {
         $this->request->setHeader('Accept-Charset', 'iso-8859-5, unicode-1-1;q=0.8');
 
@@ -92,12 +92,12 @@ public function testAcceptCharsetMatchesBasics()
         $this->assertSame('utf-8', $this->negotiate->charset(['iso-8859', 'unicode-1-2']));
     }
 
-    public function testNegotiateEncodingReturnsFirstIfNoAcceptHeaderExists()
+    public function testNegotiateEncodingReturnsFirstIfNoAcceptHeaderExists(): void
     {
         $this->assertSame('compress', $this->negotiate->encoding(['compress', 'gzip']));
     }
 
-    public function testNegotiatesEncodingBasics()
+    public function testNegotiatesEncodingBasics(): void
     {
         $this->request->setHeader('Accept-Encoding', 'gzip;q=1.0, identity; q=0.4, compress;q=0.5');
 
@@ -106,7 +106,7 @@ public function testNegotiatesEncodingBasics()
         $this->assertSame('identity', $this->negotiate->encoding());
     }
 
-    public function testAcceptLanguageBasics()
+    public function testAcceptLanguageBasics(): void
     {
         $this->request->setHeader('Accept-Language', 'da, en-gb;q=0.8, en;q=0.7');
 
@@ -118,47 +118,47 @@ public function testAcceptLanguageBasics()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2774
      */
-    public function testAcceptLanguageMatchesBroadly()
+    public function testAcceptLanguageMatchesBroadly(): void
     {
         $this->request->setHeader('Accept-Language', 'fr-FR,fr;q=0.9,en-US;q=0.8,en;q=0.7');
 
         $this->assertSame('fr', $this->negotiate->language(['fr', 'en']));
     }
 
-    public function testBestMatchEmpty()
+    public function testBestMatchEmpty(): void
     {
         $this->expectException(HTTPException::class);
         $this->negotiate->media([]);
     }
 
-    public function testBestMatchNoHeader()
+    public function testBestMatchNoHeader(): void
     {
         $this->request->setHeader('Accept', '');
         $this->assertSame('', $this->negotiate->media(['apple', 'banana'], true));
         $this->assertSame('apple/mac', $this->negotiate->media(['apple/mac', 'banana/yellow'], false));
     }
 
-    public function testBestMatchNotAcceptable()
+    public function testBestMatchNotAcceptable(): void
     {
         $this->request->setHeader('Accept', 'popcorn/cheddar');
         $this->assertSame('apple/mac', $this->negotiate->media(['apple/mac', 'banana/yellow'], false));
         $this->assertSame('banana/yellow', $this->negotiate->media(['banana/yellow', 'apple/mac'], false));
     }
 
-    public function testBestMatchFirstSupported()
+    public function testBestMatchFirstSupported(): void
     {
         $this->request->setHeader('Accept', 'popcorn/cheddar, */*');
         $this->assertSame('apple/mac', $this->negotiate->media(['apple/mac', 'banana/yellow'], false));
     }
 
-    public function testBestMatchLowQuality()
+    public function testBestMatchLowQuality(): void
     {
         $this->request->setHeader('Accept', 'popcorn/cheddar;q=0, apple/mac, */*');
         $this->assertSame('apple/mac', $this->negotiate->media(['apple/mac', 'popcorn/cheddar'], false));
         $this->assertSame('apple/mac', $this->negotiate->media(['popcorn/cheddar', 'apple/mac'], false));
     }
 
-    public function testBestMatchOnlyLowQuality()
+    public function testBestMatchOnlyLowQuality(): void
     {
         $this->request->setHeader('Accept', 'popcorn/cheddar;q=0');
         // the first supported should be returned, since nothing will make us happy
@@ -166,7 +166,7 @@ public function testBestMatchOnlyLowQuality()
         $this->assertSame('popcorn/cheddar', $this->negotiate->media(['popcorn/cheddar', 'apple/mac'], false));
     }
 
-    public function testParameterMatching()
+    public function testParameterMatching(): void
     {
         $this->request->setHeader('Accept', 'popcorn/cheddar;a=0;b=1');
         $this->assertSame('popcorn/cheddar;a=2', $this->negotiate->media(['popcorn/cheddar;a=2'], false));
diff --git a/tests/system/HTTP/OutgoingRequestTest.php b/tests/system/HTTP/OutgoingRequestTest.php
index 8a6690772fa4..51b2bab6a3fe 100644
--- a/tests/system/HTTP/OutgoingRequestTest.php
+++ b/tests/system/HTTP/OutgoingRequestTest.php
@@ -20,7 +20,7 @@
  */
 final class OutgoingRequestTest extends CIUnitTestCase
 {
-    public function testCreateWithHeader()
+    public function testCreateWithHeader(): void
     {
         $uri     = new URI('https://example.com/');
         $headers = ['User-Agent' => 'Mozilla/5.0'];
@@ -29,7 +29,7 @@ public function testCreateWithHeader()
         $this->assertSame('Mozilla/5.0', $request->header('User-Agent')->getValue());
     }
 
-    public function testGetUri()
+    public function testGetUri(): void
     {
         $uri     = new URI('https://example.com/');
         $request = new OutgoingRequest('GET', $uri);
@@ -37,7 +37,7 @@ public function testGetUri()
         $this->assertSame($uri, $request->getUri());
     }
 
-    public function testWithMethod()
+    public function testWithMethod(): void
     {
         $uri     = new URI('https://example.com/');
         $request = new OutgoingRequest('GET', $uri);
@@ -48,7 +48,7 @@ public function testWithMethod()
         $this->assertSame('POST', strtoupper($newRequest->getMethod()));
     }
 
-    public function testWithUri()
+    public function testWithUri(): void
     {
         $uri     = new URI('https://example.com/');
         $request = new OutgoingRequest('GET', $uri);
@@ -65,7 +65,7 @@ public function testWithUri()
      *   request.
      * https://www.php-fig.org/psr/psr-7/#32-psrhttpmessagerequestinterface
      */
-    public function testWithUriPreserveHostHostHeaderIsMissingAndNewUriContainsHost()
+    public function testWithUriPreserveHostHostHeaderIsMissingAndNewUriContainsHost(): void
     {
         $uri     = new URI();
         $request = new OutgoingRequest('GET', $uri);
@@ -82,7 +82,7 @@ public function testWithUriPreserveHostHostHeaderIsMissingAndNewUriContainsHost(
      *   request.
      * https://www.php-fig.org/psr/psr-7/#32-psrhttpmessagerequestinterface
      */
-    public function testWithUriPreserveHostHostHeaderIsMissingAndNewUriDoesNotContainsHost()
+    public function testWithUriPreserveHostHostHeaderIsMissingAndNewUriDoesNotContainsHost(): void
     {
         $uri     = new URI();
         $request = new OutgoingRequest('GET', $uri);
@@ -98,7 +98,7 @@ public function testWithUriPreserveHostHostHeaderIsMissingAndNewUriDoesNotContai
      *   the Host header in the returned request.
      * https://www.php-fig.org/psr/psr-7/#32-psrhttpmessagerequestinterface
      */
-    public function testWithUriPreserveHostHostHostIsNonEmpty()
+    public function testWithUriPreserveHostHostHostIsNonEmpty(): void
     {
         $uri     = new URI('https://example.com/');
         $request = new OutgoingRequest('GET', $uri);
diff --git a/tests/system/HTTP/RedirectResponseTest.php b/tests/system/HTTP/RedirectResponseTest.php
index 5f95b307d8cf..c775da828865 100644
--- a/tests/system/HTTP/RedirectResponseTest.php
+++ b/tests/system/HTTP/RedirectResponseTest.php
@@ -59,7 +59,7 @@ protected function setUp(): void
         Services::injectMock('request', $this->request);
     }
 
-    public function testRedirectToFullURI()
+    public function testRedirectToFullURI(): void
     {
         $response = new RedirectResponse(new App());
 
@@ -69,7 +69,7 @@ public function testRedirectToFullURI()
         $this->assertSame('http://example.com/foo', $response->getHeaderLine('Location'));
     }
 
-    public function testRedirectRoute()
+    public function testRedirectRoute(): void
     {
         $response = new RedirectResponse(new App());
 
@@ -88,7 +88,7 @@ public function testRedirectRoute()
         $this->assertSame('http://example.com/index.php/exampleRoute2', $response->getHeaderLine('Location'));
     }
 
-    public function testRedirectRouteBadNamedRoute()
+    public function testRedirectRouteBadNamedRoute(): void
     {
         $this->expectException(HTTPException::class);
         $this->expectExceptionMessage('The route for "differentRoute" cannot be found.');
@@ -100,7 +100,7 @@ public function testRedirectRouteBadNamedRoute()
         $response->route('differentRoute');
     }
 
-    public function testRedirectRouteBadControllerMethod()
+    public function testRedirectRouteBadControllerMethod(): void
     {
         $this->expectException(HTTPException::class);
         $this->expectExceptionMessage('The route for "Bad::badMethod" cannot be found.');
@@ -112,7 +112,7 @@ public function testRedirectRouteBadControllerMethod()
         $response->route('Bad::badMethod');
     }
 
-    public function testRedirectRelativeConvertsToFullURI()
+    public function testRedirectRelativeConvertsToFullURI(): void
     {
         $response = new RedirectResponse($this->config);
 
@@ -126,7 +126,7 @@ public function testRedirectRelativeConvertsToFullURI()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testWithInput()
+    public function testWithInput(): void
     {
         $_SESSION = [];
         $_GET     = ['foo' => 'bar'];
@@ -146,7 +146,7 @@ public function testWithInput()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testWithValidationErrors()
+    public function testWithValidationErrors(): void
     {
         $_SESSION = [];
 
@@ -166,7 +166,7 @@ public function testWithValidationErrors()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testWith()
+    public function testWith(): void
     {
         $_SESSION = [];
 
@@ -182,7 +182,7 @@ public function testWith()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testRedirectBack()
+    public function testRedirectBack(): void
     {
         $_SERVER['HTTP_REFERER'] = 'http://somewhere.com';
         $this->request           = new MockIncomingRequest($this->config, new URI('http://somewhere.com'), null, new UserAgent());
@@ -198,7 +198,7 @@ public function testRedirectBack()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testRedirectBackMissing()
+    public function testRedirectBackMissing(): void
     {
         $_SESSION = [];
 
@@ -215,7 +215,7 @@ public function testRedirectBackMissing()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2119
      */
-    public function testRedirectRouteBaseUrl()
+    public function testRedirectRouteBaseUrl(): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/test/';
@@ -236,7 +236,7 @@ public function testRedirectRouteBaseUrl()
         Factories::reset('config');
     }
 
-    public function testWithCookies()
+    public function testWithCookies(): void
     {
         $_SESSION = [];
 
@@ -254,7 +254,7 @@ public function testWithCookies()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testWithCookiesWithEmptyCookies()
+    public function testWithCookiesWithEmptyCookies(): void
     {
         $_SESSION = [];
 
@@ -264,7 +264,7 @@ public function testWithCookiesWithEmptyCookies()
         $this->assertEmpty($response->getCookies());
     }
 
-    public function testWithHeaders()
+    public function testWithHeaders(): void
     {
         $_SESSION = [];
 
@@ -282,7 +282,7 @@ public function testWithHeaders()
         }
     }
 
-    public function testWithHeadersWithEmptyHeaders()
+    public function testWithHeadersWithEmptyHeaders(): void
     {
         $_SESSION = [];
 
diff --git a/tests/system/HTTP/RequestTest.php b/tests/system/HTTP/RequestTest.php
index ab19f05adfac..3eaea59ed1c2 100644
--- a/tests/system/HTTP/RequestTest.php
+++ b/tests/system/HTTP/RequestTest.php
@@ -35,7 +35,7 @@ protected function setUp(): void
         $_GET  = [];
     }
 
-    public function testFetchGlobalsSingleValue()
+    public function testFetchGlobalsSingleValue(): void
     {
         $_POST['foo'] = 'bar';
         $_GET['bar']  = 'baz';
@@ -44,12 +44,12 @@ public function testFetchGlobalsSingleValue()
         $this->assertSame('baz', $this->request->fetchGlobal('get', 'bar'));
     }
 
-    public function testFetchGlobalsReturnsNullWhenNotFound()
+    public function testFetchGlobalsReturnsNullWhenNotFound(): void
     {
         $this->assertNull($this->request->fetchGlobal('post', 'foo'));
     }
 
-    public function testFetchGlobalsFiltersValues()
+    public function testFetchGlobalsFiltersValues(): void
     {
         $this->request->setGlobal('post', [
             'foo' => 'bar<script>',
@@ -60,7 +60,7 @@ public function testFetchGlobalsFiltersValues()
         $this->assertSame('baz', $this->request->fetchGlobal('post', 'bar'));
     }
 
-    public function testFetchGlobalsWithFilterFlag()
+    public function testFetchGlobalsWithFilterFlag(): void
     {
         $this->request->setGlobal('post', [
             'foo' => '`bar<script>',
@@ -71,7 +71,7 @@ public function testFetchGlobalsWithFilterFlag()
         $this->assertSame('baz', $this->request->fetchGlobal('post', 'bar'));
     }
 
-    public function testFetchGlobalReturnsAllWhenEmpty()
+    public function testFetchGlobalReturnsAllWhenEmpty(): void
     {
         $post = [
             'foo' => 'bar',
@@ -84,7 +84,7 @@ public function testFetchGlobalReturnsAllWhenEmpty()
         $this->assertSame($post, $this->request->fetchGlobal('post'));
     }
 
-    public function testFetchGlobalFiltersAllValues()
+    public function testFetchGlobalFiltersAllValues(): void
     {
         $post = [
             'foo' => 'bar<script>',
@@ -103,7 +103,7 @@ public function testFetchGlobalFiltersAllValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', null, FILTER_SANITIZE_ENCODED));
     }
 
-    public function testFetchGlobalFilterWithFlagAllValues()
+    public function testFetchGlobalFilterWithFlagAllValues(): void
     {
         $post = [
             'foo' => '`bar<script>',
@@ -122,7 +122,7 @@ public function testFetchGlobalFilterWithFlagAllValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', null, FILTER_SANITIZE_ENCODED, FILTER_FLAG_STRIP_BACKTICK));
     }
 
-    public function testFetchGlobalReturnsSelectedKeys()
+    public function testFetchGlobalReturnsSelectedKeys(): void
     {
         $post = [
             'foo' => 'bar',
@@ -139,7 +139,7 @@ public function testFetchGlobalReturnsSelectedKeys()
         $this->assertSame($expected, $this->request->fetchGlobal('post', ['foo', 'bar']));
     }
 
-    public function testFetchGlobalFiltersSelectedValues()
+    public function testFetchGlobalFiltersSelectedValues(): void
     {
         $post = [
             'foo' => 'bar<script>',
@@ -156,7 +156,7 @@ public function testFetchGlobalFiltersSelectedValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', ['foo', 'bar'], FILTER_SANITIZE_ENCODED));
     }
 
-    public function testFetchGlobalFilterWithFlagSelectedValues()
+    public function testFetchGlobalFilterWithFlagSelectedValues(): void
     {
         $post = [
             'foo' => '`bar<script>',
@@ -176,7 +176,7 @@ public function testFetchGlobalFilterWithFlagSelectedValues()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/353
      */
-    public function testFetchGlobalReturnsArrayValues()
+    public function testFetchGlobalReturnsArrayValues(): void
     {
         $post = [
             'ANNOUNCEMENTS' => [
@@ -193,7 +193,7 @@ public function testFetchGlobalReturnsArrayValues()
         $this->assertCount(2, $result['ANNOUNCEMENTS']);
     }
 
-    public function testFetchGlobalWithArrayTop()
+    public function testFetchGlobalWithArrayTop(): void
     {
         $post = [
             'clients' => [
@@ -207,7 +207,7 @@ public function testFetchGlobalWithArrayTop()
         $this->assertSame(['address' => ['zipcode' => 90210]], $this->request->fetchGlobal('post', 'clients'));
     }
 
-    public function testFetchGlobalWithArrayChildNumeric()
+    public function testFetchGlobalWithArrayChildNumeric(): void
     {
         $post = [
             'clients' => [
@@ -228,7 +228,7 @@ public function testFetchGlobalWithArrayChildNumeric()
         $this->assertSame(['zipcode' => 60610], $this->request->fetchGlobal('post', 'clients[1][address]'));
     }
 
-    public function testFetchGlobalWithArrayChildElement()
+    public function testFetchGlobalWithArrayChildElement(): void
     {
         $post = [
             'clients' => [
@@ -243,7 +243,7 @@ public function testFetchGlobalWithArrayChildElement()
         $this->assertNull($this->request->fetchGlobal('post', 'clients[zipcode]'));
     }
 
-    public function testFetchGlobalWithKeylessArrayChildElement()
+    public function testFetchGlobalWithKeylessArrayChildElement(): void
     {
         $post = [
             'clients' => [
@@ -258,7 +258,7 @@ public function testFetchGlobalWithKeylessArrayChildElement()
         $this->assertSame([['a']], $this->request->fetchGlobal('post', 'clients[stuff]'));
     }
 
-    public function testFetchGlobalWithArrayLastElement()
+    public function testFetchGlobalWithArrayLastElement(): void
     {
         $post = [
             'clients' => [
@@ -272,7 +272,7 @@ public function testFetchGlobalWithArrayLastElement()
         $this->assertSame('90210', $this->request->fetchGlobal('post', 'clients[address][zipcode]'));
     }
 
-    public function testFetchGlobalWithEmptyNotation()
+    public function testFetchGlobalWithEmptyNotation(): void
     {
         $expected = [
             [
@@ -294,7 +294,7 @@ public function testFetchGlobalWithEmptyNotation()
         $this->assertSame($expected, $this->request->fetchGlobal('post', 'clients[]'));
     }
 
-    public function testFetchGlobalFiltersWithNull()
+    public function testFetchGlobalFiltersWithNull(): void
     {
         $expected = [
             'foo'     => false,
@@ -361,7 +361,7 @@ public function testFetchGlobalFiltersWithNull()
         $this->assertSame($expected, $this->request->fetchGlobal('post', null, FILTER_VALIDATE_INT));
     }
 
-    public function testFetchGlobalFiltersWithValue()
+    public function testFetchGlobalFiltersWithValue(): void
     {
         $expected = [
             [
@@ -420,7 +420,7 @@ public function testFetchGlobalFiltersWithValue()
         $this->assertSame($expected, $this->request->fetchGlobal('post', 'people', FILTER_VALIDATE_INT));
     }
 
-    public function testFetchGlobalFiltersWithValues()
+    public function testFetchGlobalFiltersWithValues(): void
     {
         $expected = [
             'address' => [
@@ -485,7 +485,7 @@ public function testFetchGlobalFiltersWithValues()
         $this->assertSame($expected, $this->request->fetchGlobal('post', ['address', 'people'], FILTER_VALIDATE_INT));
     }
 
-    public function testFetchGlobalFiltersWithArrayChildElement()
+    public function testFetchGlobalFiltersWithArrayChildElement(): void
     {
         $expected = [
             'name' => false,
@@ -585,17 +585,17 @@ public function ipAddressChecks(): iterable
      * @param mixed      $address
      * @param mixed|null $type
      */
-    public function testValidIPAddress($expected, $address, $type = null)
+    public function testValidIPAddress($expected, $address, $type = null): void
     {
         $this->assertSame($expected, $this->request->isValidIP($address, $type));
     }
 
-    public function testGetIPAddressDefault()
+    public function testGetIPAddressDefault(): void
     {
         $this->assertSame('0.0.0.0', $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressNormal()
+    public function testGetIPAddressNormal(): void
     {
         $expected               = '123.123.123.123';
         $_SERVER['REMOTE_ADDR'] = $expected;
@@ -605,7 +605,7 @@ public function testGetIPAddressNormal()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxy()
+    public function testGetIPAddressThruProxy(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['REMOTE_ADDR']          = '10.0.1.200';
@@ -623,7 +623,7 @@ public function testGetIPAddressThruProxy()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyInvalid()
+    public function testGetIPAddressThruProxyInvalid(): void
     {
         $expected                        = '123.456.23.123';
         $_SERVER['REMOTE_ADDR']          = '10.0.1.200';
@@ -641,7 +641,7 @@ public function testGetIPAddressThruProxyInvalid()
         $this->assertSame('10.0.1.200', $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyNotWhitelisted()
+    public function testGetIPAddressThruProxyNotWhitelisted(): void
     {
         $expected                        = '123.456.23.123';
         $_SERVER['REMOTE_ADDR']          = '10.10.1.200';
@@ -659,7 +659,7 @@ public function testGetIPAddressThruProxyNotWhitelisted()
         $this->assertSame('10.10.1.200', $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxySubnet()
+    public function testGetIPAddressThruProxySubnet(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['REMOTE_ADDR']          = '192.168.5.21';
@@ -674,7 +674,7 @@ public function testGetIPAddressThruProxySubnet()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
 
-    public function testGetIPAddressThruProxyOutofSubnet()
+    public function testGetIPAddressThruProxyOutofSubnet(): void
     {
         $expected                        = '123.123.123.123';
         $_SERVER['REMOTE_ADDR']          = '192.168.5.21';
@@ -691,7 +691,7 @@ public function testGetIPAddressThruProxyOutofSubnet()
 
     // FIXME getIPAddress should have more testing, to 100% code coverage
 
-    public function testMethodReturnsRightStuff()
+    public function testMethodReturnsRightStuff(): void
     {
         // Defaults method to GET now.
         $this->assertSame('get', $this->request->getMethod());
diff --git a/tests/system/HTTP/ResponseCookieTest.php b/tests/system/HTTP/ResponseCookieTest.php
index 0c9283f0c88e..bfefa1a3a0bb 100644
--- a/tests/system/HTTP/ResponseCookieTest.php
+++ b/tests/system/HTTP/ResponseCookieTest.php
@@ -39,7 +39,7 @@ protected function tearDown(): void
         Cookie::setDefaults($this->defaults);
     }
 
-    public function testCookiePrefixed()
+    public function testCookiePrefixed(): void
     {
         $config         = config('Cookie');
         $config->prefix = 'mine';
@@ -54,7 +54,7 @@ public function testCookiePrefixed()
         $this->assertFalse($response->hasCookie('foo', null, 'yours'));
     }
 
-    public function testCookiesAll()
+    public function testCookiesAll(): void
     {
         $response = new Response(new App());
         $response->setCookie('foo', 'bar');
@@ -65,7 +65,7 @@ public function testCookiesAll()
         $this->assertTrue($response->hasCookie('bee'));
     }
 
-    public function testSetCookieObject()
+    public function testSetCookieObject(): void
     {
         $cookie   = new Cookie('foo', 'bar');
         $response = new Response(new App());
@@ -76,7 +76,7 @@ public function testSetCookieObject()
         $this->assertTrue($response->hasCookie('foo'));
     }
 
-    public function testCookieGet()
+    public function testCookieGet(): void
     {
         $response = new Response(new App());
         $response->setCookie('foo', 'bar');
@@ -86,7 +86,7 @@ public function testCookieGet()
         $this->assertNull($response->getCookie('bogus'));
     }
 
-    public function testCookieDomain()
+    public function testCookieDomain(): void
     {
         $response = new Response(new App());
 
@@ -106,7 +106,7 @@ public function testCookieDomain()
         $this->assertSame('mine.com', $cookie->getDomain());
     }
 
-    public function testCookiePath()
+    public function testCookiePath(): void
     {
         $response = new Response(new App());
 
@@ -119,7 +119,7 @@ public function testCookiePath()
         $this->assertSame('/tmp/here', $cookie->getPath());
     }
 
-    public function testCookieSecure()
+    public function testCookieSecure(): void
     {
         $response = new Response(new App());
 
@@ -132,7 +132,7 @@ public function testCookieSecure()
         $this->assertTrue($cookie->isSecure());
     }
 
-    public function testCookieHTTPOnly()
+    public function testCookieHTTPOnly(): void
     {
         $response = new Response(new App());
 
@@ -145,7 +145,7 @@ public function testCookieHTTPOnly()
         $this->assertFalse($cookie->isHTTPOnly());
     }
 
-    public function testCookieExpiry()
+    public function testCookieExpiry(): void
     {
         $response = new Response(new App());
 
@@ -164,7 +164,7 @@ public function testCookieExpiry()
         $this->assertSame(0, $cookie->getExpiresTimestamp());
     }
 
-    public function testCookieDelete()
+    public function testCookieDelete(): void
     {
         $response = new Response(new App());
 
@@ -226,7 +226,7 @@ public function testCookieDelete()
         $this->assertSame($cookie->getExpiresTimestamp(), 0);
     }
 
-    public function testCookieDefaultSetSameSite()
+    public function testCookieDefaultSetSameSite(): void
     {
         $response = new Response(new App());
         $response->setCookie([
@@ -240,7 +240,7 @@ public function testCookieDefaultSetSameSite()
         $this->assertSame('Lax', $allCookies['bar;/;']->getSameSite());
     }
 
-    public function testCookieStrictSetSameSite()
+    public function testCookieStrictSetSameSite(): void
     {
         $config           = config('Cookie');
         $config->samesite = 'Strict';
@@ -256,7 +256,7 @@ public function testCookieStrictSetSameSite()
         $this->assertSame('Strict', $allCookies['bar;/;']->getSameSite());
     }
 
-    public function testCookieBlankSetSameSite()
+    public function testCookieBlankSetSameSite(): void
     {
         /** @var CookieConfig $config */
         $config           = config('Cookie');
@@ -273,7 +273,7 @@ public function testCookieBlankSetSameSite()
         $this->assertSame('', $allCookies['bar;/;']->getSameSite());
     }
 
-    public function testCookieWithoutSameSite()
+    public function testCookieWithoutSameSite(): void
     {
         $config = new CookieConfig();
         unset($config->samesite);
@@ -289,7 +289,7 @@ public function testCookieWithoutSameSite()
         $this->assertSame('Lax', $allCookies['bar;/;']->getSameSite());
     }
 
-    public function testCookieStrictSameSite()
+    public function testCookieStrictSameSite(): void
     {
         $response = new Response(new App());
         $response->setCookie([
@@ -304,7 +304,7 @@ public function testCookieStrictSameSite()
         $this->assertSame('Strict', $allCookies['bar;/;']->getSameSite());
     }
 
-    public function testCookieInvalidSameSite()
+    public function testCookieInvalidSameSite(): void
     {
         $response = new Response(new App());
 
@@ -318,7 +318,7 @@ public function testCookieInvalidSameSite()
         ]);
     }
 
-    public function testSetCookieConfigCookieIsUsed()
+    public function testSetCookieConfigCookieIsUsed(): void
     {
         /** @var CookieConfig $config */
         $config           = config('Cookie');
@@ -342,7 +342,7 @@ public function testSetCookieConfigCookieIsUsed()
         $this->assertSame('None', $options['samesite']);
     }
 
-    public function testGetCookieStore()
+    public function testGetCookieStore(): void
     {
         $response = new Response(new App());
         $this->assertInstanceOf(CookieStore::class, $response->getCookieStore());
diff --git a/tests/system/HTTP/ResponseSendTest.php b/tests/system/HTTP/ResponseSendTest.php
index d482582e2207..437d379fdf9d 100644
--- a/tests/system/HTTP/ResponseSendTest.php
+++ b/tests/system/HTTP/ResponseSendTest.php
@@ -46,7 +46,7 @@ final class ResponseSendTest extends CIUnitTestCase
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeadersMissingDate()
+    public function testHeadersMissingDate(): void
     {
         $response = new Response(new App());
         $response->pretend(false);
@@ -79,7 +79,7 @@ public function testHeadersMissingDate()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeadersWithCSP()
+    public function testHeadersWithCSP(): void
     {
         $this->resetFactories();
         $this->resetServices();
@@ -115,7 +115,7 @@ public function testHeadersWithCSP()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testRedirectResponseCookies()
+    public function testRedirectResponseCookies(): void
     {
         $loginTime = time();
 
diff --git a/tests/system/HTTP/ResponseTest.php b/tests/system/HTTP/ResponseTest.php
index ce320417748c..c9cb68807ac4 100644
--- a/tests/system/HTTP/ResponseTest.php
+++ b/tests/system/HTTP/ResponseTest.php
@@ -46,7 +46,7 @@ protected function tearDown(): void
         $_SERVER = $this->server;
     }
 
-    public function testCanSetStatusCode()
+    public function testCanSetStatusCode(): void
     {
         $response = new Response(new App());
 
@@ -55,7 +55,7 @@ public function testCanSetStatusCode()
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testSetStatusCodeThrowsExceptionForBadCodes()
+    public function testSetStatusCodeThrowsExceptionForBadCodes(): void
     {
         $response = new Response(new App());
 
@@ -63,7 +63,7 @@ public function testSetStatusCodeThrowsExceptionForBadCodes()
         $response->setStatusCode(54322);
     }
 
-    public function testConstructWithCSPEnabled()
+    public function testConstructWithCSPEnabled(): void
     {
         $config             = new App();
         $config->CSPEnabled = true;
@@ -72,7 +72,7 @@ public function testConstructWithCSPEnabled()
         $this->assertInstanceOf(Response::class, $response);
     }
 
-    public function testSetStatusCodeSetsReason()
+    public function testSetStatusCodeSetsReason(): void
     {
         $response = new Response(new App());
 
@@ -81,7 +81,7 @@ public function testSetStatusCodeSetsReason()
         $this->assertSame('OK', $response->getReasonPhrase());
     }
 
-    public function testCanSetCustomReasonCode()
+    public function testCanSetCustomReasonCode(): void
     {
         $response = new Response(new App());
 
@@ -90,7 +90,7 @@ public function testCanSetCustomReasonCode()
         $this->assertSame('Not the mama', $response->getReasonPhrase());
     }
 
-    public function testRequiresMessageWithUnknownStatusCode()
+    public function testRequiresMessageWithUnknownStatusCode(): void
     {
         $response = new Response(new App());
 
@@ -99,7 +99,7 @@ public function testRequiresMessageWithUnknownStatusCode()
         $response->setStatusCode(115);
     }
 
-    public function testRequiresMessageWithSmallStatusCode()
+    public function testRequiresMessageWithSmallStatusCode(): void
     {
         $response = new Response(new App());
 
@@ -108,7 +108,7 @@ public function testRequiresMessageWithSmallStatusCode()
         $response->setStatusCode(95);
     }
 
-    public function testRequiresMessageWithLargeStatusCode()
+    public function testRequiresMessageWithLargeStatusCode(): void
     {
         $response = new Response(new App());
 
@@ -117,7 +117,7 @@ public function testRequiresMessageWithLargeStatusCode()
         $response->setStatusCode(695);
     }
 
-    public function testSetStatusCodeInterpretsReason()
+    public function testSetStatusCodeInterpretsReason(): void
     {
         $response = new Response(new App());
 
@@ -126,7 +126,7 @@ public function testSetStatusCodeInterpretsReason()
         $this->assertSame('Multiple Choices', $response->getReasonPhrase());
     }
 
-    public function testSetStatusCodeSavesCustomReason()
+    public function testSetStatusCodeSavesCustomReason(): void
     {
         $response = new Response(new App());
 
@@ -135,14 +135,14 @@ public function testSetStatusCodeSavesCustomReason()
         $this->assertSame('My Little Pony', $response->getReasonPhrase());
     }
 
-    public function testGetReasonDefaultsToOK()
+    public function testGetReasonDefaultsToOK(): void
     {
         $response = new Response(new App());
 
         $this->assertSame('OK', $response->getReasonPhrase());
     }
 
-    public function testSetDateRemembersDateInUTC()
+    public function testSetDateRemembersDateInUTC(): void
     {
         $response = new Response(new App());
 
@@ -157,7 +157,7 @@ public function testSetDateRemembersDateInUTC()
         $this->assertSame($date->format('D, d M Y H:i:s') . ' GMT', $header);
     }
 
-    public function testSetLink()
+    public function testSetLink(): void
     {
         // Ensure our URL is not getting overridden
         $config          = new App();
@@ -194,7 +194,7 @@ public function testSetLink()
         );
     }
 
-    public function testSetContentType()
+    public function testSetContentType(): void
     {
         $response = new Response(new App());
 
@@ -203,7 +203,7 @@ public function testSetContentType()
         $this->assertSame('text/json; charset=UTF-8', $response->getHeaderLine('Content-Type'));
     }
 
-    public function testNoCache()
+    public function testNoCache(): void
     {
         $response = new Response(new App());
 
@@ -212,7 +212,7 @@ public function testNoCache()
         $this->assertSame('no-store, max-age=0, no-cache', $response->getHeaderLine('Cache-control'));
     }
 
-    public function testSetCache()
+    public function testSetCache(): void
     {
         $response = new Response(new App());
 
@@ -232,7 +232,7 @@ public function testSetCache()
         $this->assertSame('max-age=300, must-revalidate', $response->getHeaderLine('Cache-Control'));
     }
 
-    public function testSetCacheNoOptions()
+    public function testSetCacheNoOptions(): void
     {
         $response = new Response(new App());
 
@@ -243,7 +243,7 @@ public function testSetCacheNoOptions()
         $this->assertSame('no-store, max-age=0, no-cache', $response->getHeaderLine('Cache-Control'));
     }
 
-    public function testSetLastModifiedWithDateTimeObject()
+    public function testSetLastModifiedWithDateTimeObject(): void
     {
         $response = new Response(new App());
 
@@ -258,7 +258,7 @@ public function testSetLastModifiedWithDateTimeObject()
         $this->assertSame($date->format('D, d M Y H:i:s') . ' GMT', $header);
     }
 
-    public function testRedirectSetsDefaultCodeAndLocationHeader()
+    public function testRedirectSetsDefaultCodeAndLocationHeader(): void
     {
         $response = new Response(new App());
 
@@ -278,7 +278,7 @@ public function testRedirect(
         string $method,
         ?int $code,
         int $expectedCode
-    ) {
+    ): void {
         $_SERVER['SERVER_SOFTWARE'] = $server;
         $_SERVER['SERVER_PROTOCOL'] = $protocol;
         $_SERVER['REQUEST_METHOD']  = $method;
@@ -323,7 +323,7 @@ public function testRedirectWithIIS(
         string $method,
         ?int $code,
         int $expectedCode
-    ) {
+    ): void {
         $_SERVER['SERVER_SOFTWARE'] = 'Microsoft-IIS';
         $_SERVER['SERVER_PROTOCOL'] = 'HTTP/1.1';
         $_SERVER['REQUEST_METHOD']  = 'POST';
@@ -349,14 +349,14 @@ public function provideForRedirectWithIIS(): iterable
         ];
     }
 
-    public function testSetCookieFails()
+    public function testSetCookieFails(): void
     {
         $response = new Response(new App());
 
         $this->assertFalse($response->hasCookie('foo'));
     }
 
-    public function testSetCookieMatch()
+    public function testSetCookieMatch(): void
     {
         $response = new Response(new App());
         $response->setCookie('foo', 'bar');
@@ -365,7 +365,7 @@ public function testSetCookieMatch()
         $this->assertTrue($response->hasCookie('foo', 'bar'));
     }
 
-    public function testSetCookieFailDifferentPrefix()
+    public function testSetCookieFailDifferentPrefix(): void
     {
         $response = new Response(new App());
         $response->setCookie('foo', 'bar', '', '', '', 'ack');
@@ -373,7 +373,7 @@ public function testSetCookieFailDifferentPrefix()
         $this->assertFalse($response->hasCookie('foo'));
     }
 
-    public function testSetCookieSuccessOnPrefix()
+    public function testSetCookieSuccessOnPrefix(): void
     {
         $response = new Response(new App());
         $response->setCookie('foo', 'bar', '', '', '', 'ack');
@@ -382,7 +382,7 @@ public function testSetCookieSuccessOnPrefix()
         $this->assertFalse($response->hasCookie('foo', null, 'nak'));
     }
 
-    public function testJSONWithArray()
+    public function testJSONWithArray(): void
     {
         $body = [
             'foo' => 'bar',
@@ -401,7 +401,7 @@ public function testJSONWithArray()
         $this->assertStringContainsString('application/json', $response->getHeaderLine('content-type'));
     }
 
-    public function testJSONGetFromNormalBody()
+    public function testJSONGetFromNormalBody(): void
     {
         $body = [
             'foo' => 'bar',
@@ -419,7 +419,7 @@ public function testJSONGetFromNormalBody()
         $this->assertSame($expected, $response->getJSON());
     }
 
-    public function testXMLWithArray()
+    public function testXMLWithArray(): void
     {
         $body = [
             'foo' => 'bar',
@@ -438,7 +438,7 @@ public function testXMLWithArray()
         $this->assertStringContainsString('application/xml', $response->getHeaderLine('content-type'));
     }
 
-    public function testXMLGetFromNormalBody()
+    public function testXMLGetFromNormalBody(): void
     {
         $body = [
             'foo' => 'bar',
@@ -456,7 +456,7 @@ public function testXMLGetFromNormalBody()
         $this->assertSame($expected, $response->getXML());
     }
 
-    public function testGetDownloadResponseByData()
+    public function testGetDownloadResponseByData(): void
     {
         $response = new Response(new App());
 
@@ -474,7 +474,7 @@ public function testGetDownloadResponseByData()
         $this->assertSame('data', $actualOutput);
     }
 
-    public function testGetDownloadResponseByFilePath()
+    public function testGetDownloadResponseByFilePath(): void
     {
         $response = new Response(new App());
 
@@ -492,7 +492,7 @@ public function testGetDownloadResponseByFilePath()
         $this->assertSame(file_get_contents(__FILE__), $actualOutput);
     }
 
-    public function testVagueDownload()
+    public function testVagueDownload(): void
     {
         $response = new Response(new App());
 
@@ -501,7 +501,7 @@ public function testVagueDownload()
         $this->assertNull($actual);
     }
 
-    public function testPretendMode()
+    public function testPretendMode(): void
     {
         $response = new MockResponse(new App());
         $response->pretend(true);
@@ -510,7 +510,7 @@ public function testPretendMode()
         $this->assertFalse($response->getPretend());
     }
 
-    public function testMisbehaving()
+    public function testMisbehaving(): void
     {
         $response = new MockResponse(new App());
         $response->misbehave();
@@ -519,7 +519,7 @@ public function testMisbehaving()
         $response->getStatusCode();
     }
 
-    public function testTemporaryRedirectHTTP11()
+    public function testTemporaryRedirectHTTP11(): void
     {
         $_SERVER['SERVER_PROTOCOL'] = 'HTTP/1.1';
         $_SERVER['REQUEST_METHOD']  = 'POST';
@@ -531,7 +531,7 @@ public function testTemporaryRedirectHTTP11()
         $this->assertSame(303, $response->getStatusCode());
     }
 
-    public function testTemporaryRedirectGetHTTP11()
+    public function testTemporaryRedirectGetHTTP11(): void
     {
         $_SERVER['SERVER_PROTOCOL'] = 'HTTP/1.1';
         $_SERVER['REQUEST_METHOD']  = 'GET';
@@ -545,7 +545,7 @@ public function testTemporaryRedirectGetHTTP11()
 
     // Make sure cookies are set by RedirectResponse this way
     // See https://github.com/codeigniter4/CodeIgniter4/issues/1393
-    public function testRedirectResponseCookies()
+    public function testRedirectResponseCookies(): void
     {
         $loginTime = time();
 
@@ -559,7 +559,7 @@ public function testRedirectResponseCookies()
     }
 
     // Make sure we don't blow up if pretending to send headers
-    public function testPretendOutput()
+    public function testPretendOutput(): void
     {
         $response = new Response(new App());
         $response->pretend(true);
@@ -574,7 +574,7 @@ public function testPretendOutput()
         $this->assertSame('Happy days', $actual);
     }
 
-    public function testInvalidSameSiteCookie()
+    public function testInvalidSameSiteCookie(): void
     {
         $config                 = new App();
         $config->cookieSameSite = 'Invalid';
diff --git a/tests/system/HTTP/URITest.php b/tests/system/HTTP/URITest.php
index c65a363ac21e..dd802ec5de55 100644
--- a/tests/system/HTTP/URITest.php
+++ b/tests/system/HTTP/URITest.php
@@ -26,7 +26,7 @@
  */
 final class URITest extends CIUnitTestCase
 {
-    public function testConstructorSetsAllParts()
+    public function testConstructorSetsAllParts(): void
     {
         $uri = new URI('http://username:password@hostname:9090/path?arg=value#anchor');
 
@@ -44,7 +44,7 @@ public function testConstructorSetsAllParts()
         $this->assertSame(['path'], $uri->getSegments());
     }
 
-    public function testSegmentsIsPopulatedRightForMultipleSegments()
+    public function testSegmentsIsPopulatedRightForMultipleSegments(): void
     {
         $uri = new URI('http://hostname/path/to/script');
 
@@ -57,7 +57,7 @@ public function testSegmentsIsPopulatedRightForMultipleSegments()
         $this->assertSame(3, $uri->getTotalSegments());
     }
 
-    public function testSegmentOutOfRange()
+    public function testSegmentOutOfRange(): void
     {
         $this->expectException(HTTPException::class);
 
@@ -65,7 +65,7 @@ public function testSegmentOutOfRange()
         $uri->getSegment(5);
     }
 
-    public function testSegmentOutOfRangeWithSilent()
+    public function testSegmentOutOfRangeWithSilent(): void
     {
         $url = 'http://abc.com/a123/b/c';
         $uri = new URI($url);
@@ -73,7 +73,7 @@ public function testSegmentOutOfRangeWithSilent()
         $this->assertSame('', $uri->setSilent()->getSegment(22));
     }
 
-    public function testSegmentOutOfRangeWithDefaultValue()
+    public function testSegmentOutOfRangeWithDefaultValue(): void
     {
         $this->expectException(HTTPException::class);
 
@@ -82,7 +82,7 @@ public function testSegmentOutOfRangeWithDefaultValue()
         $uri->getSegment(22, 'something');
     }
 
-    public function testSegmentOutOfRangeWithSilentAndDefaultValue()
+    public function testSegmentOutOfRangeWithSilentAndDefaultValue(): void
     {
         $url = 'http://abc.com/a123/b/c';
         $uri = new URI($url);
@@ -90,7 +90,7 @@ public function testSegmentOutOfRangeWithSilentAndDefaultValue()
         $this->assertSame('something', $uri->setSilent()->getSegment(22, 'something'));
     }
 
-    public function testSegmentsWithDefaultValueAndSilent()
+    public function testSegmentsWithDefaultValueAndSilent(): void
     {
         $uri = new URI('http://hostname/path/to');
         $uri->setSilent();
@@ -104,7 +104,7 @@ public function testSegmentsWithDefaultValueAndSilent()
         $this->assertSame(2, $uri->getTotalSegments());
     }
 
-    public function testSegmentOutOfRangeWithDefaultValuesAndSilent()
+    public function testSegmentOutOfRangeWithDefaultValuesAndSilent(): void
     {
         $uri = new URI('http://hostname/path/to/script');
         $uri->setSilent();
@@ -116,7 +116,7 @@ public function testSegmentOutOfRangeWithDefaultValuesAndSilent()
         $this->assertSame(['path', 'to', 'script'], $uri->getSegments());
     }
 
-    public function testCanCastAsString()
+    public function testCanCastAsString(): void
     {
         $url = 'http://username:password@hostname:9090/path?arg=value#anchor';
         $uri = new URI($url);
@@ -128,7 +128,7 @@ public function testCanCastAsString()
     /**
      * @dataProvider provideURLs
      */
-    public function testSimpleUri(string $url, string $expectedURL, string $expectedPath)
+    public function testSimpleUri(string $url, string $expectedURL, string $expectedPath): void
     {
         $uri = new URI($url);
 
@@ -187,7 +187,7 @@ public function provideURLs(): iterable
         ];
     }
 
-    public function testEmptyUri()
+    public function testEmptyUri(): void
     {
         $url = '';
         $uri = new URI($url);
@@ -200,7 +200,7 @@ public function testEmptyUri()
         $this->assertSame('http://', (string) $uri);
     }
 
-    public function testMalformedUri()
+    public function testMalformedUri(): void
     {
         $this->expectException(HTTPException::class);
 
@@ -208,7 +208,7 @@ public function testMalformedUri()
         new URI($url);
     }
 
-    public function testMissingScheme()
+    public function testMissingScheme(): void
     {
         $url = 'http://foo.bar/baz';
         $uri = new URI($url);
@@ -219,7 +219,7 @@ public function testMissingScheme()
         $this->assertSame($url, (string) $uri);
     }
 
-    public function testSchemeSub()
+    public function testSchemeSub(): void
     {
         $url = 'example.com';
         $uri = new URI('http://' . $url);
@@ -228,7 +228,7 @@ public function testSchemeSub()
         $this->assertSame('x://' . $url, (string) $uri);
     }
 
-    public function testSetSchemeSetsValue()
+    public function testSetSchemeSetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -240,7 +240,7 @@ public function testSetSchemeSetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetUserInfoSetsValue()
+    public function testSetUserInfoSetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -252,7 +252,7 @@ public function testSetUserInfoSetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testUserInfoCanShowPassword()
+    public function testUserInfoCanShowPassword(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -270,7 +270,7 @@ public function testUserInfoCanShowPassword()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetHostSetsValue()
+    public function testSetHostSetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -282,7 +282,7 @@ public function testSetHostSetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetPortSetsValue()
+    public function testSetPortSetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -294,7 +294,7 @@ public function testSetPortSetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetPortInvalidValues()
+    public function testSetPortInvalidValues(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -308,7 +308,7 @@ public function testSetPortInvalidValues()
         $uri->setPort(70000);
     }
 
-    public function testSetPortInvalidValuesSilent()
+    public function testSetPortInvalidValuesSilent(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -318,7 +318,7 @@ public function testSetPortInvalidValuesSilent()
         $this->assertNull($uri->getPort());
     }
 
-    public function testSetPortTooSmall()
+    public function testSetPortTooSmall(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -329,7 +329,7 @@ public function testSetPortTooSmall()
         $uri->setPort(-1);
     }
 
-    public function testSetPortZero()
+    public function testSetPortZero(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -340,7 +340,7 @@ public function testSetPortZero()
         $uri->setPort(0);
     }
 
-    public function testCatchesBadPort()
+    public function testCatchesBadPort(): void
     {
         $this->expectException(HTTPException::class);
 
@@ -349,7 +349,7 @@ public function testCatchesBadPort()
         $uri->setURI($url);
     }
 
-    public function testSetPathSetsValue()
+    public function testSetPathSetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -364,7 +364,7 @@ public function testSetPathSetsValue()
     /**
      * @dataProvider providePaths
      */
-    public function testSetPath(string $path, string $expectedURL, string $expectedPath)
+    public function testSetPath(string $path, string $expectedURL, string $expectedPath): void
     {
         $url = 'http://example.com/';
         $uri = new URI($url);
@@ -467,7 +467,7 @@ public function invalidPaths(): iterable
      * @param string $path
      * @param string $expected
      */
-    public function testPathGetsFiltered($path, $expected)
+    public function testPathGetsFiltered($path, $expected): void
     {
         $uri = new URI();
         $uri->setPath($path);
@@ -475,7 +475,7 @@ public function testPathGetsFiltered($path, $expected)
         $this->assertSame($expected, $uri->getPath());
     }
 
-    public function testSetFragmentSetsValue()
+    public function testSetFragmentSetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -487,7 +487,7 @@ public function testSetFragmentSetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetQuerySetsValue()
+    public function testSetQuerySetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -499,7 +499,7 @@ public function testSetQuerySetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetQuerySetsValueWithUseRawQueryString()
+    public function testSetQuerySetsValueWithUseRawQueryString(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -511,7 +511,7 @@ public function testSetQuerySetsValueWithUseRawQueryString()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetQueryArraySetsValue()
+    public function testSetQueryArraySetsValue(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -523,7 +523,7 @@ public function testSetQueryArraySetsValue()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetQueryArraySetsValueWithUseRawQueryString()
+    public function testSetQueryArraySetsValueWithUseRawQueryString(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -535,7 +535,7 @@ public function testSetQueryArraySetsValueWithUseRawQueryString()
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetQueryThrowsErrorWhenFragmentPresent()
+    public function testSetQueryThrowsErrorWhenFragmentPresent(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -545,7 +545,7 @@ public function testSetQueryThrowsErrorWhenFragmentPresent()
         $uri->setQuery('?key=value#fragment');
     }
 
-    public function testSetQueryThrowsErrorWhenFragmentPresentSilent()
+    public function testSetQueryThrowsErrorWhenFragmentPresentSilent(): void
     {
         $url = 'http://example.com/path';
         $uri = new URI($url);
@@ -583,7 +583,7 @@ public function authorityInfo(): iterable
      * @param string $url
      * @param string $expected
      */
-    public function testAuthorityReturnsExceptedValues($url, $expected)
+    public function testAuthorityReturnsExceptedValues($url, $expected): void
     {
         $uri = new URI($url);
 
@@ -610,7 +610,7 @@ public function defaultPorts(): iterable
      * @param string $scheme
      * @param int    $port
      */
-    public function testAuthorityRemovesDefaultPorts($scheme, $port)
+    public function testAuthorityRemovesDefaultPorts($scheme, $port): void
     {
         $url = "{$scheme}://example.com:{$port}/path";
         $uri = new URI($url);
@@ -619,7 +619,7 @@ public function testAuthorityRemovesDefaultPorts($scheme, $port)
         $this->assertSame($expected, (string) $uri);
     }
 
-    public function testSetAuthorityReconstitutes()
+    public function testSetAuthorityReconstitutes(): void
     {
         $authority = 'me@foo.com:3000';
 
@@ -733,7 +733,7 @@ public function defaultDots(): iterable
      * @param string $path
      * @param string $expected
      */
-    public function testRemoveDotSegments($path, $expected)
+    public function testRemoveDotSegments($path, $expected): void
     {
         $this->assertSame($expected, URI::removeDotSegments($path));
     }
@@ -774,7 +774,7 @@ public function defaultResolutions(): iterable
      * @param string $rel
      * @param string $expected
      */
-    public function testResolveRelativeURI($rel, $expected)
+    public function testResolveRelativeURI($rel, $expected): void
     {
         $base = 'http://a/b/c/d';
         $uri  = new URI($base);
@@ -790,7 +790,7 @@ public function testResolveRelativeURI($rel, $expected)
      * @param string $rel
      * @param string $expected
      */
-    public function testResolveRelativeURIHTTPS($rel, $expected)
+    public function testResolveRelativeURIHTTPS($rel, $expected): void
     {
         $base     = 'https://a/b/c/d';
         $expected = str_replace('http:', 'https:', $expected);
@@ -802,7 +802,7 @@ public function testResolveRelativeURIHTTPS($rel, $expected)
         $this->assertSame($expected, (string) $new);
     }
 
-    public function testResolveRelativeURIWithNoBase()
+    public function testResolveRelativeURIWithNoBase(): void
     {
         $base = 'http://a';
         $uri  = new URI($base);
@@ -812,7 +812,7 @@ public function testResolveRelativeURIWithNoBase()
         $this->assertSame('http://a/x', (string) $new);
     }
 
-    public function testAddQueryVar()
+    public function testAddQueryVar(): void
     {
         $base = 'http://example.com/foo';
         $uri  = new URI($base);
@@ -825,7 +825,7 @@ public function testAddQueryVar()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/pull/954
      */
-    public function testSetQueryDecode()
+    public function testSetQueryDecode(): void
     {
         $base    = 'http://example.com/foo';
         $uri     = new URI($base);
@@ -838,7 +838,7 @@ public function testSetQueryDecode()
         $this->assertSame("q={$encoded}", $uri->getQuery());
     }
 
-    public function testAddQueryVarRespectsExistingQueryVars()
+    public function testAddQueryVarRespectsExistingQueryVars(): void
     {
         $base = 'http://example.com/foo?bar=baz';
         $uri  = new URI($base);
@@ -848,7 +848,7 @@ public function testAddQueryVarRespectsExistingQueryVars()
         $this->assertSame('http://example.com/foo?bar=baz&baz=foz', (string) $uri);
     }
 
-    public function testStripQueryVars()
+    public function testStripQueryVars(): void
     {
         $base = 'http://example.com/foo?foo=bar&bar=baz&baz=foz';
         $uri  = new URI($base);
@@ -858,7 +858,7 @@ public function testStripQueryVars()
         $this->assertSame('http://example.com/foo?foo=bar', (string) $uri);
     }
 
-    public function testKeepQueryVars()
+    public function testKeepQueryVars(): void
     {
         $base = 'http://example.com/foo?foo=bar&bar=baz&baz=foz';
         $uri  = new URI($base);
@@ -868,7 +868,7 @@ public function testKeepQueryVars()
         $this->assertSame('http://example.com/foo?bar=baz&baz=foz', (string) $uri);
     }
 
-    public function testEmptyQueryVars()
+    public function testEmptyQueryVars(): void
     {
         $base = 'http://example.com/foo';
         $uri  = new URI($base);
@@ -878,7 +878,7 @@ public function testEmptyQueryVars()
         $this->assertSame('http://example.com/foo?foo=&bar=baz&baz=foz', (string) $uri);
     }
 
-    public function testGetQueryExcept()
+    public function testGetQueryExcept(): void
     {
         $base = 'http://example.com/foo?foo=bar&bar=baz&baz=foz';
         $uri  = new URI($base);
@@ -886,7 +886,7 @@ public function testGetQueryExcept()
         $this->assertSame('foo=bar&baz=foz', $uri->getQuery(['except' => ['bar']]));
     }
 
-    public function testGetQueryOnly()
+    public function testGetQueryOnly(): void
     {
         $base = 'http://example.com/foo?foo=bar&bar=baz&baz=foz';
         $uri  = new URI($base);
@@ -895,7 +895,7 @@ public function testGetQueryOnly()
         $this->assertSame('foo=bar&baz=foz', $uri->getQuery(['except' => 'bar']));
     }
 
-    public function testGetQueryWithStrings()
+    public function testGetQueryWithStrings(): void
     {
         $base = 'http://example.com/foo?foo=bar&bar=baz&baz=foz';
         $uri  = new URI($base);
@@ -906,7 +906,7 @@ public function testGetQueryWithStrings()
     /**
      * @see   https://github.com/codeigniter4/CodeIgniter4/issues/331
      */
-    public function testNoExtraSlashes()
+    public function testNoExtraSlashes(): void
     {
         $this->assertSame(
             'http://entirely.different.com/subfolder',
@@ -922,7 +922,7 @@ public function testNoExtraSlashes()
         );
     }
 
-    public function testSetSegment()
+    public function testSetSegment(): void
     {
         $base = 'http://example.com/foo/bar/baz';
         $uri  = new URI($base);
@@ -932,7 +932,7 @@ public function testSetSegment()
         $this->assertSame('foo/banana/baz', $uri->getPath());
     }
 
-    public function testSetSegmentFallback()
+    public function testSetSegmentFallback(): void
     {
         $base = 'http://example.com';
 
@@ -960,7 +960,7 @@ public function testSetSegmentFallback()
         $uri->setSegment(8, 'eighth');
     }
 
-    public function testSetBadSegment()
+    public function testSetBadSegment(): void
     {
         $this->expectException(HTTPException::class);
 
@@ -970,7 +970,7 @@ public function testSetBadSegment()
         $uri->setSegment(6, 'banana');
     }
 
-    public function testSetBadSegmentSilent()
+    public function testSetBadSegmentSilent(): void
     {
         $base     = 'http://example.com/foo/bar/baz';
         $uri      = new URI($base);
@@ -983,7 +983,7 @@ public function testSetBadSegmentSilent()
 
     // Exploratory testing, investigating https://github.com/codeigniter4/CodeIgniter4/issues/2016
 
-    public function testBasedNoIndex()
+    public function testBasedNoIndex(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/ci/v4/controller/method';
@@ -1013,7 +1013,7 @@ public function testBasedNoIndex()
         $this->assertSame($uri->getPath(), '/' . $request->getUri()->getPath());
     }
 
-    public function testBasedWithIndex()
+    public function testBasedWithIndex(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/ci/v4/index.php/controller/method';
@@ -1049,7 +1049,7 @@ public function testBasedWithIndex()
         $this->assertSame($uri->getPath(), '/' . $request->getUri()->getPath());
     }
 
-    public function testForceGlobalSecureRequests()
+    public function testForceGlobalSecureRequests(): void
     {
         $this->resetServices();
 
@@ -1084,7 +1084,7 @@ public function testForceGlobalSecureRequests()
         );
     }
 
-    public function testZeroAsURIPath()
+    public function testZeroAsURIPath(): void
     {
         $url = 'http://example.com/0';
         $uri = new URI($url);
@@ -1093,7 +1093,7 @@ public function testZeroAsURIPath()
         $this->assertSame('/0', $uri->getPath());
     }
 
-    public function testEmptyURIPath()
+    public function testEmptyURIPath(): void
     {
         $url = 'http://example.com/';
         $uri = new URI($url);
@@ -1103,7 +1103,7 @@ public function testEmptyURIPath()
         $this->assertSame(0, $uri->getTotalSegments());
     }
 
-    public function testSetURI()
+    public function testSetURI(): void
     {
         $url = ':';
         $uri = new URI();
@@ -1114,7 +1114,7 @@ public function testSetURI()
         $uri->setURI($url);
     }
 
-    public function testSetURISilent()
+    public function testSetURISilent(): void
     {
         $url = ':';
         $uri = new URI();
@@ -1124,7 +1124,7 @@ public function testSetURISilent()
         $this->assertTrue(true);
     }
 
-    public function testCreateURIStringNoArguments()
+    public function testCreateURIStringNoArguments(): void
     {
         $uri = URI::createURIString();
 
@@ -1132,7 +1132,7 @@ public function testCreateURIStringNoArguments()
         $this->assertSame($expected, $uri);
     }
 
-    public function testCreateURIStringOnlyAuthority()
+    public function testCreateURIStringOnlyAuthority(): void
     {
         $uri = URI::createURIString(null, 'example.com');
 
@@ -1140,7 +1140,7 @@ public function testCreateURIStringOnlyAuthority()
         $this->assertSame($expected, $uri);
     }
 
-    public function testCreateURIString()
+    public function testCreateURIString(): void
     {
         $uri = URI::createURIString('https', 'example.com', '/');
 
@@ -1148,7 +1148,7 @@ public function testCreateURIString()
         $this->assertSame($expected, $uri);
     }
 
-    public function testCreateURIStringAuthorityMisuseEndWithSlash()
+    public function testCreateURIStringAuthorityMisuseEndWithSlash(): void
     {
         $uri = URI::createURIString('https', 'example.com/', '/');
 
@@ -1159,7 +1159,7 @@ public function testCreateURIStringAuthorityMisuseEndWithSlash()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5728
      */
-    public function testForceGlobalSecureRequestsAndNonHTTPProtocol()
+    public function testForceGlobalSecureRequestsAndNonHTTPProtocol(): void
     {
         $config                            = new App();
         $config->forceGlobalSecureRequests = true;
diff --git a/tests/system/HTTP/UserAgentTest.php b/tests/system/HTTP/UserAgentTest.php
index 4c5898c204fd..abe72075130e 100644
--- a/tests/system/HTTP/UserAgentTest.php
+++ b/tests/system/HTTP/UserAgentTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
         $this->agent = new UserAgent();
     }
 
-    public function testMobile()
+    public function testMobile(): void
     {
         // Mobile Not Set
         $_SERVER['HTTP_USER_AGENT'] = $this->_mobile_ua;
@@ -42,7 +42,7 @@ public function testMobile()
         unset($_SERVER['HTTP_USER_AGENT']);
     }
 
-    public function testIsFunctions()
+    public function testIsFunctions(): void
     {
         $this->assertTrue($this->agent->isBrowser());
         $this->assertTrue($this->agent->isBrowser('Safari'));
@@ -51,7 +51,7 @@ public function testIsFunctions()
         $this->assertFalse($this->agent->isMobile());
     }
 
-    public function testReferrer()
+    public function testReferrer(): void
     {
         $_SERVER['HTTP_REFERER'] = 'http://codeigniter.com/user_guide/';
         $this->assertTrue($this->agent->isReferral());
@@ -63,12 +63,12 @@ public function testReferrer()
         $this->assertSame('', $this->agent->getReferrer());
     }
 
-    public function testAgentString()
+    public function testAgentString(): void
     {
         $this->assertSame($this->_user_agent, $this->agent->getAgentString());
     }
 
-    public function testBrowserInfo()
+    public function testBrowserInfo(): void
     {
         $this->assertSame('Mac OS X', $this->agent->getPlatform());
         $this->assertSame('Safari', $this->agent->getBrowser());
@@ -76,7 +76,7 @@ public function testBrowserInfo()
         $this->assertSame('', $this->agent->getRobot());
     }
 
-    public function testParse()
+    public function testParse(): void
     {
         $newAgent = 'Mozilla/5.0 (Android; Mobile; rv:13.0) Gecko/13.0 Firefox/13.0';
         $this->agent->parse($newAgent);
@@ -93,7 +93,7 @@ public function testParse()
         $this->assertTrue($this->agent->isMobile('android'));
     }
 
-    public function testParseBot()
+    public function testParseBot(): void
     {
         $newAgent = 'Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)';
         $this->agent->parse($newAgent);
@@ -104,7 +104,7 @@ public function testParseBot()
         $this->assertFalse($this->agent->isMobile());
     }
 
-    public function testEmptyUserAgentVariable()
+    public function testEmptyUserAgentVariable(): void
     {
         unset($_SERVER['HTTP_USER_AGENT']);
         $agent = new UserAgent();
diff --git a/tests/system/Helpers/ArrayHelperTest.php b/tests/system/Helpers/ArrayHelperTest.php
index 0202c8c8bf3c..53a860c3a4a4 100644
--- a/tests/system/Helpers/ArrayHelperTest.php
+++ b/tests/system/Helpers/ArrayHelperTest.php
@@ -28,7 +28,7 @@ protected function setUp(): void
         helper('array');
     }
 
-    public function testArrayDotSimple()
+    public function testArrayDotSimple(): void
     {
         $data = [
             'foo' => [
@@ -39,7 +39,7 @@ public function testArrayDotSimple()
         $this->assertSame(23, dot_array_search('foo.bar', $data));
     }
 
-    public function testArrayDotTooManyLevels()
+    public function testArrayDotTooManyLevels(): void
     {
         $data = [
             'foo' => [
@@ -50,7 +50,7 @@ public function testArrayDotTooManyLevels()
         $this->assertNull(dot_array_search('foo.bar.baz', $data));
     }
 
-    public function testArrayDotTooManyLevelsWithWildCard()
+    public function testArrayDotTooManyLevelsWithWildCard(): void
     {
         $data = [
             'a' => [],
@@ -62,7 +62,7 @@ public function testArrayDotTooManyLevelsWithWildCard()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5369
      */
-    public function testArrayDotValueIsListArray()
+    public function testArrayDotValueIsListArray(): void
     {
         $data = [
             'arr' => [1, 2, 3],
@@ -71,7 +71,7 @@ public function testArrayDotValueIsListArray()
         $this->assertNull(dot_array_search('arr.*.index', $data));
     }
 
-    public function testArrayDotEscape()
+    public function testArrayDotEscape(): void
     {
         $data = [
             'foo' => [
@@ -86,7 +86,7 @@ public function testArrayDotEscape()
         $this->assertSame(42, dot_array_search('foo\.bar.baz', $data));
     }
 
-    public function testArraySearchDotMultiLevels()
+    public function testArraySearchDotMultiLevels(): void
     {
         $data1 = [
             'bar' => [
@@ -109,14 +109,14 @@ public function testArraySearchDotMultiLevels()
         $this->assertNull(dot_array_search('bar.*.foo', $data3));
     }
 
-    public function testArrayDotReturnNullEmptyArray()
+    public function testArrayDotReturnNullEmptyArray(): void
     {
         $data = [];
 
         $this->assertNull(dot_array_search('foo.bar', $data));
     }
 
-    public function testArrayDotReturnNullMissingValue()
+    public function testArrayDotReturnNullMissingValue(): void
     {
         $data = [
             'foo' => [
@@ -127,7 +127,7 @@ public function testArrayDotReturnNullMissingValue()
         $this->assertNull(dot_array_search('foo.baz', $data));
     }
 
-    public function testArrayDotReturnNullEmptyIndex()
+    public function testArrayDotReturnNullEmptyIndex(): void
     {
         $data = [
             'foo' => [
@@ -138,7 +138,7 @@ public function testArrayDotReturnNullEmptyIndex()
         $this->assertNull(dot_array_search('', $data));
     }
 
-    public function testArrayDotEarlyIndex()
+    public function testArrayDotEarlyIndex(): void
     {
         $data = [
             'foo' => [
@@ -149,7 +149,7 @@ public function testArrayDotEarlyIndex()
         $this->assertSame(['bar' => 23], dot_array_search('foo', $data));
     }
 
-    public function testArrayDotWildcard()
+    public function testArrayDotWildcard(): void
     {
         $data = [
             'foo' => [
@@ -162,7 +162,7 @@ public function testArrayDotWildcard()
         $this->assertSame(23, dot_array_search('foo.*.baz', $data));
     }
 
-    public function testArrayDotWildcardWithMultipleChoices()
+    public function testArrayDotWildcardWithMultipleChoices(): void
     {
         $data = [
             'foo' => [
@@ -179,7 +179,7 @@ public function testArrayDotWildcardWithMultipleChoices()
         $this->assertSame(23, dot_array_search('foo.*.baz', $data));
     }
 
-    public function testArrayDotNestedNotFound()
+    public function testArrayDotNestedNotFound(): void
     {
         $data = [
             'foo' => [
@@ -195,7 +195,7 @@ public function testArrayDotNestedNotFound()
         $this->assertNull(dot_array_search('foo.*.notthere', $data));
     }
 
-    public function testArrayDotIgnoresLastWildcard()
+    public function testArrayDotIgnoresLastWildcard(): void
     {
         $data = [
             'foo' => [
@@ -214,7 +214,7 @@ public function testArrayDotIgnoresLastWildcard()
      * @param int|string        $key
      * @param array|string|null $expected
      */
-    public function testArrayDeepSearch($key, $expected)
+    public function testArrayDeepSearch($key, $expected): void
     {
         $data = [
             'key1' => 'Value 1',
@@ -240,7 +240,7 @@ public function testArrayDeepSearch($key, $expected)
         $this->assertSame($expected, $result);
     }
 
-    public function testArrayDeepSearchReturnNullEmptyArray()
+    public function testArrayDeepSearchReturnNullEmptyArray(): void
     {
         $data = [];
 
@@ -250,7 +250,7 @@ public function testArrayDeepSearchReturnNullEmptyArray()
     /**
      * @dataProvider sortByMultipleKeysProvider
      */
-    public function testArraySortByMultipleKeysWithArray(array $data, array $sortColumns, array $expected)
+    public function testArraySortByMultipleKeysWithArray(array $data, array $sortColumns, array $expected): void
     {
         $success = array_sort_by_multiple_keys($data, $sortColumns);
 
@@ -261,7 +261,7 @@ public function testArraySortByMultipleKeysWithArray(array $data, array $sortCol
     /**
      * @dataProvider sortByMultipleKeysProvider
      */
-    public function testArraySortByMultipleKeysWithObjects(array $data, array $sortColumns, array $expected)
+    public function testArraySortByMultipleKeysWithObjects(array $data, array $sortColumns, array $expected): void
     {
         // Morph to objects
         foreach ($data as $index => $dataSet) {
@@ -277,7 +277,7 @@ public function testArraySortByMultipleKeysWithObjects(array $data, array $sortC
     /**
      * @dataProvider sortByMultipleKeysProvider
      */
-    public function testArraySortByMultipleKeysFailsEmptyParameter(array $data, array $sortColumns, array $expected)
+    public function testArraySortByMultipleKeysFailsEmptyParameter(array $data, array $sortColumns, array $expected): void
     {
         // Both filled
         $success = array_sort_by_multiple_keys($data, $sortColumns);
@@ -301,7 +301,7 @@ public function testArraySortByMultipleKeysFailsEmptyParameter(array $data, arra
      *
      * @param mixed $data
      */
-    public function testArraySortByMultipleKeysFailsInconsistentArraySizes($data)
+    public function testArraySortByMultipleKeysFailsInconsistentArraySizes($data): void
     {
         // PHP 8 changes this error type
         if (version_compare(PHP_VERSION, '8.0', '<')) {
diff --git a/tests/system/Helpers/CookieHelperTest.php b/tests/system/Helpers/CookieHelperTest.php
index e20ae47742f9..45796658fecc 100755
--- a/tests/system/Helpers/CookieHelperTest.php
+++ b/tests/system/Helpers/CookieHelperTest.php
@@ -55,7 +55,7 @@ protected function setUp(): void
         helper('cookie');
     }
 
-    public function testSetCookie()
+    public function testSetCookie(): void
     {
         set_cookie($this->name, $this->value, $this->expire);
 
@@ -64,7 +64,7 @@ public function testSetCookie()
         delete_cookie($this->name);
     }
 
-    public function testHasCookie()
+    public function testHasCookie(): void
     {
         $cookieAttr = [
             'name'   => $this->name,
@@ -78,7 +78,7 @@ public function testHasCookie()
         delete_cookie($this->name);
     }
 
-    public function testSetCookieByArrayParameters()
+    public function testSetCookieByArrayParameters(): void
     {
         $cookieAttr = [
             'name'   => $this->name,
@@ -92,7 +92,7 @@ public function testSetCookieByArrayParameters()
         delete_cookie($this->name);
     }
 
-    public function testSetCookieConfigCookieIsUsed()
+    public function testSetCookieConfigCookieIsUsed(): void
     {
         /** @var Cookie $config */
         $config           = config('Cookie');
@@ -117,7 +117,7 @@ public function testSetCookieConfigCookieIsUsed()
         delete_cookie($this->name);
     }
 
-    public function testSetCookieSecured()
+    public function testSetCookieSecured(): void
     {
         $pre       = 'Hello, I try to';
         $pst       = 'your site';
@@ -136,7 +136,7 @@ public function testSetCookieSecured()
         delete_cookie($secured);
     }
 
-    public function testDeleteCookie()
+    public function testDeleteCookie(): void
     {
         $this->response->setCookie($this->name, $this->value, $this->expire);
 
@@ -149,14 +149,14 @@ public function testDeleteCookie()
         $this->assertSame(0, $cookie->getExpiresTimestamp());
     }
 
-    public function testGetCookie()
+    public function testGetCookie(): void
     {
         $_COOKIE['TEST'] = '5';
 
         $this->assertSame('5', get_cookie('TEST'));
     }
 
-    public function testGetCookieDefaultPrefix()
+    public function testGetCookieDefaultPrefix(): void
     {
         $_COOKIE['prefix_TEST'] = '5';
 
@@ -167,7 +167,7 @@ public function testGetCookieDefaultPrefix()
         $this->assertSame('5', get_cookie('TEST', false, ''));
     }
 
-    public function testGetCookiePrefix()
+    public function testGetCookiePrefix(): void
     {
         $_COOKIE['abc_TEST'] = '5';
 
@@ -178,7 +178,7 @@ public function testGetCookiePrefix()
         $this->assertSame('5', get_cookie('TEST', false, 'abc_'));
     }
 
-    public function testGetCookieNoPrefix()
+    public function testGetCookieNoPrefix(): void
     {
         $_COOKIE['abc_TEST'] = '5';
 
@@ -189,7 +189,7 @@ public function testGetCookieNoPrefix()
         $this->assertSame('5', get_cookie('abc_TEST', false, null));
     }
 
-    public function testDeleteCookieAfterLastSet()
+    public function testDeleteCookieAfterLastSet(): void
     {
         delete_cookie($this->name);
 
@@ -198,7 +198,7 @@ public function testDeleteCookieAfterLastSet()
         $this->assertSame('', $cookie->getValue());
     }
 
-    public function testSameSiteDefault()
+    public function testSameSiteDefault(): void
     {
         $cookieAttr = [
             'name'   => $this->name,
@@ -215,7 +215,7 @@ public function testSameSiteDefault()
         delete_cookie($this->name);
     }
 
-    public function testSameSiteInvalid()
+    public function testSameSiteInvalid(): void
     {
         $cookieAttr = [
             'name'     => $this->name,
@@ -230,7 +230,7 @@ public function testSameSiteInvalid()
         set_cookie($cookieAttr);
     }
 
-    public function testSameSiteParamArray()
+    public function testSameSiteParamArray(): void
     {
         $cookieAttr = [
             'name'     => $this->name,
@@ -248,7 +248,7 @@ public function testSameSiteParamArray()
         delete_cookie($this->name);
     }
 
-    public function testSameSiteParam()
+    public function testSameSiteParam(): void
     {
         set_cookie($this->name, $this->value, $this->expire, '', '', '', '', '', 'Strict');
 
diff --git a/tests/system/Helpers/DateHelperTest.php b/tests/system/Helpers/DateHelperTest.php
index 0637c7fab5a3..475c9002b6d4 100644
--- a/tests/system/Helpers/DateHelperTest.php
+++ b/tests/system/Helpers/DateHelperTest.php
@@ -28,7 +28,7 @@ protected function setUp(): void
         helper('date');
     }
 
-    public function testNowDefault()
+    public function testNowDefault(): void
     {
         Time::setTestNow('June 20, 2022', 'America/Chicago');
 
@@ -37,7 +37,7 @@ public function testNowDefault()
         Time::setTestNow();
     }
 
-    public function testNowSpecific()
+    public function testNowSpecific(): void
     {
         Time::setTestNow('June 20, 2022', 'America/Chicago');
 
@@ -50,7 +50,7 @@ public function testNowSpecific()
         Time::setTestNow();
     }
 
-    public function testTimezoneSelectDefault()
+    public function testTimezoneSelectDefault(): void
     {
         $timezones = DateTimeZone::listIdentifiers(DateTimeZone::ALL, null);
 
@@ -66,7 +66,7 @@ public function testTimezoneSelectDefault()
         $this->assertSame($expected, timezone_select('custom-select', 'Asia/Jakarta'));
     }
 
-    public function testTimezoneSelectSpecific()
+    public function testTimezoneSelectSpecific(): void
     {
         $spesificRegion = DateTimeZone::ASIA;
         $timezones      = DateTimeZone::listIdentifiers($spesificRegion, null);
@@ -86,7 +86,7 @@ public function testTimezoneSelectSpecific()
         );
     }
 
-    public function testTimezoneSelectSingle()
+    public function testTimezoneSelectSingle(): void
     {
         $spesificRegion = DateTimeZone::PER_COUNTRY;
         $country        = 'ID';
diff --git a/tests/system/Helpers/FilesystemHelperTest.php b/tests/system/Helpers/FilesystemHelperTest.php
index 5f35a7e40d07..e92505cc8a91 100644
--- a/tests/system/Helpers/FilesystemHelperTest.php
+++ b/tests/system/Helpers/FilesystemHelperTest.php
@@ -48,7 +48,7 @@ protected function setUp(): void
         helper('filesystem');
     }
 
-    public function testDirectoryMapDefaults()
+    public function testDirectoryMapDefaults(): void
     {
         $this->assertTrue(function_exists('directory_map'));
 
@@ -71,7 +71,7 @@ public function testDirectoryMapDefaults()
         $this->assertSame($expected, directory_map(vfsStream::url('root')));
     }
 
-    public function testDirectoryMapShowsHiddenFiles()
+    public function testDirectoryMapShowsHiddenFiles(): void
     {
         $this->assertTrue(function_exists('directory_map'));
 
@@ -95,7 +95,7 @@ public function testDirectoryMapShowsHiddenFiles()
         $this->assertSame($expected, directory_map(vfsStream::url('root'), false, true));
     }
 
-    public function testDirectoryMapLimitsRecursion()
+    public function testDirectoryMapLimitsRecursion(): void
     {
         $this->assertTrue(function_exists('directory_map'));
 
@@ -113,12 +113,12 @@ public function testDirectoryMapLimitsRecursion()
         $this->assertSame($expected, directory_map(vfsStream::url('root'), 1, true));
     }
 
-    public function testDirectoryMapHandlesNotfound()
+    public function testDirectoryMapHandlesNotfound(): void
     {
         $this->assertSame([], directory_map(SUPPORTPATH . 'Files/shaker/'));
     }
 
-    public function testDirectoryMirror()
+    public function testDirectoryMirror(): void
     {
         $this->assertTrue(function_exists('directory_mirror'));
 
@@ -134,7 +134,7 @@ public function testDirectoryMirror()
         $this->assertFileExists($root . 'boo/bam/zab');
     }
 
-    public function testDirectoryMirrorOverwrites()
+    public function testDirectoryMirrorOverwrites(): void
     {
         $this->assertTrue(function_exists('directory_mirror'));
 
@@ -151,7 +151,7 @@ public function testDirectoryMirrorOverwrites()
         $this->assertSame($this->structure['foo']['faz'], $result);
     }
 
-    public function testDirectoryMirrorNotOverwrites()
+    public function testDirectoryMirrorNotOverwrites(): void
     {
         $this->assertTrue(function_exists('directory_mirror'));
 
@@ -168,7 +168,7 @@ public function testDirectoryMirrorNotOverwrites()
         $this->assertSame($this->structure['boo']['faz'], $result);
     }
 
-    public function testDirectoryMirrorSkipExistingFolder()
+    public function testDirectoryMirrorSkipExistingFolder(): void
     {
         $this->assertTrue(function_exists('directory_mirror'));
 
@@ -196,7 +196,7 @@ public function testDirectoryMirrorSkipExistingFolder()
         $this->assertSame([], $structure['root']['dest']['AnEmptyFolder']);
     }
 
-    public function testWriteFileSuccess()
+    public function testWriteFileSuccess(): void
     {
         $vfs = vfsStream::setup('root');
 
@@ -204,14 +204,14 @@ public function testWriteFileSuccess()
         $this->assertFileExists($vfs->getChild('test.php')->url());
     }
 
-    public function testWriteFileFailure()
+    public function testWriteFileFailure(): void
     {
         vfsStream::setup('root');
 
         $this->assertFalse(write_file(vfsStream::url('apple#test.php'), 'Simple'));
     }
 
-    public function testDeleteFilesDefaultsToOneLevelDeep()
+    public function testDeleteFilesDefaultsToOneLevelDeep(): void
     {
         $this->assertTrue(function_exists('delete_files'));
 
@@ -226,7 +226,7 @@ public function testDeleteFilesDefaultsToOneLevelDeep()
         $this->assertTrue($vfs->hasChild('AnEmptyFolder'));
     }
 
-    public function testDeleteFilesHandlesRecursion()
+    public function testDeleteFilesHandlesRecursion(): void
     {
         $this->assertTrue(function_exists('delete_files'));
 
@@ -241,7 +241,7 @@ public function testDeleteFilesHandlesRecursion()
         $this->assertFalse($vfs->hasChild('AnEmptyFolder'));
     }
 
-    public function testDeleteFilesLeavesHTFiles()
+    public function testDeleteFilesLeavesHTFiles(): void
     {
         $structure = array_merge($this->structure, [
             '.htaccess'  => 'Deny All',
@@ -263,7 +263,7 @@ public function testDeleteFilesLeavesHTFiles()
         $this->assertTrue($vfs->hasChild('index.php'));
     }
 
-    public function testDeleteFilesIncludingHidden()
+    public function testDeleteFilesIncludingHidden(): void
     {
         $structure = array_merge($this->structure, [
             '.htaccess'  => 'Deny All',
@@ -285,12 +285,12 @@ public function testDeleteFilesIncludingHidden()
         $this->assertTrue($vfs->hasChild('index.php'));
     }
 
-    public function testDeleteFilesFailure()
+    public function testDeleteFilesFailure(): void
     {
         $this->assertFalse(delete_files(SUPPORTPATH . 'Files/shaker/'));
     }
 
-    public function testGetFilenames()
+    public function testGetFilenames(): void
     {
         $this->assertTrue(function_exists('get_filenames'));
 
@@ -312,7 +312,7 @@ public function testGetFilenames()
         $this->assertSame($expected, get_filenames($vfs->url(), false));
     }
 
-    public function testGetFilenamesWithoutDirectories()
+    public function testGetFilenamesWithoutDirectories(): void
     {
         $vfs = vfsStream::setup('root', null, $this->structure);
 
@@ -328,7 +328,7 @@ public function testGetFilenamesWithoutDirectories()
         $this->assertSame($expected, $filenames);
     }
 
-    public function testGetFilenamesWithHidden()
+    public function testGetFilenamesWithHidden(): void
     {
         $this->assertTrue(function_exists('get_filenames'));
 
@@ -351,7 +351,7 @@ public function testGetFilenamesWithHidden()
         $this->assertSame($expected, get_filenames($vfs->url(), false, true));
     }
 
-    public function testGetFilenamesWithRelativeSource()
+    public function testGetFilenamesWithRelativeSource(): void
     {
         $this->assertTrue(function_exists('get_filenames'));
 
@@ -371,7 +371,7 @@ public function testGetFilenamesWithRelativeSource()
         $this->assertSame($expected, get_filenames($vfs->url(), null));
     }
 
-    public function testGetFilenamesWithFullSource()
+    public function testGetFilenamesWithFullSource(): void
     {
         $this->assertTrue(function_exists('get_filenames'));
 
@@ -391,12 +391,12 @@ public function testGetFilenamesWithFullSource()
         $this->assertSame($expected, get_filenames($vfs->url(), true));
     }
 
-    public function testGetFilenamesFailure()
+    public function testGetFilenamesFailure(): void
     {
         $this->assertSame([], get_filenames(SUPPORTPATH . 'Files/shaker/'));
     }
 
-    public function testGetDirFileInfo()
+    public function testGetDirFileInfo(): void
     {
         $file = SUPPORTPATH . 'Files/baker/banana.php';
         $info = get_file_info($file);
@@ -414,7 +414,7 @@ public function testGetDirFileInfo()
         $this->assertSame($expected, get_dir_file_info(SUPPORTPATH . 'Files/baker'));
     }
 
-    public function testGetDirFileInfoNested()
+    public function testGetDirFileInfoNested(): void
     {
         $expected = [
             'banana.php',
@@ -427,14 +427,14 @@ public function testGetDirFileInfoNested()
         $this->assertEmpty(array_diff($expected, array_keys($results)));
     }
 
-    public function testGetDirFileInfoFailure()
+    public function testGetDirFileInfoFailure(): void
     {
         $expected = [];
 
         $this->assertSame($expected, get_dir_file_info(SUPPORTPATH . 'Files#baker'));
     }
 
-    public function testGetFileInfo()
+    public function testGetFileInfo(): void
     {
         $file = SUPPORTPATH . 'Files/baker/banana.php';
         $info = get_file_info($file);
@@ -449,7 +449,7 @@ public function testGetFileInfo()
         $this->assertSame($expected, get_file_info(SUPPORTPATH . 'Files/baker/banana.php'));
     }
 
-    public function testGetFileInfoCustom()
+    public function testGetFileInfoCustom(): void
     {
         $expected = [
             'readable'   => true,
@@ -460,7 +460,7 @@ public function testGetFileInfoCustom()
         $this->assertSame($expected, get_file_info(SUPPORTPATH . 'Files/baker/banana.php', 'readable,writable,executable'));
     }
 
-    public function testGetFileInfoPerms()
+    public function testGetFileInfoPerms(): void
     {
         $file     = SUPPORTPATH . 'Files/baker/banana.php';
         $expected = 0664;
@@ -471,14 +471,14 @@ public function testGetFileInfoPerms()
         $this->assertSame($expected, $stuff['fileperms'] & 0777);
     }
 
-    public function testGetFileNotThereInfo()
+    public function testGetFileNotThereInfo(): void
     {
         $expected = null;
 
         $this->assertSame($expected, get_file_info(SUPPORTPATH . 'Files/icer'));
     }
 
-    public function testSameFileSame()
+    public function testSameFileSame(): void
     {
         $file1 = SUPPORTPATH . 'Files/able/apple.php';
         $file2 = SUPPORTPATH . 'Files/able/apple.php';
@@ -486,7 +486,7 @@ public function testSameFileSame()
         $this->assertTrue(same_file($file1, $file2));
     }
 
-    public function testSameFileIdentical()
+    public function testSameFileIdentical(): void
     {
         $file1 = SUPPORTPATH . 'Files/able/apple.php';
         $file2 = SUPPORTPATH . 'Files/baker/banana.php';
@@ -494,7 +494,7 @@ public function testSameFileIdentical()
         $this->assertTrue(same_file($file1, $file2));
     }
 
-    public function testSameFileDifferent()
+    public function testSameFileDifferent(): void
     {
         $file1 = SUPPORTPATH . 'Files/able/apple.php';
         $file2 = SUPPORTPATH . 'Images/ci-logo.gif';
@@ -502,7 +502,7 @@ public function testSameFileDifferent()
         $this->assertFalse(same_file($file1, $file2));
     }
 
-    public function testSameFileOrder()
+    public function testSameFileOrder(): void
     {
         $file1 = SUPPORTPATH . 'Files/able/apple.php';
         $file2 = SUPPORTPATH . 'Images/ci-logo.gif';
@@ -510,7 +510,7 @@ public function testSameFileOrder()
         $this->assertFalse(same_file($file2, $file1));
     }
 
-    public function testSameFileDirectory()
+    public function testSameFileDirectory(): void
     {
         $file1 = SUPPORTPATH . 'Files/able/apple.php';
         $file2 = SUPPORTPATH . 'Images/';
@@ -518,14 +518,14 @@ public function testSameFileDirectory()
         $this->assertFalse(same_file($file1, $file2));
     }
 
-    public function testOctalPermissions()
+    public function testOctalPermissions(): void
     {
         $this->assertSame('777', octal_permissions(0777));
         $this->assertSame('655', octal_permissions(0655));
         $this->assertSame('123', octal_permissions(0123));
     }
 
-    public function testSymbolicPermissions()
+    public function testSymbolicPermissions(): void
     {
         $expected = [
             0777    => 'urwxrwxrwx',
@@ -545,19 +545,19 @@ public function testSymbolicPermissions()
         }
     }
 
-    public function testRealPathURL()
+    public function testRealPathURL(): void
     {
         $this->expectException('InvalidArgumentException');
         set_realpath('http://somewhere.com/overtherainbow');
     }
 
-    public function testRealPathInvalid()
+    public function testRealPathInvalid(): void
     {
         $this->expectException('InvalidArgumentException');
         set_realpath(SUPPORTPATH . 'root/../', true);
     }
 
-    public function testRealPathResolved()
+    public function testRealPathResolved(): void
     {
         $this->assertSame(SUPPORTPATH . 'Models/', set_realpath(SUPPORTPATH . 'Files/../Models', true));
     }
diff --git a/tests/system/Helpers/FormHelperTest.php b/tests/system/Helpers/FormHelperTest.php
index 9a525adf7ad2..639d03c48f47 100644
--- a/tests/system/Helpers/FormHelperTest.php
+++ b/tests/system/Helpers/FormHelperTest.php
@@ -46,7 +46,7 @@ private function setRequest(): void
         Services::injectMock('request', $request);
     }
 
-    public function testFormOpenBasic()
+    public function testFormOpenBasic(): void
     {
         $this->setRequest();
 
@@ -74,7 +74,7 @@ public function testFormOpenBasic()
         $this->assertSame($expected, form_open('foo/bar', $attributes));
     }
 
-    public function testFormOpenHasLocale()
+    public function testFormOpenHasLocale(): void
     {
         $this->setRequest();
 
@@ -91,7 +91,7 @@ public function testFormOpenHasLocale()
         $this->assertSame($expected, form_open('{locale}/foo/bar', $attributes));
     }
 
-    public function testFormOpenWithoutAction()
+    public function testFormOpenWithoutAction(): void
     {
         $this->setRequest();
 
@@ -118,7 +118,7 @@ public function testFormOpenWithoutAction()
         $this->assertSame($expected, form_open('', $attributes));
     }
 
-    public function testFormOpenWithoutMethod()
+    public function testFormOpenWithoutMethod(): void
     {
         $this->setRequest();
 
@@ -145,7 +145,7 @@ public function testFormOpenWithoutMethod()
         $this->assertSame($expected, form_open('foo/bar', $attributes));
     }
 
-    public function testFormOpenWithHidden()
+    public function testFormOpenWithHidden(): void
     {
         $this->setRequest();
 
@@ -179,7 +179,7 @@ public function testFormOpenWithHidden()
         $this->assertSame($expected, form_open('foo/bar', $attributes, $hidden));
     }
 
-    public function testFormOpenMultipart()
+    public function testFormOpenMultipart(): void
     {
         $this->setRequest();
 
@@ -210,7 +210,7 @@ public function testFormOpenMultipart()
         $this->assertSame($expected, form_open_multipart('foo/bar', $attributesString));
     }
 
-    public function testFormHidden()
+    public function testFormHidden(): void
     {
         $expected = <<<EOH
 
@@ -219,7 +219,7 @@ public function testFormHidden()
         $this->assertSame($expected, form_hidden('username', 'johndoe'));
     }
 
-    public function testFormHiddenArrayInput()
+    public function testFormHiddenArrayInput(): void
     {
         $data = [
             'foo' => 'bar',
@@ -232,7 +232,7 @@ public function testFormHiddenArrayInput()
         $this->assertSame($expected, form_hidden($data, null));
     }
 
-    public function testFormHiddenArrayValues()
+    public function testFormHiddenArrayValues(): void
     {
         $data = [
             'foo' => 'bar',
@@ -245,7 +245,7 @@ public function testFormHiddenArrayValues()
         $this->assertSame($expected, form_hidden('name', $data));
     }
 
-    public function testFormInput()
+    public function testFormInput(): void
     {
         $expected = <<<EOH
             <input type="text" name="username" value="johndoe" id="username" maxlength="100" size="50" style="width:50%">\n
@@ -261,7 +261,7 @@ public function testFormInput()
         $this->assertSame($expected, form_input($data));
     }
 
-    public function testFormInputXHTML()
+    public function testFormInputXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -284,7 +284,7 @@ public function testFormInputXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testFormInputWithExtra()
+    public function testFormInputWithExtra(): void
     {
         $expected = <<<EOH
             <input type="email" name="identity" value="" id="identity" class="form-control form-control-lg">\n
@@ -300,7 +300,7 @@ public function testFormInputWithExtra()
         $this->assertSame($expected, form_input($data, '', $extra));
     }
 
-    public function testFormPassword()
+    public function testFormPassword(): void
     {
         $expected = <<<EOH
             <input type="password" name="password" value="">\n
@@ -308,7 +308,7 @@ public function testFormPassword()
         $this->assertSame($expected, form_password('password'));
     }
 
-    public function testFormUpload()
+    public function testFormUpload(): void
     {
         $expected = <<<EOH
             <input type="file" name="attachment">\n
@@ -316,7 +316,7 @@ public function testFormUpload()
         $this->assertSame($expected, form_upload('attachment'));
     }
 
-    public function testFormUploadXHTML()
+    public function testFormUploadXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -331,7 +331,7 @@ public function testFormUploadXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testFormTextarea()
+    public function testFormTextarea(): void
     {
         $expected = <<<EOH
             <textarea name="notes" cols="40" rows="10">Notes</textarea>\n
@@ -339,7 +339,7 @@ public function testFormTextarea()
         $this->assertSame($expected, form_textarea('notes', 'Notes'));
     }
 
-    public function testFormTextareaWithValueAttribute()
+    public function testFormTextareaWithValueAttribute(): void
     {
         $data = [
             'name'  => 'foo',
@@ -352,7 +352,7 @@ public function testFormTextareaWithValueAttribute()
         $this->assertSame($expected, form_textarea($data));
     }
 
-    public function testFormTextareaExtraRowsColsArray()
+    public function testFormTextareaExtraRowsColsArray(): void
     {
         $extra = [
             'cols' => '30',
@@ -364,7 +364,7 @@ public function testFormTextareaExtraRowsColsArray()
         $this->assertSame($expected, form_textarea('notes', 'Notes', $extra));
     }
 
-    public function testFormTextareaExtraRowsColsString()
+    public function testFormTextareaExtraRowsColsString(): void
     {
         $extra    = 'cols="30" rows="5"';
         $expected = <<<EOH
@@ -373,7 +373,7 @@ public function testFormTextareaExtraRowsColsString()
         $this->assertSame($expected, form_textarea('notes', 'Notes', $extra));
     }
 
-    public function testFormDropdown()
+    public function testFormDropdown(): void
     {
         $expected = <<<EOH
             <select name="shirts">
@@ -428,7 +428,7 @@ public function testFormDropdown()
         $this->assertSame($expected, form_dropdown('cars', $options, ['volvo', 'audi']));
     }
 
-    public function testFormDropdownUnselected()
+    public function testFormDropdownUnselected(): void
     {
         $options = [
             'Swedish Cars' => [
@@ -455,7 +455,7 @@ public function testFormDropdownUnselected()
         $this->assertSame($expected, form_dropdown('cars', $options));
     }
 
-    public function testFormDropdownKeyCasting()
+    public function testFormDropdownKeyCasting(): void
     {
         $options = [
             'Swedish Cars' => [
@@ -483,7 +483,7 @@ public function testFormDropdownKeyCasting()
         $this->assertSame($expected, form_dropdown('cars', $options, $selected));
     }
 
-    public function testFormDropdownInferred()
+    public function testFormDropdownInferred(): void
     {
         $options = [
             'Swedish Cars' => [
@@ -512,7 +512,7 @@ public function testFormDropdownInferred()
         unset($_POST['cars']);
     }
 
-    public function testFormDropdownWithSelectedAttribute()
+    public function testFormDropdownWithSelectedAttribute(): void
     {
         $expected = <<<'EOH'
             <select name="foo">
@@ -530,7 +530,7 @@ public function testFormDropdownWithSelectedAttribute()
         $this->assertSame($expected, form_dropdown($data, $options));
     }
 
-    public function testFormDropdownWithOptionsAttribute()
+    public function testFormDropdownWithOptionsAttribute(): void
     {
         $expected = <<<'EOH'
             <select name="foo">
@@ -547,7 +547,7 @@ public function testFormDropdownWithOptionsAttribute()
         $this->assertSame($expected, form_dropdown($data));
     }
 
-    public function testFormDropdownWithEmptyArrayOptionValue()
+    public function testFormDropdownWithEmptyArrayOptionValue(): void
     {
         $expected = <<<'EOH'
             <select name="foo">
@@ -560,7 +560,7 @@ public function testFormDropdownWithEmptyArrayOptionValue()
         $this->assertSame($expected, form_dropdown('foo', $options));
     }
 
-    public function testFormMultiselect()
+    public function testFormMultiselect(): void
     {
         $expected = <<<EOH
             <select name="shirts[]"  multiple="multiple">
@@ -579,7 +579,7 @@ public function testFormMultiselect()
         $this->assertSame($expected, form_multiselect('shirts[]', $options, ['med', 'large']));
     }
 
-    public function testFormMultiselectArrayData()
+    public function testFormMultiselectArrayData(): void
     {
         $expected = <<<EOH
             <select name="shirts[]"  multiple="multiple">
@@ -608,7 +608,7 @@ public function testFormMultiselectArrayData()
         $this->assertSame($expected, form_multiselect($data));
     }
 
-    public function testFormFieldset()
+    public function testFormFieldset(): void
     {
         $expected = <<<EOH
             <fieldset>
@@ -617,7 +617,7 @@ public function testFormFieldset()
         $this->assertSame($expected, form_fieldset('Address Information'));
     }
 
-    public function testFormFieldsetWithNoLegent()
+    public function testFormFieldsetWithNoLegent(): void
     {
         $expected = <<<'EOH'
             <fieldset>
@@ -626,7 +626,7 @@ public function testFormFieldsetWithNoLegent()
         $this->assertSame($expected, form_fieldset());
     }
 
-    public function testFormFieldsetWithAttributes()
+    public function testFormFieldsetWithAttributes(): void
     {
         $attributes = [
             'name' => 'bar',
@@ -639,7 +639,7 @@ public function testFormFieldsetWithAttributes()
         $this->assertSame($expected, form_fieldset('Foo', $attributes));
     }
 
-    public function testFormFieldsetClose()
+    public function testFormFieldsetClose(): void
     {
         $expected = <<<'EOH'
             </fieldset></div></div>
@@ -647,7 +647,7 @@ public function testFormFieldsetClose()
         $this->assertSame($expected, form_fieldset_close('</div></div>'));
     }
 
-    public function testFormCheckbox()
+    public function testFormCheckbox(): void
     {
         $expected = <<<EOH
             <input type="checkbox" name="newsletter" value="accept" checked="checked">\n
@@ -655,7 +655,7 @@ public function testFormCheckbox()
         $this->assertSame($expected, form_checkbox('newsletter', 'accept', true));
     }
 
-    public function testFormCheckboxXHTML()
+    public function testFormCheckboxXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -670,7 +670,7 @@ public function testFormCheckboxXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testFormCheckboxArrayData()
+    public function testFormCheckboxArrayData(): void
     {
         $data = [
             'name'    => 'foo',
@@ -684,7 +684,7 @@ public function testFormCheckboxArrayData()
         $this->assertSame($expected, form_checkbox($data));
     }
 
-    public function testFormCheckboxArrayDataWithCheckedFalse()
+    public function testFormCheckboxArrayDataWithCheckedFalse(): void
     {
         $data = [
             'name'    => 'foo',
@@ -698,7 +698,7 @@ public function testFormCheckboxArrayDataWithCheckedFalse()
         $this->assertSame($expected, form_checkbox($data));
     }
 
-    public function testFormRadio()
+    public function testFormRadio(): void
     {
         $expected = <<<EOH
             <input type="radio" name="newsletter" value="accept" checked="checked">\n
@@ -706,7 +706,7 @@ public function testFormRadio()
         $this->assertSame($expected, form_radio('newsletter', 'accept', true));
     }
 
-    public function testFormSubmit()
+    public function testFormSubmit(): void
     {
         $expected = <<<EOH
             <input type="submit" name="mysubmit" value="Submit Post!">\n
@@ -714,7 +714,7 @@ public function testFormSubmit()
         $this->assertSame($expected, form_submit('mysubmit', 'Submit Post!'));
     }
 
-    public function testFormLabel()
+    public function testFormLabel(): void
     {
         $expected = <<<'EOH'
             <label for="username">What is your Name</label>
@@ -722,7 +722,7 @@ public function testFormLabel()
         $this->assertSame($expected, form_label('What is your Name', 'username'));
     }
 
-    public function testFormLabelWithAttributes()
+    public function testFormLabelWithAttributes(): void
     {
         $attributes = [
             'id' => 'label1',
@@ -733,7 +733,7 @@ public function testFormLabelWithAttributes()
         $this->assertSame($expected, form_label('bar', 'foo', $attributes));
     }
 
-    public function testFormReset()
+    public function testFormReset(): void
     {
         $expected = <<<EOH
             <input type="reset" name="myreset" value="Reset">\n
@@ -741,7 +741,7 @@ public function testFormReset()
         $this->assertSame($expected, form_reset('myreset', 'Reset'));
     }
 
-    public function testFormButton()
+    public function testFormButton(): void
     {
         $expected = <<<EOH
             <button name="name" type="button">content</button>\n
@@ -749,7 +749,7 @@ public function testFormButton()
         $this->assertSame($expected, form_button('name', 'content'));
     }
 
-    public function testFormButtonWithDataArray()
+    public function testFormButtonWithDataArray(): void
     {
         $data = [
             'name'    => 'foo',
@@ -762,7 +762,7 @@ public function testFormButtonWithDataArray()
         $this->assertSame($expected, form_button($data));
     }
 
-    public function testFormClose()
+    public function testFormClose(): void
     {
         $expected = <<<'EOH'
             </form></div></div>
@@ -770,7 +770,7 @@ public function testFormClose()
         $this->assertSame($expected, form_close('</div></div>'));
     }
 
-    public function testFormDatalist()
+    public function testFormDatalist(): void
     {
         $options = [
             'foo1',
@@ -787,7 +787,7 @@ public function testFormDatalist()
         $this->assertSame($expected, form_datalist('foo', 'bar', $options));
     }
 
-    public function testSetValue()
+    public function testSetValue(): void
     {
         $_SESSION['_ci_old_input']['post']['foo'] = '<bar';
         $this->assertSame('&lt;bar', set_value('foo'));
@@ -796,7 +796,7 @@ public function testSetValue()
         $this->assertSame('baz', set_value('foo', 'baz'));
     }
 
-    public function testSetSelect()
+    public function testSetSelect(): void
     {
         $_SESSION['_ci_old_input']['post']['foo'] = 'bar';
         $this->assertSame(' selected="selected"', set_select('foo', 'bar'));
@@ -809,7 +809,7 @@ public function testSetSelect()
         $this->assertSame(' selected="selected"', set_select('foo', 'baz', true));
     }
 
-    public function testSetCheckbox()
+    public function testSetCheckbox(): void
     {
         $_SESSION = [
             '_ci_old_input' => [
@@ -838,7 +838,7 @@ public function testSetCheckbox()
         $this->assertSame(' checked="checked"', set_checkbox('foo', 'bar', true));
     }
 
-    public function testSetCheckboxWithValueZero()
+    public function testSetCheckboxWithValueZero(): void
     {
         $_SESSION = [
             '_ci_old_input' => [
@@ -871,7 +871,7 @@ public function testSetCheckboxWithValueZero()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSetRadioFromSessionOldInput()
+    public function testSetRadioFromSessionOldInput(): void
     {
         $_SESSION = [
             '_ci_old_input' => [
@@ -891,7 +891,7 @@ public function testSetRadioFromSessionOldInput()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSetRadioFromPost()
+    public function testSetRadioFromPost(): void
     {
         $_POST['bar'] = 'baz';
 
@@ -904,7 +904,7 @@ public function testSetRadioFromPost()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testSetRadioFromPostWithValueZero()
+    public function testSetRadioFromPostWithValueZero(): void
     {
         $_POST['bar'] = '0';
 
@@ -916,7 +916,7 @@ public function testSetRadioFromPostWithValueZero()
         $this->assertSame(' checked="checked"', set_radio('bar', '0', true));
     }
 
-    public function testSetRadioFromSessionOldInputPostArray()
+    public function testSetRadioFromSessionOldInputPostArray(): void
     {
         $_SESSION = [
             '_ci_old_input' => [
@@ -933,7 +933,7 @@ public function testSetRadioFromSessionOldInputPostArray()
         $this->assertSame('', set_radio('bar', 'baz'));
     }
 
-    public function testSetRadioFromSessionOldInputPostArrayWithValueZero()
+    public function testSetRadioFromSessionOldInputPostArrayWithValueZero(): void
     {
         $_SESSION = [
             '_ci_old_input' => [
@@ -950,7 +950,7 @@ public function testSetRadioFromSessionOldInputPostArrayWithValueZero()
         $this->assertSame('', set_radio('bar', 'baz'));
     }
 
-    public function testSetRadioDefault()
+    public function testSetRadioDefault(): void
     {
         $_SESSION = [];
         $_POST    = [];
@@ -959,7 +959,7 @@ public function testSetRadioDefault()
         $this->assertSame('', set_radio('code', 'beta', false));
     }
 
-    public function testValidationErrorsFromSession()
+    public function testValidationErrorsFromSession(): void
     {
         $_SESSION = ['_ci_validation_errors' => ['foo' => 'bar']];
 
@@ -968,7 +968,7 @@ public function testValidationErrorsFromSession()
         $_SESSION = [];
     }
 
-    public function testValidationErrorsFromValidation()
+    public function testValidationErrorsFromValidation(): void
     {
         $validation = Services::validation();
         $validation->setRule('id', 'ID', 'required')->run([]);
@@ -976,7 +976,7 @@ public function testValidationErrorsFromValidation()
         $this->assertSame(['id' => 'The ID field is required.'], validation_errors());
     }
 
-    public function testValidationListErrors()
+    public function testValidationListErrors(): void
     {
         $validation = Services::validation();
         $validation->setRule('id', 'ID', 'required')->run([]);
@@ -986,7 +986,7 @@ public function testValidationListErrors()
         $this->assertStringContainsString('<li>The ID field is required.</li>', $html);
     }
 
-    public function testValidationShowError()
+    public function testValidationShowError(): void
     {
         $validation = Services::validation();
         $validation->setRule('id', 'ID', 'required')->run([]);
@@ -996,7 +996,7 @@ public function testValidationShowError()
         $this->assertSame('<span class="help-block">The ID field is required.</span>' . "\n", $html);
     }
 
-    public function testValidationShowErrorForWildcards()
+    public function testValidationShowErrorForWildcards(): void
     {
         $validation = Services::validation();
         $validation->setRule('user.*.name', 'Name', 'required')
@@ -1015,43 +1015,43 @@ public function testValidationShowErrorForWildcards()
         $this->assertSame('<span class="help-block">The Name field is required.</span>' . "\n", $html);
     }
 
-    public function testFormParseFormAttributesTrue()
+    public function testFormParseFormAttributesTrue(): void
     {
         $expected = 'readonly ';
         $this->assertSame($expected, parse_form_attributes(['readonly' => true], []));
     }
 
-    public function testFormParseFormAttributesFalse()
+    public function testFormParseFormAttributesFalse(): void
     {
         $expected = 'disabled ';
         $this->assertSame($expected, parse_form_attributes(['disabled' => false], []));
     }
 
-    public function testFormParseFormAttributesNull()
+    public function testFormParseFormAttributesNull(): void
     {
         $expected = 'bar=""';
         $this->assertSame($expected, parse_form_attributes(['bar' => null], []));
     }
 
-    public function testFormParseFormAttributesStringEmpty()
+    public function testFormParseFormAttributesStringEmpty(): void
     {
         $expected = 'bar=""';
         $this->assertSame($expected, parse_form_attributes(['bar' => ''], []));
     }
 
-    public function testFormParseFormAttributesStringFoo()
+    public function testFormParseFormAttributesStringFoo(): void
     {
         $expected = 'bar="foo"';
         $this->assertSame($expected, parse_form_attributes(['bar' => 'foo'], []));
     }
 
-    public function testFormParseFormAttributesInt0()
+    public function testFormParseFormAttributesInt0(): void
     {
         $expected = 'ok="0"';
         $this->assertSame($expected, parse_form_attributes(['ok' => 0], []));
     }
 
-    public function testFormParseFormAttributesInt1()
+    public function testFormParseFormAttributesInt1(): void
     {
         $expected = 'ok="1"';
         $this->assertSame($expected, parse_form_attributes(['ok' => 1], []));
diff --git a/tests/system/Helpers/HTMLHelperTest.php b/tests/system/Helpers/HTMLHelperTest.php
index 67a72666ced8..1f8485393b3f 100755
--- a/tests/system/Helpers/HTMLHelperTest.php
+++ b/tests/system/Helpers/HTMLHelperTest.php
@@ -47,7 +47,7 @@ protected function setUp(): void
         ];
     }
 
-    public function testBasicUL()
+    public function testBasicUL(): void
     {
         $expected = <<<'EOH'
             <ul>
@@ -66,7 +66,7 @@ public function testBasicUL()
         $this->assertSame(ltrim($expected), ul($list));
     }
 
-    public function testULWithClass()
+    public function testULWithClass(): void
     {
         $expected = <<<'EOH'
             <ul class="test">
@@ -85,7 +85,7 @@ public function testULWithClass()
         $this->assertSame($expected, ul($list, 'class="test"'));
     }
 
-    public function testMultiLevelUL()
+    public function testMultiLevelUL(): void
     {
         $expected = <<<'EOH'
             <ul>
@@ -114,7 +114,7 @@ public function testMultiLevelUL()
         $this->assertSame(ltrim($expected), ul($list));
     }
 
-    public function testBasicOL()
+    public function testBasicOL(): void
     {
         $expected = <<<'EOH'
             <ol>
@@ -133,7 +133,7 @@ public function testBasicOL()
         $this->assertSame(ltrim($expected), ol($list));
     }
 
-    public function testOLWithClass()
+    public function testOLWithClass(): void
     {
         $expected = <<<'EOH'
             <ol class="test">
@@ -152,7 +152,7 @@ public function testOLWithClass()
         $this->assertSame($expected, ol($list, 'class="test"'));
     }
 
-    public function testMultiLevelOL()
+    public function testMultiLevelOL(): void
     {
         $expected = <<<'EOH'
             <ol>
@@ -181,28 +181,28 @@ public function testMultiLevelOL()
         $this->assertSame(ltrim($expected), ol($list));
     }
 
-    public function testIMG()
+    public function testIMG(): void
     {
         $target   = 'http://site.com/images/picture.jpg';
         $expected = '<img src="http://site.com/images/picture.jpg" alt="">';
         $this->assertSame($expected, img($target));
     }
 
-    public function testIMGWithoutProtocol()
+    public function testIMGWithoutProtocol(): void
     {
         $target   = 'assets/mugshot.jpg';
         $expected = '<img src="http://example.com/assets/mugshot.jpg" alt="">';
         $this->assertSame($expected, img($target));
     }
 
-    public function testIMGWithIndexpage()
+    public function testIMGWithIndexpage(): void
     {
         $target   = 'assets/mugshot.jpg';
         $expected = '<img src="http://example.com/index.php/assets/mugshot.jpg" alt="">';
         $this->assertSame($expected, img($target, true));
     }
 
-    public function testIMGXHTML()
+    public function testIMGXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -215,7 +215,7 @@ public function testIMGXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testIMGXHTMLWithoutProtocol()
+    public function testIMGXHTMLWithoutProtocol(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -228,7 +228,7 @@ public function testIMGXHTMLWithoutProtocol()
         $doctypes->html5 = $default;
     }
 
-    public function testIMGXHTMLWithIndexpage()
+    public function testIMGXHTMLWithIndexpage(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -241,21 +241,21 @@ public function testIMGXHTMLWithIndexpage()
         $doctypes->html5 = $default;
     }
 
-    public function testImgData()
+    public function testImgData(): void
     {
         $expected = 'data:image/gif;base64,' . $this->imgData;
 
         $this->assertSame($expected, img_data($this->imgPath));
     }
 
-    public function testImgDataWithMime()
+    public function testImgDataWithMime(): void
     {
         $expected = 'data:image/png;base64,' . $this->imgData;
 
         $this->assertSame($expected, img_data($this->imgPath, 'image/png'));
     }
 
-    public function testImgDataUnknownMime()
+    public function testImgDataUnknownMime(): void
     {
         $path   = SUPPORTPATH . 'Validation' . DIRECTORY_SEPARATOR . 'uploads' . DIRECTORY_SEPARATOR . 'phpUxc0ty';
         $result = img_data($path);
@@ -263,56 +263,56 @@ public function testImgDataUnknownMime()
         $this->assertSame(0, strpos($result, 'data:image/jpg'));
     }
 
-    public function testImgDataNoFile()
+    public function testImgDataNoFile(): void
     {
         $this->expectException(FileNotFoundException::class);
 
         img_data($this->imgPath . 'gobbledygook');
     }
 
-    public function testScriptTag()
+    public function testScriptTag(): void
     {
         $target   = 'http://site.com/js/mystyles.js';
         $expected = '<script src="http://site.com/js/mystyles.js"></script>';
         $this->assertSame($expected, script_tag($target));
     }
 
-    public function testScriptTagWithoutProtocol()
+    public function testScriptTagWithoutProtocol(): void
     {
         $target   = 'js/mystyles.js';
         $expected = '<script src="http://example.com/js/mystyles.js"></script>';
         $this->assertSame($expected, script_tag($target));
     }
 
-    public function testScriptTagWithIndexpage()
+    public function testScriptTagWithIndexpage(): void
     {
         $target   = 'js/mystyles.js';
         $expected = '<script src="http://example.com/index.php/js/mystyles.js"></script>';
         $this->assertSame($expected, script_tag($target, true));
     }
 
-    public function testScriptTagWithSrc()
+    public function testScriptTagWithSrc(): void
     {
         $target   = ['src' => 'http://site.com/js/mystyles.js'];
         $expected = '<script src="http://site.com/js/mystyles.js"></script>';
         $this->assertSame($expected, script_tag($target));
     }
 
-    public function testScriptTagWithSrcWithoutProtocol()
+    public function testScriptTagWithSrcWithoutProtocol(): void
     {
         $target   = ['src' => 'js/mystyles.js'];
         $expected = '<script src="http://example.com/js/mystyles.js"></script>';
         $this->assertSame($expected, script_tag($target));
     }
 
-    public function testScriptTagWithSrcAndAttributes()
+    public function testScriptTagWithSrcAndAttributes(): void
     {
         $target   = ['src' => 'js/mystyles.js', 'charset' => 'UTF-8', 'defer' => '', 'async' => null];
         $expected = '<script src="http://example.com/js/mystyles.js" charset="UTF-8" defer="" async></script>';
         $this->assertSame($expected, script_tag($target));
     }
 
-    public function testScriptTagWithCsp()
+    public function testScriptTagWithCsp(): void
     {
         // Reset CSP object
         $this->resetServices();
@@ -338,20 +338,20 @@ public function testScriptTagWithCsp()
      * This test has probably no real-world value but may help detecting
      * a change in the default behaviour.
      */
-    public function testScriptTagWithoutAnyArg()
+    public function testScriptTagWithoutAnyArg(): void
     {
         $expected = '<script src="http://example.com/"></script>';
         $this->assertSame($expected, script_tag());
     }
 
-    public function testLinkTag()
+    public function testLinkTag(): void
     {
         $target   = 'css/mystyles.css';
         $expected = '<link href="http://example.com/css/mystyles.css" rel="stylesheet" type="text/css">';
         $this->assertSame($expected, link_tag($target));
     }
 
-    public function testLinkTagXHTML()
+    public function testLinkTagXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -365,7 +365,7 @@ public function testLinkTagXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testLinkTagMedia()
+    public function testLinkTagMedia(): void
     {
         $target = 'https://styles.com/css/mystyles.css';
         $tag    = link_tag($target, 'stylesheet', 'text/css', '', 'print');
@@ -374,7 +374,7 @@ public function testLinkTagMedia()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagTitle()
+    public function testLinkTagTitle(): void
     {
         $tag = link_tag('default.css', 'stylesheet', 'text/css', 'Default Style');
 
@@ -382,7 +382,7 @@ public function testLinkTagTitle()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagFavicon()
+    public function testLinkTagFavicon(): void
     {
         $tag = link_tag('favicon.ico', 'shortcut icon', 'image/ico');
 
@@ -390,7 +390,7 @@ public function testLinkTagFavicon()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagRss()
+    public function testLinkTagRss(): void
     {
         $tag = link_tag('feed', 'alternate', 'application/rss+xml', 'My RSS Feed');
 
@@ -398,7 +398,7 @@ public function testLinkTagRss()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagAlternate()
+    public function testLinkTagAlternate(): void
     {
         $tag = link_tag(
             'http://sp.example.com/',
@@ -412,7 +412,7 @@ public function testLinkTagAlternate()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagArrayAlternate()
+    public function testLinkTagArrayAlternate(): void
     {
         $tag = link_tag([
             'href'  => 'http://sp.example.com/',
@@ -424,7 +424,7 @@ public function testLinkTagArrayAlternate()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagCanonical()
+    public function testLinkTagCanonical(): void
     {
         $tag = link_tag('http://www.example.com/', 'canonical');
 
@@ -432,7 +432,7 @@ public function testLinkTagCanonical()
         $this->assertSame($expected, $tag);
     }
 
-    public function testLinkTagArray()
+    public function testLinkTagArray(): void
     {
         $parms = [
             'href'      => 'css/mystyles.css',
@@ -442,7 +442,7 @@ public function testLinkTagArray()
         $this->assertSame($expected, link_tag($parms));
     }
 
-    public function testLinkTagArrayHreflang()
+    public function testLinkTagArrayHreflang(): void
     {
         $tag = link_tag([
             'href'     => 'https://example.com/en',
@@ -454,26 +454,26 @@ public function testLinkTagArrayHreflang()
         $this->assertSame($expected, $tag);
     }
 
-    public function testDocType()
+    public function testDocType(): void
     {
         $target   = 'html4-strict';
         $expected = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">';
         $this->assertSame($expected, doctype($target));
     }
 
-    public function testDocTypeDefault()
+    public function testDocTypeDefault(): void
     {
         $expected = '<!DOCTYPE html>';
         $this->assertSame($expected, doctype());
     }
 
-    public function testDocTypeInvalid()
+    public function testDocTypeInvalid(): void
     {
         $target = 'good-guess';
         $this->assertEmpty(doctype($target));
     }
 
-    public function testVideo()
+    public function testVideo(): void
     {
         $expected = <<<'EOH'
             <video src="http://www.codeigniter.com/test.mp4" controls>
@@ -488,7 +488,7 @@ public function testVideo()
         $this->assertSame($expected, $video);
     }
 
-    public function testVideoWithTracks()
+    public function testVideoWithTracks(): void
     {
         $expected = <<<'EOH'
             <video src="http://example.com/test.mp4" controls>
@@ -505,7 +505,7 @@ public function testVideoWithTracks()
         $this->assertSame($expected, $video);
     }
 
-    public function testVideoWithTracksXHTML()
+    public function testVideoWithTracksXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -533,7 +533,7 @@ public function testVideoWithTracksXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testVideoWithTracksAndIndex()
+    public function testVideoWithTracksAndIndex(): void
     {
         $expected = <<<'EOH'
             <video src="http://example.com/index.php/test.mp4" controls>
@@ -550,7 +550,7 @@ public function testVideoWithTracksAndIndex()
         $this->assertSame($expected, $video);
     }
 
-    public function testVideoMultipleSources()
+    public function testVideoMultipleSources(): void
     {
         $expected = <<<'EOH'
             <video class="test" controls>
@@ -577,7 +577,7 @@ public function testVideoMultipleSources()
         $this->assertSame($expected, $video);
     }
 
-    public function testVideoMultipleSourcesXHTML()
+    public function testVideoMultipleSourcesXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -615,7 +615,7 @@ public function testVideoMultipleSourcesXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testAudio()
+    public function testAudio(): void
     {
         $expected = <<<'EOH'
             <audio id="test" controls>
@@ -638,7 +638,7 @@ public function testAudio()
         $this->assertSame($expected, $audio);
     }
 
-    public function testAudioXHTML()
+    public function testAudioXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -672,7 +672,7 @@ public function testAudioXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testAudioSimple()
+    public function testAudioSimple(): void
     {
         $expected = <<<'EOH'
             <audio src="http://example.com/sound.mpeg" type="audio/mpeg" id="test" controls>
@@ -688,7 +688,7 @@ public function testAudioSimple()
         $this->assertSame($expected, $audio);
     }
 
-    public function testAudioWithSource()
+    public function testAudioWithSource(): void
     {
         $expected = <<<'EOH'
             <audio src="http://codeigniter.com/sound.mpeg" type="audio/mpeg" id="test" controls>
@@ -704,7 +704,7 @@ public function testAudioWithSource()
         $this->assertSame($expected, $audio);
     }
 
-    public function testAudioWithIndex()
+    public function testAudioWithIndex(): void
     {
         $expected = <<<'EOH'
             <audio src="http://example.com/index.php/sound.mpeg" type="audio/mpeg" id="test" controls>
@@ -720,7 +720,7 @@ public function testAudioWithIndex()
         $this->assertSame($expected, $audio);
     }
 
-    public function testAudioWithTracks()
+    public function testAudioWithTracks(): void
     {
         $expected = <<<'EOH'
             <audio src="http://example.com/sound.mpeg" type="audio/mpeg" id="test" controls>
@@ -738,7 +738,7 @@ public function testAudioWithTracks()
         $this->assertSame($expected, $audio);
     }
 
-    public function testMediaNameOnly()
+    public function testMediaNameOnly(): void
     {
         $expected = <<<'EOH'
             <av>
@@ -748,7 +748,7 @@ public function testMediaNameOnly()
         $this->assertSame($expected, _media('av'));
     }
 
-    public function testMediaWithSources()
+    public function testMediaWithSources(): void
     {
         $expected = <<<'EOH'
             <av>
@@ -764,13 +764,13 @@ public function testMediaWithSources()
         $this->assertSame($expected, _media('av', $sources));
     }
 
-    public function testSource()
+    public function testSource(): void
     {
         $expected = '<source src="http://example.com/index.php/sound.mpeg" type="audio/mpeg">';
         $this->assertSame($expected, source('sound.mpeg', 'audio/mpeg', '', true));
     }
 
-    public function testSourceXHTML()
+    public function testSourceXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -783,7 +783,7 @@ public function testSourceXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testEmbed()
+    public function testEmbed(): void
     {
         $expected = <<<'EOH'
             <embed src="http://example.com/movie.mov" type="video/quicktime" class="test">
@@ -795,7 +795,7 @@ public function testEmbed()
         $this->assertSame($expected, $embed);
     }
 
-    public function testEmbedXHTML()
+    public function testEmbedXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -814,7 +814,7 @@ public function testEmbedXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testEmbedIndexed()
+    public function testEmbedIndexed(): void
     {
         $expected = <<<'EOH'
             <embed src="http://example.com/index.php/movie.mov" type="video/quicktime" class="test">
@@ -826,7 +826,7 @@ public function testEmbedIndexed()
         $this->assertSame($expected, $embed, '');
     }
 
-    public function testObject()
+    public function testObject(): void
     {
         $expected = <<<'EOH'
             <object data="http://example.com/movie.swf" class="test"></object>
@@ -839,7 +839,7 @@ public function testObject()
         $this->assertSame($expected, $object);
     }
 
-    public function testObjectWithParams()
+    public function testObjectWithParams(): void
     {
         $expected = <<<'EOH'
             <object data="http://example.com/movie.swf" class="test">
@@ -858,7 +858,7 @@ public function testObjectWithParams()
         $this->assertSame($expected, $object);
     }
 
-    public function testObjectWithParamsXHTML()
+    public function testObjectWithParamsXHTML(): void
     {
         $doctypes        = config('DocTypes');
         $default         = $doctypes->html5;
@@ -884,7 +884,7 @@ public function testObjectWithParamsXHTML()
         $doctypes->html5 = $default;
     }
 
-    public function testObjectIndexed()
+    public function testObjectIndexed(): void
     {
         $expected = <<<'EOH'
             <object data="http://example.com/index.php/movie.swf" class="test"></object>
diff --git a/tests/system/Helpers/InflectorHelperTest.php b/tests/system/Helpers/InflectorHelperTest.php
index 53f4ecfb5e80..1a0325f4ccaa 100755
--- a/tests/system/Helpers/InflectorHelperTest.php
+++ b/tests/system/Helpers/InflectorHelperTest.php
@@ -27,7 +27,7 @@ protected function setUp(): void
         helper('inflector');
     }
 
-    public function testSingular()
+    public function testSingular(): void
     {
         $strings = [
             'matrices'  => 'matrix',
@@ -64,7 +64,7 @@ public function testSingular()
         }
     }
 
-    public function testPlural()
+    public function testPlural(): void
     {
         $strings = [
             'searches'  => 'search',
@@ -100,7 +100,7 @@ public function testPlural()
         }
     }
 
-    public function testCounted()
+    public function testCounted(): void
     {
         $triplets = [
             [
@@ -156,7 +156,7 @@ public function testCounted()
         }
     }
 
-    public function testCamelize()
+    public function testCamelize(): void
     {
         $strings = [
             'hello from codeIgniter 4' => 'helloFromCodeIgniter4',
@@ -169,7 +169,7 @@ public function testCamelize()
         }
     }
 
-    public function testPascalize()
+    public function testPascalize(): void
     {
         $strings = [
             'hello from codeIgniter 4' => 'HelloFromCodeIgniter4',
@@ -182,7 +182,7 @@ public function testPascalize()
         }
     }
 
-    public function testUnderscore()
+    public function testUnderscore(): void
     {
         $strings = [
             'Hello From CodeIgniter 4' => 'Hello_From_CodeIgniter_4',
@@ -195,7 +195,7 @@ public function testUnderscore()
         }
     }
 
-    public function testHumanize()
+    public function testHumanize(): void
     {
         $underscored = [
             'Hello_From_CodeIgniter_4',
@@ -213,7 +213,7 @@ public function testHumanize()
         $this->assertSame($humanizedDash, $dashed[1]);
     }
 
-    public function testIsCountable()
+    public function testIsCountable(): void
     {
         $words = [
             'tip'        => 'advice',
@@ -230,7 +230,7 @@ public function testIsCountable()
         }
     }
 
-    public function testDasherize()
+    public function testDasherize(): void
     {
         $strings = [
             'hello_world'              => 'hello-world',
@@ -262,12 +262,12 @@ public function provideOrdinal(): iterable
     /**
      * @dataProvider provideOrdinal
      */
-    public function testOrdinal(string $suffix, int $number)
+    public function testOrdinal(string $suffix, int $number): void
     {
         $this->assertSame($suffix, ordinal($number));
     }
 
-    public function testOrdinalize()
+    public function testOrdinalize(): void
     {
         $suffixedNumbers = [
             '1st'  => 1,
@@ -288,7 +288,7 @@ public function testOrdinalize()
         }
     }
 
-    public function testDecamelizeToSnakeCase()
+    public function testDecamelizeToSnakeCase(): void
     {
         $strings = [
             'simpleTest'      => 'simple_test',
diff --git a/tests/system/Helpers/NumberHelperTest.php b/tests/system/Helpers/NumberHelperTest.php
index b9faed213888..e18a23b94435 100755
--- a/tests/system/Helpers/NumberHelperTest.php
+++ b/tests/system/Helpers/NumberHelperTest.php
@@ -27,7 +27,7 @@ protected function setUp(): void
         helper('number');
     }
 
-    public function testRomanNumber()
+    public function testRomanNumber(): void
     {
         $this->assertSame('XCVI', number_to_roman(96));
         $this->assertSame('MMDCCCXCV', number_to_roman(2895));
@@ -36,25 +36,25 @@ public function testRomanNumber()
         $this->assertSame('X', number_to_roman(10));
     }
 
-    public function testRomanNumberRange()
+    public function testRomanNumberRange(): void
     {
         $this->assertNull(number_to_roman(-1));
         $this->assertNull(number_to_roman(0));
         $this->assertNull(number_to_roman(4000));
     }
 
-    public function testFormatNumber()
+    public function testFormatNumber(): void
     {
         $this->assertSame('123,456', format_number(123456, 0, 'en_US'));
     }
 
-    public function testFormatNumberWithPrecision()
+    public function testFormatNumberWithPrecision(): void
     {
         $this->assertSame('123,456.8', format_number(123456.789, 1, 'en_US'));
         $this->assertSame('123,456.79', format_number(123456.789, 2, 'en_US'));
     }
 
-    public function testFormattingOptions()
+    public function testFormattingOptions(): void
     {
         $options = [
             'before' => '<<',
@@ -63,42 +63,42 @@ public function testFormattingOptions()
         $this->assertSame('<<123,456.79>>', format_number(123456.789, 2, 'en_US', $options));
     }
 
-    public function testNumberToSize()
+    public function testNumberToSize(): void
     {
         $this->assertSame('456 Bytes', number_to_size(456, 1, 'en_US'));
     }
 
-    public function testKbFormat()
+    public function testKbFormat(): void
     {
         $this->assertSame('4.5 KB', number_to_size(4567, 1, 'en_US'));
     }
 
-    public function testKbFormatMedium()
+    public function testKbFormatMedium(): void
     {
         $this->assertSame('44.6 KB', number_to_size(45678, 1, 'en_US'));
     }
 
-    public function testKbFormatLarge()
+    public function testKbFormatLarge(): void
     {
         $this->assertSame('446.1 KB', number_to_size(456789, 1, 'en_US'));
     }
 
-    public function testMbFormat()
+    public function testMbFormat(): void
     {
         $this->assertSame('3.3 MB', number_to_size(3_456_789, 1, 'en_US'));
     }
 
-    public function testGbFormat()
+    public function testGbFormat(): void
     {
         $this->assertSame('1.8 GB', number_to_size(1_932_735_283.2, 1, 'en_US'));
     }
 
-    public function testTbFormat()
+    public function testTbFormat(): void
     {
         $this->assertSame('112,283.3 TB', number_to_size(123_456_789_123_456_789, 1, 'en_US'));
     }
 
-    public function testThousands()
+    public function testThousands(): void
     {
         $this->assertSame('123 thousand', number_to_amount('123,000', 0, 'en_US'));
         $this->assertSame('1 thousand', number_to_amount('1000', 0, 'en_US'));
@@ -107,7 +107,7 @@ public function testThousands()
         $this->assertSame('1,000 thousand', number_to_amount('999999', 0, 'en_US'));
     }
 
-    public function testMillions()
+    public function testMillions(): void
     {
         $this->assertSame('123.4 million', number_to_amount('123,400,000', 1, 'en_US'));
         $this->assertSame('1 million', number_to_amount('1,000,000', 1, 'en_US'));
@@ -120,21 +120,21 @@ public function testMillions()
         $this->assertSame('1,000 million', number_to_amount('999,999,999', 1, 'en_US'));
     }
 
-    public function testBillions()
+    public function testBillions(): void
     {
         $this->assertSame('123.46 billion', number_to_amount('123,456,000,000', 2, 'en_US'));
         $this->assertSame('1 billion', number_to_amount('1,000,000,000', 2, 'en_US'));
         $this->assertSame('1,000 billion', number_to_amount('999,999,999,999', 2, 'en_US'));
     }
 
-    public function testTrillions()
+    public function testTrillions(): void
     {
         $this->assertSame('123.457 trillion', number_to_amount('123,456,700,000,000', 3, 'en_US'));
         $this->assertSame('1 trillion', number_to_amount('1,000,000,000,000', 3, 'en_US'));
         $this->assertSame('1,000 trillion', number_to_amount('999,999,999,999,999', 3, 'en_US'));
     }
 
-    public function testQuadrillions()
+    public function testQuadrillions(): void
     {
         $this->assertSame('123.5 quadrillion', number_to_amount('123,456,700,000,000,000', 1, 'en_US'));
         $this->assertSame('1 quadrillion', number_to_amount('1,000,000,000,000,000', 0, 'en_US'));
@@ -142,7 +142,7 @@ public function testQuadrillions()
         $this->assertSame('1,000 quadrillion', number_to_amount('1,000,000,000,000,000,000', 0, 'en_US'));
     }
 
-    public function testCurrencyCurrentLocale()
+    public function testCurrencyCurrentLocale(): void
     {
         $this->assertSame('$1,235', number_to_currency(1234.56, 'USD', 'en_US'));
         $this->assertSame('$1,234.56', number_to_currency(1234.56, 'USD', 'en_US', 2));
@@ -150,7 +150,7 @@ public function testCurrencyCurrentLocale()
         $this->assertSame("1.234,56\u{a0}RSD", number_to_currency(1234.56, 'RSD', 'sr_RS', 2));
     }
 
-    public function testNumbersThatArent()
+    public function testNumbersThatArent(): void
     {
         $this->assertFalse(number_to_size('1232x'));
         $this->assertFalse(number_to_amount('1232x'));
diff --git a/tests/system/Helpers/SecurityHelperTest.php b/tests/system/Helpers/SecurityHelperTest.php
index c7523e3b0081..cb719b1ab2d8 100644
--- a/tests/system/Helpers/SecurityHelperTest.php
+++ b/tests/system/Helpers/SecurityHelperTest.php
@@ -30,27 +30,27 @@ protected function setUp(): void
         helper('security');
     }
 
-    public function testSanitizeFilenameSimpleSuccess()
+    public function testSanitizeFilenameSimpleSuccess(): void
     {
         Services::injectMock('security', new MockSecurity(new App()));
 
         $this->assertSame('hello.doc', sanitize_filename('hello.doc'));
     }
 
-    public function testSanitizeFilenameStripsExtras()
+    public function testSanitizeFilenameStripsExtras(): void
     {
         $filename = './<!--foo -->';
         $this->assertSame('foo ', sanitize_filename($filename));
     }
 
-    public function testStripImageTags()
+    public function testStripImageTags(): void
     {
         $this->assertSame('http://example.com/spacer.gif', strip_image_tags('http://example.com/spacer.gif'));
 
         $this->assertSame('http://example.com/spacer.gif', strip_image_tags('<img src="http://example.com/spacer.gif" alt="Who needs CSS when you have a spacer.gif?" />'));
     }
 
-    public function testEncodePhpTags()
+    public function testEncodePhpTags(): void
     {
         $this->assertSame('&lt;? echo $foo; ?&gt;', encode_php_tags('<? echo $foo; ?>'));
     }
diff --git a/tests/system/Helpers/TextHelperTest.php b/tests/system/Helpers/TextHelperTest.php
index 27f878979282..4d0295e11d46 100755
--- a/tests/system/Helpers/TextHelperTest.php
+++ b/tests/system/Helpers/TextHelperTest.php
@@ -30,7 +30,7 @@ protected function setUp(): void
         helper('text');
     }
 
-    public function testStripSlashes()
+    public function testStripSlashes(): void
     {
         $expected = [
             "Is your name O'reilly?",
@@ -43,7 +43,7 @@ public function testStripSlashes()
         $this->assertSame($expected, strip_slashes($str));
     }
 
-    public function testStripQuotes()
+    public function testStripQuotes(): void
     {
         $strs = [
             '"me oh my!"'    => 'me oh my!',
@@ -55,7 +55,7 @@ public function testStripQuotes()
         }
     }
 
-    public function testQuotesToEntities()
+    public function testQuotesToEntities(): void
     {
         $strs = [
             '"me oh my!"'    => '&quot;me oh my!&quot;',
@@ -67,7 +67,7 @@ public function testQuotesToEntities()
         }
     }
 
-    public function testReduceDoubleSlashes()
+    public function testReduceDoubleSlashes(): void
     {
         $strs = [
             'http://codeigniter.com'      => 'http://codeigniter.com',
@@ -80,7 +80,7 @@ public function testReduceDoubleSlashes()
         }
     }
 
-    public function testReduceMultiples()
+    public function testReduceMultiples(): void
     {
         $strs = [
             'Fred, Bill,, Joe, Jimmy' => 'Fred, Bill, Joe, Jimmy',
@@ -100,7 +100,7 @@ public function testReduceMultiples()
         }
     }
 
-    public function testRandomString()
+    public function testRandomString(): void
     {
         $this->assertSame(16, strlen(random_string('alnum', 16)));
         $this->assertSame(16, strlen(random_string('alpha', 16)));
@@ -119,7 +119,7 @@ public function testRandomString()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6330
      */
-    public function testRandomStringCryptoOddNumber()
+    public function testRandomStringCryptoOddNumber(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage(
@@ -129,7 +129,7 @@ public function testRandomStringCryptoOddNumber()
         random_string('crypto', 9);
     }
 
-    public function testIncrementString()
+    public function testIncrementString(): void
     {
         $this->assertSame('my-test_1', increment_string('my-test'));
         $this->assertSame('my-test-1', increment_string('my-test', '-'));
@@ -142,7 +142,7 @@ public function testIncrementString()
 
     // Functions from text_helper_test.php
 
-    public function testWordLimiter()
+    public function testWordLimiter(): void
     {
         $this->assertSame('Once upon a time,&#8230;', word_limiter($this->_long_string, 4));
         $this->assertSame('Once upon a time,&hellip;', word_limiter($this->_long_string, 4, '&hellip;'));
@@ -151,7 +151,7 @@ public function testWordLimiter()
         $this->assertSame('Once upon a time', word_limiter('Once upon a time', 4, '&hellip;'));
     }
 
-    public function testCharacterLimiter()
+    public function testCharacterLimiter(): void
     {
         $this->assertSame('Once upon a time, a&#8230;', character_limiter($this->_long_string, 20));
         $this->assertSame('Once upon a time, a&hellip;', character_limiter($this->_long_string, 20, '&hellip;'));
@@ -159,7 +159,7 @@ public function testCharacterLimiter()
         $this->assertSame('Short', character_limiter('Short', 5));
     }
 
-    public function testAsciiToEntities()
+    public function testAsciiToEntities(): void
     {
         $strs = [
             'Œ'              => '&#338;',
@@ -174,7 +174,7 @@ public function testAsciiToEntities()
         }
     }
 
-    public function testEntitiesToAscii()
+    public function testEntitiesToAscii(): void
     {
         $strs = [
             '&#338;'                                                                                  => 'Œ',
@@ -189,31 +189,31 @@ public function testEntitiesToAscii()
         }
     }
 
-    public function testEntitiesToAsciiUnsafe()
+    public function testEntitiesToAsciiUnsafe(): void
     {
         $str = '&lt;&gt;';
         $this->assertSame('<>', entities_to_ascii($str, true));
         $this->assertSame('&lt;&gt;', entities_to_ascii($str, false));
     }
 
-    public function testEntitiesToAsciiSmallOrdinals()
+    public function testEntitiesToAsciiSmallOrdinals(): void
     {
         $str = '&#07;';
         $this->assertSame(pack('c', 7), entities_to_ascii($str));
     }
 
-    public function testConvertAccentedCharacters()
+    public function testConvertAccentedCharacters(): void
     {
         $this->assertSame('AAAeEEEIIOOEUUUeY', convert_accented_characters('ÀÂÄÈÊËÎÏÔŒÙÛÜŸ'));
         $this->assertSame('a e i o u n ue', convert_accented_characters('á é í ó ú ñ ü'));
     }
 
-    public function testCensoredWords()
+    public function testCensoredWords(): void
     {
         $this->assertSame('fuck', word_censor('fuck', []));
     }
 
-    public function testCensoredWordsWithReplacement()
+    public function testCensoredWordsWithReplacement(): void
     {
         $censored = [
             'boob',
@@ -238,7 +238,7 @@ public function testCensoredWordsWithReplacement()
         }
     }
 
-    public function testCensoredWordsNonReplacement()
+    public function testCensoredWordsNonReplacement(): void
     {
         $censored = [
             'boob',
@@ -261,13 +261,13 @@ public function testCensoredWordsNonReplacement()
         }
     }
 
-    public function testHighlightCode()
+    public function testHighlightCode(): void
     {
         $expect = "<code><span style=\"color: #000000\">\n<span style=\"color: #0000BB\">&lt;?php&nbsp;var_dump</span><span style=\"color: #007700\">(</span><span style=\"color: #0000BB\">\$this</span><span style=\"color: #007700\">);&nbsp;</span><span style=\"color: #0000BB\">?&gt;&nbsp;</span>\n</span>\n</code>";
         $this->assertSame($expect, highlight_code('<?php var_dump($this); ?>'));
     }
 
-    public function testHighlightPhrase()
+    public function testHighlightPhrase(): void
     {
         $strs = [
             'this is a phrase'        => '<mark>this is</mark> a phrase',
@@ -284,7 +284,7 @@ public function testHighlightPhrase()
         $this->assertSame('<strong>this is</strong> a strong test', highlight_phrase('this is a strong test', 'this is', '<strong>', '</strong>'));
     }
 
-    public function testEllipsize()
+    public function testEllipsize(): void
     {
         $strs = [
             '0' => [
@@ -314,7 +314,7 @@ public function testEllipsize()
         }
     }
 
-    public function testWordWrap()
+    public function testWordWrap(): void
     {
         $string   = 'Here is a simple string of text that will help us demonstrate this function.';
         $expected = "Here is a simple string\nof text that will help us\ndemonstrate this\nfunction.";
@@ -332,7 +332,7 @@ public function testWordWrap()
         $this->assertSame($expected3, word_wrap($string3, 25));
     }
 
-    public function testWordWrapUnwrap()
+    public function testWordWrapUnwrap(): void
     {
         $string   = 'Here is a {unwrap}simple string of text{/unwrap} that will help us demonstrate this function.';
         $expected = "Here is a simple string of text\nthat will help us\ndemonstrate this\nfunction.";
@@ -340,7 +340,7 @@ public function testWordWrapUnwrap()
         $this->assertSame($expected, word_wrap($string, 25));
     }
 
-    public function testWordWrapLongWords()
+    public function testWordWrapLongWords(): void
     {
         // the really really long word will be split
         $string   = 'Here is an unbelievable super-complicated and reallyreallyquiteextraordinarily sophisticated sentence.';
@@ -348,7 +348,7 @@ public function testWordWrapLongWords()
         $this->assertSame($expected, word_wrap($string, 25));
     }
 
-    public function testWordWrapURL()
+    public function testWordWrapURL(): void
     {
         // the really really long word will be split
         $string   = 'Here is an unbelievable super-complicated and http://www.reallyreallyquiteextraordinarily.com sophisticated sentence.';
@@ -356,20 +356,20 @@ public function testWordWrapURL()
         $this->assertSame($expected, word_wrap($string, 25));
     }
 
-    public function testDefaultWordWrapCharlim()
+    public function testDefaultWordWrapCharlim(): void
     {
         $string = 'Here is a longer string of text that will help us demonstrate the default charlim of this function.';
         $this->assertSame(strpos(word_wrap($string), "\n"), 73);
     }
 
-    public function testExcerpt()
+    public function testExcerpt(): void
     {
         $string = $this->_long_string;
         $result = ' Once upon a time, a framework had no tests. It sad  So some nice people began to write tests. The more time that went on, the happier it became. ...';
         $this->assertSame(excerpt($string), $result);
     }
 
-    public function testExcerptRadius()
+    public function testExcerptRadius(): void
     {
         $string = $this->_long_string;
         $phrase = 'began';
@@ -377,7 +377,7 @@ public function testExcerptRadius()
         $this->assertSame(excerpt($string, $phrase, 10), $result);
     }
 
-    public function testAlternator()
+    public function testAlternator(): void
     {
         $phrase = ' scream! ';
         $result = '';
@@ -389,7 +389,7 @@ public function testAlternator()
         $this->assertSame('I scream! you scream! we scream! I scream! ', $result);
     }
 
-    public function testEmptyAlternator()
+    public function testEmptyAlternator(): void
     {
         $phrase = ' scream! ';
         $result = '';
diff --git a/tests/system/Helpers/URLHelper/CurrentUrlTest.php b/tests/system/Helpers/URLHelper/CurrentUrlTest.php
index 204a684aa857..ec639e104594 100644
--- a/tests/system/Helpers/URLHelper/CurrentUrlTest.php
+++ b/tests/system/Helpers/URLHelper/CurrentUrlTest.php
@@ -56,7 +56,7 @@ protected function tearDown(): void
         $_SERVER = [];
     }
 
-    public function testCurrentURLReturnsBasicURL()
+    public function testCurrentURLReturnsBasicURL(): void
     {
         $_SERVER['REQUEST_URI'] = '/public';
         $_SERVER['SCRIPT_NAME'] = '/public/index.php';
@@ -70,7 +70,7 @@ public function testCurrentURLReturnsBasicURL()
         $this->assertSame('http://example.com/public/index.php/', current_url());
     }
 
-    public function testCurrentURLReturnsAllowedHostname()
+    public function testCurrentURLReturnsAllowedHostname(): void
     {
         $_SERVER['HTTP_HOST']   = 'www.example.jp';
         $_SERVER['REQUEST_URI'] = '/public';
@@ -82,7 +82,7 @@ public function testCurrentURLReturnsAllowedHostname()
         $this->assertSame('http://www.example.jp/public/index.php/', current_url());
     }
 
-    public function testCurrentURLReturnsBaseURLIfNotAllowedHostname()
+    public function testCurrentURLReturnsBaseURLIfNotAllowedHostname(): void
     {
         $_SERVER['HTTP_HOST']   = 'invalid.example.org';
         $_SERVER['REQUEST_URI'] = '/public';
@@ -94,7 +94,7 @@ public function testCurrentURLReturnsBaseURLIfNotAllowedHostname()
         $this->assertSame('http://example.com/public/index.php/', current_url());
     }
 
-    public function testCurrentURLReturnsObject()
+    public function testCurrentURLReturnsObject(): void
     {
         // Since we're on a CLI, we must provide our own URI
         $this->config->baseURL = 'http://example.com/public';
@@ -105,7 +105,7 @@ public function testCurrentURLReturnsObject()
         $this->assertSame('http://example.com/public/index.php/', (string) $url);
     }
 
-    public function testCurrentURLEquivalence()
+    public function testCurrentURLEquivalence(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/public';
@@ -120,7 +120,7 @@ public function testCurrentURLEquivalence()
         $this->assertSame(site_url(uri_string()), current_url());
     }
 
-    public function testCurrentURLInSubfolder()
+    public function testCurrentURLInSubfolder(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/foo/public/bar?baz=quip';
@@ -142,7 +142,7 @@ public function testCurrentURLInSubfolder()
         $this->assertSame('http', $uri->getScheme());
     }
 
-    public function testCurrentURLWithPortInSubfolder()
+    public function testCurrentURLWithPortInSubfolder(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['SERVER_PORT'] = '8080';
@@ -167,7 +167,7 @@ public function testCurrentURLWithPortInSubfolder()
         $this->assertSame(8080, $uri->getPort());
     }
 
-    public function testUriString()
+    public function testUriString(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/assets/image.jpg';
@@ -187,7 +187,7 @@ private function setService(string $uri): void
         Services::injectMock('request', $request);
     }
 
-    public function testUriStringNoTrailingSlash()
+    public function testUriStringNoTrailingSlash(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/assets/image.jpg';
@@ -200,7 +200,7 @@ public function testUriStringNoTrailingSlash()
         $this->assertSame('assets/image.jpg', uri_string());
     }
 
-    public function testUriStringEmpty()
+    public function testUriStringEmpty(): void
     {
         $uri = 'http://example.com/';
         $this->setService($uri);
@@ -208,7 +208,7 @@ public function testUriStringEmpty()
         $this->assertSame('', uri_string());
     }
 
-    public function testUriStringSubfolderAbsolute()
+    public function testUriStringSubfolderAbsolute(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/subfolder/assets/image.jpg';
@@ -221,7 +221,7 @@ public function testUriStringSubfolderAbsolute()
         $this->assertSame('subfolder/assets/image.jpg', uri_string());
     }
 
-    public function testUriStringSubfolderRelative()
+    public function testUriStringSubfolderRelative(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/subfolder/assets/image.jpg';
@@ -279,7 +279,7 @@ public function urlIsProvider(): iterable
     /**
      * @dataProvider urlIsProvider
      */
-    public function testUrlIs(string $currentPath, string $testPath, bool $expected)
+    public function testUrlIs(string $currentPath, string $testPath, bool $expected): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/' . $currentPath;
@@ -293,7 +293,7 @@ public function testUrlIs(string $currentPath, string $testPath, bool $expected)
     /**
      * @dataProvider urlIsProvider
      */
-    public function testUrlIsNoIndex(string $currentPath, string $testPath, bool $expected)
+    public function testUrlIsNoIndex(string $currentPath, string $testPath, bool $expected): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/' . $currentPath;
@@ -309,7 +309,7 @@ public function testUrlIsNoIndex(string $currentPath, string $testPath, bool $ex
     /**
      * @dataProvider urlIsProvider
      */
-    public function testUrlIsWithSubfolder(string $currentPath, string $testPath, bool $expected)
+    public function testUrlIsWithSubfolder(string $currentPath, string $testPath, bool $expected): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/' . $currentPath;
diff --git a/tests/system/Helpers/URLHelper/MiscUrlTest.php b/tests/system/Helpers/URLHelper/MiscUrlTest.php
index af3869dcafee..6d4daf8d56c1 100644
--- a/tests/system/Helpers/URLHelper/MiscUrlTest.php
+++ b/tests/system/Helpers/URLHelper/MiscUrlTest.php
@@ -50,7 +50,7 @@ protected function tearDown(): void
         $_SERVER = [];
     }
 
-    public function testPreviousURLUsesSessionFirst()
+    public function testPreviousURLUsesSessionFirst(): void
     {
         $uri1 = 'http://example.com/one?two';
         $uri2 = 'http://example.com/two?foo';
@@ -76,7 +76,7 @@ private function setRequest(string $uri): void
         Services::injectMock('request', $request);
     }
 
-    public function testPreviousURLUsesRefererIfNeeded()
+    public function testPreviousURLUsesRefererIfNeeded(): void
     {
         $uri1 = 'http://example.com/one?two';
 
@@ -92,7 +92,7 @@ public function testPreviousURLUsesRefererIfNeeded()
 
     // Test index_page
 
-    public function testIndexPage()
+    public function testIndexPage(): void
     {
         $uri = 'http://example.com/';
         $this->setRequest($uri);
@@ -100,7 +100,7 @@ public function testIndexPage()
         $this->assertSame('index.php', index_page());
     }
 
-    public function testIndexPageAlt()
+    public function testIndexPageAlt(): void
     {
         $this->config->indexPage = 'banana.php';
 
@@ -163,7 +163,7 @@ public function anchorNormalPatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testAnchor($expected = '', $uri = '', $title = '', $attributes = '')
+    public function testAnchor($expected = '', $uri = '', $title = '', $attributes = ''): void
     {
         $uriString = 'http://example.com/';
         $this->setRequest($uriString);
@@ -228,7 +228,7 @@ public function anchorNoindexPatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testAnchorNoindex($expected = '', $uri = '', $title = '', $attributes = '')
+    public function testAnchorNoindex($expected = '', $uri = '', $title = '', $attributes = ''): void
     {
         $this->config->indexPage = '';
 
@@ -285,7 +285,7 @@ public function anchorSubpagePatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testAnchorTargetted($expected = '', $uri = '', $title = '', $attributes = '')
+    public function testAnchorTargetted($expected = '', $uri = '', $title = '', $attributes = ''): void
     {
         $this->config->indexPage = '';
 
@@ -331,7 +331,7 @@ public function anchorExamplePatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testAnchorExamples($expected = '', $uri = '', $title = '', $attributes = '')
+    public function testAnchorExamples($expected = '', $uri = '', $title = '', $attributes = ''): void
     {
         $uriString = 'http://example.com/';
         $this->setRequest($uriString);
@@ -389,7 +389,7 @@ public function anchorPopupPatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testAnchorPopup($expected = '', $uri = '', $title = '', $attributes = false)
+    public function testAnchorPopup($expected = '', $uri = '', $title = '', $attributes = false): void
     {
         $uriString = 'http://example.com/';
         $this->setRequest($uriString);
@@ -428,7 +428,7 @@ public function mailtoPatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testMailto($expected = '', $email = '', $title = '', $attributes = '')
+    public function testMailto($expected = '', $email = '', $title = '', $attributes = ''): void
     {
         $uriString = 'http://example.com/';
         $this->setRequest($uriString);
@@ -467,7 +467,7 @@ public function safeMailtoPatterns(): iterable
      * @param mixed $title
      * @param mixed $attributes
      */
-    public function testSafeMailto($expected = '', $email = '', $title = '', $attributes = '')
+    public function testSafeMailto($expected = '', $email = '', $title = '', $attributes = ''): void
     {
         $uriString = 'http://example.com/';
         $this->setRequest($uriString);
@@ -475,7 +475,7 @@ public function testSafeMailto($expected = '', $email = '', $title = '', $attrib
         $this->assertSame($expected, safe_mailto($email, $title, $attributes));
     }
 
-    public function testSafeMailtoWithCsp()
+    public function testSafeMailtoWithCsp(): void
     {
         $this->config->CSPEnabled = true;
         Factories::injectMock('config', 'App', $this->config);
@@ -531,7 +531,7 @@ public function autolinkUrls(): iterable
      * @param mixed $in
      * @param mixed $out
      */
-    public function testAutoLinkUrl($in, $out)
+    public function testAutoLinkUrl($in, $out): void
     {
         $this->assertSame($out, auto_link($in, 'url'));
     }
@@ -580,7 +580,7 @@ public function autolinkEmails(): iterable
      * @param mixed $in
      * @param mixed $out
      */
-    public function testAutoLinkEmail($in, $out)
+    public function testAutoLinkEmail($in, $out): void
     {
         $this->assertSame($out, auto_link($in, 'email'));
     }
@@ -629,7 +629,7 @@ public function autolinkBoth(): iterable
      * @param mixed $in
      * @param mixed $out
      */
-    public function testAutolinkBoth($in, $out)
+    public function testAutolinkBoth($in, $out): void
     {
         $this->assertSame($out, auto_link($in));
     }
@@ -678,7 +678,7 @@ public function autolinkPopup(): iterable
      * @param mixed $in
      * @param mixed $out
      */
-    public function testAutoLinkPopup($in, $out)
+    public function testAutoLinkPopup($in, $out): void
     {
         $this->assertSame($out, auto_link($in, 'url', true));
     }
@@ -765,14 +765,14 @@ public function prepUrlProvider(): iterable
     /**
      * @dataProvider prepUrlProvider
      */
-    public function testPrepUrl(string $input, string $expected, bool $secure)
+    public function testPrepUrl(string $input, string $expected, bool $secure): void
     {
         $this->assertSame($expected, prep_url($input, $secure));
     }
 
     // Test url_title
 
-    public function testUrlTitle()
+    public function testUrlTitle(): void
     {
         $words = [
             'foo bar /'       => 'foo-bar',
@@ -785,7 +785,7 @@ public function testUrlTitle()
         }
     }
 
-    public function testUrlTitleExtraDashes()
+    public function testUrlTitleExtraDashes(): void
     {
         $words = [
             '_foo bar_'                 => 'foo_bar',
@@ -800,7 +800,7 @@ public function testUrlTitleExtraDashes()
 
     // Test mb_url_title
 
-    public function testMbUrlTitle()
+    public function testMbUrlTitle(): void
     {
         $words = [
             'foo bar /'       => 'foo-bar',
@@ -814,7 +814,7 @@ public function testMbUrlTitle()
         }
     }
 
-    public function testMbUrlTitleExtraDashes()
+    public function testMbUrlTitleExtraDashes(): void
     {
         $words = [
             '_foo bar_'                 => 'foo_bar',
@@ -831,7 +831,7 @@ public function testMbUrlTitleExtraDashes()
     /**
      * @dataProvider urlToProvider
      */
-    public function testUrlTo(string $expected, string $input, ...$args)
+    public function testUrlTo(string $expected, string $input, ...$args): void
     {
         $_SERVER['HTTP_HOST'] = 'example.com';
 
@@ -847,7 +847,7 @@ public function testUrlTo(string $expected, string $input, ...$args)
     /**
      * @dataProvider urlToMissingRoutesProvider
      */
-    public function testUrlToThrowsOnEmptyOrMissingRoute(string $route)
+    public function testUrlToThrowsOnEmptyOrMissingRoute(string $route): void
     {
         $this->expectException(RouterException::class);
 
@@ -886,7 +886,7 @@ public function urlToMissingRoutesProvider(): iterable
         ];
     }
 
-    public function testUrlToWithSupportedLocaleInRoute()
+    public function testUrlToWithSupportedLocaleInRoute(): void
     {
         Services::createRequest(new App());
         $routes = service('routes');
@@ -905,13 +905,13 @@ public function testUrlToWithSupportedLocaleInRoute()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/7651
      */
-    public function testUrlToMissingArgument()
+    public function testUrlToMissingArgument(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('Missing argument for "([a-zA-Z]+)" in route "([a-zA-Z]+)/login".');
 
         $routes = Services::routes();
-        $routes->group('(:alpha)', static function ($routes) {
+        $routes->group('(:alpha)', static function ($routes): void {
             $routes->match(['get'], 'login', 'Common\LoginController::loginView', ['as' => 'loginURL']);
         });
 
diff --git a/tests/system/Helpers/URLHelper/SiteUrlTest.php b/tests/system/Helpers/URLHelper/SiteUrlTest.php
index 6017f3047790..36fe9882c6d6 100644
--- a/tests/system/Helpers/URLHelper/SiteUrlTest.php
+++ b/tests/system/Helpers/URLHelper/SiteUrlTest.php
@@ -71,7 +71,7 @@ public function testUrls(
         $path,
         $expectedSiteUrl,
         $expectedBaseUrl
-    ) {
+    ): void {
         // Set the config
         $this->config->baseURL                   = $baseURL;
         $this->config->indexPage                 = $indexPage;
@@ -304,7 +304,7 @@ public function configProvider(): iterable
         ];
     }
 
-    public function testSiteURLWithEmptyStringScheme()
+    public function testSiteURLWithEmptyStringScheme(): void
     {
         $this->config->baseURL                   = 'http://example.com/';
         $this->config->indexPage                 = 'index.php';
@@ -326,7 +326,7 @@ public function testSiteURLWithEmptyStringScheme()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/240
      */
-    public function testBaseURLDiscovery()
+    public function testBaseURLDiscovery(): void
     {
         $this->config->baseURL = 'http://example.com/';
 
@@ -342,7 +342,7 @@ public function testBaseURLDiscovery()
         $this->assertSame('http://example.com/profile', base_url('profile'));
     }
 
-    public function testBaseURLService()
+    public function testBaseURLService(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/ci/v4/x/y';
@@ -355,7 +355,7 @@ public function testBaseURLService()
         $this->assertSame('http://example.com/ci/v4/controller/method', base_url('controller/method', null));
     }
 
-    public function testBaseURLWithCLIRequest()
+    public function testBaseURLWithCLIRequest(): void
     {
         unset($_SERVER['HTTP_HOST'], $_SERVER['REQUEST_URI']);
 
@@ -373,7 +373,7 @@ public function testBaseURLWithCLIRequest()
         );
     }
 
-    public function testSiteURLWithAllowedHostname()
+    public function testSiteURLWithAllowedHostname(): void
     {
         $_SERVER['HTTP_HOST']   = 'www.example.jp';
         $_SERVER['REQUEST_URI'] = '/public';
@@ -393,7 +393,7 @@ public function testSiteURLWithAllowedHostname()
         );
     }
 
-    public function testSiteURLWithAltConfig()
+    public function testSiteURLWithAltConfig(): void
     {
         $_SERVER['HTTP_HOST']   = 'www.example.jp';
         $_SERVER['REQUEST_URI'] = '/public';
@@ -415,7 +415,7 @@ public function testSiteURLWithAltConfig()
         );
     }
 
-    public function testBaseURLWithAllowedHostname()
+    public function testBaseURLWithAllowedHostname(): void
     {
         $_SERVER['HTTP_HOST']   = 'www.example.jp';
         $_SERVER['REQUEST_URI'] = '/public';
diff --git a/tests/system/Helpers/XMLHelperTest.php b/tests/system/Helpers/XMLHelperTest.php
index 975415a0ec2f..34d93254a9aa 100644
--- a/tests/system/Helpers/XMLHelperTest.php
+++ b/tests/system/Helpers/XMLHelperTest.php
@@ -27,14 +27,14 @@ protected function setUp(): void
         helper('xml');
     }
 
-    public function testConvert()
+    public function testConvert(): void
     {
         $original = '<p>Here is a so-so paragraph & an entity (&#123;).</p>';
         $expected = '&lt;p&gt;Here is a so&#45;so paragraph &amp; an entity (&#123;).&lt;/p&gt;';
         $this->assertSame($expected, xml_convert($original));
     }
 
-    public function testConvertProtected()
+    public function testConvertProtected(): void
     {
         $original = '<p>Here is a so&so; paragraph & an entity (&#123;).</p>';
         $expected = '&lt;p&gt;Here is a so&so; paragraph &amp; an entity (&#123;).&lt;/p&gt;';
diff --git a/tests/system/HomeTest.php b/tests/system/HomeTest.php
index 2e0323fd631e..d7c132e9736d 100644
--- a/tests/system/HomeTest.php
+++ b/tests/system/HomeTest.php
@@ -24,7 +24,7 @@ final class HomeTest extends CIUnitTestCase
 {
     use FeatureTestTrait;
 
-    public function testPageLoadsSuccessfully()
+    public function testPageLoadsSuccessfully(): void
     {
         $this->withRoutes([
             [
diff --git a/tests/system/Honeypot/HoneypotTest.php b/tests/system/Honeypot/HoneypotTest.php
index b87ce3fe3c48..65b27e3e07d6 100644
--- a/tests/system/Honeypot/HoneypotTest.php
+++ b/tests/system/Honeypot/HoneypotTest.php
@@ -56,7 +56,7 @@ protected function setUp(): void
         $this->response = Services::response();
     }
 
-    public function testAttachHoneypot()
+    public function testAttachHoneypot(): void
     {
         $this->response->setBody('<form></form>');
 
@@ -67,7 +67,7 @@ public function testAttachHoneypot()
         $this->assertStringNotContainsString($this->config->name, $this->response->getBody());
     }
 
-    public function testAttachHoneypotAndContainer()
+    public function testAttachHoneypotAndContainer(): void
     {
         $this->response->setBody('<form></form>');
         $this->honeypot->attachHoneypot($this->response);
@@ -81,7 +81,7 @@ public function testAttachHoneypotAndContainer()
         $this->assertSame($expected, $this->response->getBody());
     }
 
-    public function testAttachHoneypotAndContainerWithCSP()
+    public function testAttachHoneypotAndContainerWithCSP(): void
     {
         $this->resetServices();
 
@@ -100,7 +100,7 @@ public function testAttachHoneypotAndContainerWithCSP()
         $this->assertMatchesRegularExpression($regex, $this->response->getBody());
     }
 
-    public function testHasntContent()
+    public function testHasntContent(): void
     {
         unset($_POST[$this->config->name]);
         $this->request = Services::request();
@@ -108,33 +108,33 @@ public function testHasntContent()
         $this->assertFalse($this->honeypot->hasContent($this->request));
     }
 
-    public function testHasContent()
+    public function testHasContent(): void
     {
         $this->assertTrue($this->honeypot->hasContent($this->request));
     }
 
-    public function testConfigHidden()
+    public function testConfigHidden(): void
     {
         $this->config->hidden = '';
         $this->expectException(HoneypotException::class);
         $this->honeypot = new Honeypot($this->config);
     }
 
-    public function testConfigTemplate()
+    public function testConfigTemplate(): void
     {
         $this->config->template = '';
         $this->expectException(HoneypotException::class);
         $this->honeypot = new Honeypot($this->config);
     }
 
-    public function testConfigName()
+    public function testConfigName(): void
     {
         $this->config->name = '';
         $this->expectException(HoneypotException::class);
         $this->honeypot = new Honeypot($this->config);
     }
 
-    public function testHoneypotFilterBefore()
+    public function testHoneypotFilterBefore(): void
     {
         $config = [
             'aliases' => ['trap' => \CodeIgniter\Filters\Honeypot::class],
@@ -151,7 +151,7 @@ public function testHoneypotFilterBefore()
         $filters->run($uri, 'before');
     }
 
-    public function testHoneypotFilterAfter()
+    public function testHoneypotFilterAfter(): void
     {
         $config = [
             'aliases' => ['trap' => \CodeIgniter\Filters\Honeypot::class],
@@ -169,7 +169,7 @@ public function testHoneypotFilterAfter()
         $this->assertStringContainsString($this->config->name, $this->response->getBody());
     }
 
-    public function testEmptyConfigContainer()
+    public function testEmptyConfigContainer(): void
     {
         $config            = new HoneypotConfig();
         $config->container = '';
@@ -181,7 +181,7 @@ public function testEmptyConfigContainer()
         );
     }
 
-    public function testNoTemplateConfigContainer()
+    public function testNoTemplateConfigContainer(): void
     {
         $config            = new HoneypotConfig();
         $config->container = '<div></div>';
diff --git a/tests/system/I18n/TimeDifferenceTest.php b/tests/system/I18n/TimeDifferenceTest.php
index eb54d398c485..0d88e68cf40f 100644
--- a/tests/system/I18n/TimeDifferenceTest.php
+++ b/tests/system/I18n/TimeDifferenceTest.php
@@ -40,7 +40,7 @@ protected function tearDown(): void
         Locale::setDefault($this->currentLocale);
     }
 
-    public function testDifferenceBasics()
+    public function testDifferenceBasics(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $test    = Time::parse('March 10, 2010', 'America/Chicago');
@@ -74,7 +74,7 @@ public function testDifferenceBasics()
         $this->assertSame($diff / SECOND, $obj->getSeconds(true));
     }
 
-    public function testHumanizeYearsSingle()
+    public function testHumanizeYearsSingle(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
 
@@ -83,7 +83,7 @@ public function testHumanizeYearsSingle()
         $this->assertSame('1 year ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeYearsPlural()
+    public function testHumanizeYearsPlural(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 9, 2014 12:00:00', 'America/Chicago');
@@ -91,7 +91,7 @@ public function testHumanizeYearsPlural()
         $this->assertSame('3 years ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeYearsForward()
+    public function testHumanizeYearsForward(): void
     {
         $current = Time::parse('January 1, 2017', 'America/Chicago');
         $diff    = $current->difference('January 1, 2018 12:00:00', 'America/Chicago');
@@ -99,7 +99,7 @@ public function testHumanizeYearsForward()
         $this->assertSame('in 1 year', $diff->humanize('en'));
     }
 
-    public function testHumanizeMonthsSingle()
+    public function testHumanizeMonthsSingle(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('February 9, 2017', 'America/Chicago');
@@ -107,7 +107,7 @@ public function testHumanizeMonthsSingle()
         $this->assertSame('1 month ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeMonthsPlural()
+    public function testHumanizeMonthsPlural(): void
     {
         $current = Time::parse('March 1, 2017', 'America/Chicago');
         $diff    = $current->difference('January 1, 2017', 'America/Chicago');
@@ -115,7 +115,7 @@ public function testHumanizeMonthsPlural()
         $this->assertSame('2 months ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeMonthsForward()
+    public function testHumanizeMonthsForward(): void
     {
         $current = Time::parse('March 1, 2017', 'America/Chicago');
         $diff    = $current->difference('May 1, 2017', 'America/Chicago');
@@ -123,7 +123,7 @@ public function testHumanizeMonthsForward()
         $this->assertSame('in 1 month', $diff->humanize('en'));
     }
 
-    public function testHumanizeDaysSingle()
+    public function testHumanizeDaysSingle(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 9, 2017', 'America/Chicago');
@@ -131,7 +131,7 @@ public function testHumanizeDaysSingle()
         $this->assertSame('1 day ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeDaysPlural()
+    public function testHumanizeDaysPlural(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 8, 2017', 'America/Chicago');
@@ -139,7 +139,7 @@ public function testHumanizeDaysPlural()
         $this->assertSame('2 days ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeDaysForward()
+    public function testHumanizeDaysForward(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 11, 2017', 'America/Chicago');
@@ -147,7 +147,7 @@ public function testHumanizeDaysForward()
         $this->assertSame('in 1 day', $diff->humanize('en'));
     }
 
-    public function testHumanizeHoursSingle()
+    public function testHumanizeHoursSingle(): void
     {
         $current = Time::parse('March 10, 2017 12:00', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017 11:00', 'America/Chicago');
@@ -155,7 +155,7 @@ public function testHumanizeHoursSingle()
         $this->assertSame('1 hour ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeHoursPlural()
+    public function testHumanizeHoursPlural(): void
     {
         $current = Time::parse('March 10, 2017 12:00', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017 10:00', 'America/Chicago');
@@ -163,7 +163,7 @@ public function testHumanizeHoursPlural()
         $this->assertSame('2 hours ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeHoursForward()
+    public function testHumanizeHoursForward(): void
     {
         $current = Time::parse('March 10, 2017 12:00', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017 13:00', 'America/Chicago');
@@ -171,7 +171,7 @@ public function testHumanizeHoursForward()
         $this->assertSame('in 1 hour', $diff->humanize('en'));
     }
 
-    public function testHumanizeMinutesSingle()
+    public function testHumanizeMinutesSingle(): void
     {
         $current = Time::parse('March 10, 2017 12:30', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017 12:29', 'America/Chicago');
@@ -179,7 +179,7 @@ public function testHumanizeMinutesSingle()
         $this->assertSame('1 minute ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeMinutesPlural()
+    public function testHumanizeMinutesPlural(): void
     {
         $current = Time::parse('March 10, 2017 12:30', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017 12:28', 'America/Chicago');
@@ -187,7 +187,7 @@ public function testHumanizeMinutesPlural()
         $this->assertSame('2 minutes ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeMinutesForward()
+    public function testHumanizeMinutesForward(): void
     {
         $current = Time::parse('March 10, 2017 12:30', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017 12:31', 'America/Chicago');
@@ -195,7 +195,7 @@ public function testHumanizeMinutesForward()
         $this->assertSame('in 1 minute', $diff->humanize('en'));
     }
 
-    public function testHumanizeWeeksSingle()
+    public function testHumanizeWeeksSingle(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 2, 2017', 'America/Chicago');
@@ -203,7 +203,7 @@ public function testHumanizeWeeksSingle()
         $this->assertSame('1 week ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeWeeksPlural()
+    public function testHumanizeWeeksPlural(): void
     {
         $current = Time::parse('March 30, 2017', 'America/Chicago');
         $diff    = $current->difference('March 15, 2017', 'America/Chicago');
@@ -211,7 +211,7 @@ public function testHumanizeWeeksPlural()
         $this->assertSame('2 weeks ago', $diff->humanize('en'));
     }
 
-    public function testHumanizeWeeksForward()
+    public function testHumanizeWeeksForward(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 18, 2017', 'America/Chicago');
@@ -219,7 +219,7 @@ public function testHumanizeWeeksForward()
         $this->assertSame('in 1 week', $diff->humanize('en'));
     }
 
-    public function testHumanizeNoDifference()
+    public function testHumanizeNoDifference(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 10, 2017', 'America/Chicago');
@@ -227,7 +227,7 @@ public function testHumanizeNoDifference()
         $this->assertSame('Just now', $diff->humanize('en'));
     }
 
-    public function testGetterUTC()
+    public function testGetterUTC(): void
     {
         $current = Time::parse('March 10, 2017', 'UTC');
         $diff    = $current->difference('March 18, 2017', 'UTC');
@@ -238,7 +238,7 @@ public function testGetterUTC()
         $this->assertNull($diff->nonsense);
     }
 
-    public function testGetterChicagoTime()
+    public function testGetterChicagoTime(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 18, 2017', 'America/Chicago');
@@ -252,7 +252,7 @@ public function testGetterChicagoTime()
         $this->assertNull($diff->nonsense);
     }
 
-    public function testMagicIssetTrue()
+    public function testMagicIssetTrue(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 18, 2017', 'America/Chicago');
@@ -261,7 +261,7 @@ public function testMagicIssetTrue()
         $this->assertFalse(isset($diff->nonsense));
     }
 
-    public function testMagicIssetFalse()
+    public function testMagicIssetFalse(): void
     {
         $current = Time::parse('March 10, 2017', 'America/Chicago');
         $diff    = $current->difference('March 18, 2017', 'America/Chicago');
diff --git a/tests/system/I18n/TimeLegacyTest.php b/tests/system/I18n/TimeLegacyTest.php
index 281970a8aa9d..f9d081709a7b 100644
--- a/tests/system/I18n/TimeLegacyTest.php
+++ b/tests/system/I18n/TimeLegacyTest.php
@@ -52,7 +52,7 @@ protected function tearDown(): void
         TimeLegacy::setTestNow();
     }
 
-    public function testNewTimeNow()
+    public function testNewTimeNow(): void
     {
         $formatter = new IntlDateFormatter(
             'en_US',
@@ -67,7 +67,7 @@ public function testNewTimeNow()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testTimeWithTimezone()
+    public function testTimeWithTimezone(): void
     {
         $formatter = new IntlDateFormatter(
             'en_US',
@@ -83,7 +83,7 @@ public function testTimeWithTimezone()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testTimeWithTimezoneAndLocale()
+    public function testTimeWithTimezoneAndLocale(): void
     {
         $formatter = new IntlDateFormatter(
             'fr_FR',
@@ -99,7 +99,7 @@ public function testTimeWithTimezoneAndLocale()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testTimeWithDateTimeZone()
+    public function testTimeWithDateTimeZone(): void
     {
         $formatter = new IntlDateFormatter(
             'fr_FR',
@@ -115,7 +115,7 @@ public function testTimeWithDateTimeZone()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testToDateTime()
+    public function testToDateTime(): void
     {
         $time = new TimeLegacy();
 
@@ -124,7 +124,7 @@ public function testToDateTime()
         $this->assertInstanceOf(DateTime::class, $obj);
     }
 
-    public function testNow()
+    public function testNow(): void
     {
         $time  = TimeLegacy::now();
         $time1 = new DateTime();
@@ -133,7 +133,7 @@ public function testNow()
         $this->assertSame($time->getTimestamp(), $time1->getTimestamp());
     }
 
-    public function testParse()
+    public function testParse(): void
     {
         $time  = TimeLegacy::parse('next Tuesday', 'America/Chicago');
         $time1 = new DateTime('now', new DateTimeZone('America/Chicago'));
@@ -142,14 +142,14 @@ public function testParse()
         $this->assertSame($time->getTimestamp(), $time1->getTimestamp());
     }
 
-    public function testToDateTimeString()
+    public function testToDateTimeString(): void
     {
         $time = TimeLegacy::parse('2017-01-12 00:00', 'America/Chicago');
 
         $this->assertSame('2017-01-12 00:00:00', $time->toDateTimeString());
     }
 
-    public function testToDateTimeStringWithTimeZone()
+    public function testToDateTimeStringWithTimeZone(): void
     {
         $time = TimeLegacy::parse('2017-01-12 00:00', 'Europe/London');
 
@@ -158,70 +158,70 @@ public function testToDateTimeStringWithTimeZone()
         $this->assertSame($expects->format('Y-m-d H:i:s'), $time->toDateTimeString());
     }
 
-    public function testToday()
+    public function testToday(): void
     {
         $time = TimeLegacy::today();
 
         $this->assertSame(date('Y-m-d 00:00:00'), $time->toDateTimeString());
     }
 
-    public function testTodayLocalized()
+    public function testTodayLocalized(): void
     {
         $time = TimeLegacy::today('Europe/London');
 
         $this->assertSame(date('Y-m-d 00:00:00'), $time->toDateTimeString());
     }
 
-    public function testYesterday()
+    public function testYesterday(): void
     {
         $time = TimeLegacy::yesterday();
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('-1 day')), $time->toDateTimeString());
     }
 
-    public function testTomorrow()
+    public function testTomorrow(): void
     {
         $time = TimeLegacy::tomorrow();
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('+1 day')), $time->toDateTimeString());
     }
 
-    public function testCreateFromDate()
+    public function testCreateFromDate(): void
     {
         $time = TimeLegacy::createFromDate(2017, 03, 05, 'America/Chicago');
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('2017-03-05 00:00:00')), $time->toDateTimeString());
     }
 
-    public function testCreateFromDateLocalized()
+    public function testCreateFromDateLocalized(): void
     {
         $time = TimeLegacy::createFromDate(2017, 03, 05, 'Europe/London');
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('2017-03-05 00:00:00')), $time->toDateTimeString());
     }
 
-    public function testCreateFromTime()
+    public function testCreateFromTime(): void
     {
         $time = TimeLegacy::createFromTime(10, 03, 05, 'America/Chicago');
 
         $this->assertSame(date('Y-m-d 10:03:05'), $time->toDateTimeString());
     }
 
-    public function testCreateFromTimeEvening()
+    public function testCreateFromTimeEvening(): void
     {
         $time = TimeLegacy::createFromTime(20, 03, 05, 'America/Chicago');
 
         $this->assertSame(date('Y-m-d 20:03:05'), $time->toDateTimeString());
     }
 
-    public function testCreateFromTimeLocalized()
+    public function testCreateFromTimeLocalized(): void
     {
         $time = TimeLegacy::createFromTime(10, 03, 05, 'Europe/London');
 
         $this->assertCloseEnoughString(date('Y-m-d 10:03:05'), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormat()
+    public function testCreateFromFormat(): void
     {
         $now = new DateTime('now');
 
@@ -232,14 +232,14 @@ public function testCreateFromFormat()
         TimeLegacy::setTestNow();
     }
 
-    public function testCreateFromFormatWithTimezoneString()
+    public function testCreateFromFormatWithTimezoneString(): void
     {
         $time = TimeLegacy::createFromFormat('F j, Y', 'January 15, 2017', 'Europe/London');
 
         $this->assertCloseEnoughString(date('2017-01-15 H:i:s'), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormatWithTimezoneObject()
+    public function testCreateFromFormatWithTimezoneObject(): void
     {
         $tz = new DateTimeZone('Europe/London');
 
@@ -248,7 +248,7 @@ public function testCreateFromFormatWithTimezoneObject()
         $this->assertCloseEnoughString(date('2017-01-15 H:i:s'), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormatWithInvalidFormat()
+    public function testCreateFromFormatWithInvalidFormat(): void
     {
         $format = 'foobar';
 
@@ -258,7 +258,7 @@ public function testCreateFromFormatWithInvalidFormat()
         TimeLegacy::createFromFormat($format, 'America/Chicago');
     }
 
-    public function testCreateFromTimestamp()
+    public function testCreateFromTimestamp(): void
     {
         // Set the timezone temporarily to UTC to make sure the test timestamp is correct
         $tz = date_default_timezone_get();
@@ -273,7 +273,7 @@ public function testCreateFromTimestamp()
         $this->assertSame(date('2017-03-18 00:00:00'), $time->toDateTimeString());
     }
 
-    public function testCreateFromTimestampWithTimezone()
+    public function testCreateFromTimestampWithTimezone(): void
     {
         // Set the timezone temporarily to UTC to make sure the test timestamp is correct
         $tz = date_default_timezone_get();
@@ -288,7 +288,7 @@ public function testCreateFromTimestampWithTimezone()
         $this->assertSame(date('2017-03-18 07:00:00'), $time->toDateTimeString());
     }
 
-    public function testTestNow()
+    public function testTestNow(): void
     {
         $this->assertFalse(TimeLegacy::hasTestNow());
         $this->assertCloseEnoughString(date('Y-m-d H:i:s', time()), TimeLegacy::now()->toDateTimeString());
@@ -303,21 +303,21 @@ public function testTestNow()
         $this->assertCloseEnoughString(date('Y-m-d H:i:s', time()), TimeLegacy::now()->toDateTimeString());
     }
 
-    public function testMagicIssetTrue()
+    public function testMagicIssetTrue(): void
     {
         $time = TimeLegacy::parse('January 1, 2016');
 
         $this->assertTrue(isset($time->year));
     }
 
-    public function testMagicIssetFalse()
+    public function testMagicIssetFalse(): void
     {
         $time = TimeLegacy::parse('January 1, 2016');
 
         $this->assertFalse(isset($time->foobar));
     }
 
-    public function testGetYear()
+    public function testGetYear(): void
     {
         $time  = TimeLegacy::parse('January 1, 2016');
         $time2 = TimeLegacy::parse('December 31, 2019');
@@ -326,70 +326,70 @@ public function testGetYear()
         $this->assertSame('2019', $time2->year);
     }
 
-    public function testGetMonth()
+    public function testGetMonth(): void
     {
         $time = TimeLegacy::parse('August 1, 2016');
 
         $this->assertSame('8', $time->month);
     }
 
-    public function testGetDay()
+    public function testGetDay(): void
     {
         $time = TimeLegacy::parse('August 12, 2016');
 
         $this->assertSame('12', $time->day);
     }
 
-    public function testGetHour()
+    public function testGetHour(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15pm');
 
         $this->assertSame('16', $time->hour);
     }
 
-    public function testGetMinute()
+    public function testGetMinute(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15pm');
 
         $this->assertSame('15', $time->minute);
     }
 
-    public function testGetSecond()
+    public function testGetSecond(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('23', $time->second);
     }
 
-    public function testGetDayOfWeek()
+    public function testGetDayOfWeek(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('6', $time->dayOfWeek);
     }
 
-    public function testGetDayOfYear()
+    public function testGetDayOfYear(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('225', $time->dayOfYear);
     }
 
-    public function testGetWeekOfMonth()
+    public function testGetWeekOfMonth(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('2', $time->weekOfMonth);
     }
 
-    public function testGetWeekOfYear()
+    public function testGetWeekOfYear(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('33', $time->weekOfYear);
     }
 
-    public function testGetTimestamp()
+    public function testGetTimestamp(): void
     {
         $time     = TimeLegacy::parse('August 12, 2016 4:15:23pm');
         $expected = strtotime('August 12, 2016 4:15:23pm');
@@ -397,7 +397,7 @@ public function testGetTimestamp()
         $this->assertSame($expected, $time->timestamp);
     }
 
-    public function testGetAge()
+    public function testGetAge(): void
     {
         $time = TimeLegacy::parse('5 years ago');
 
@@ -405,14 +405,14 @@ public function testGetAge()
         $this->assertSame(5, $time->age);
     }
 
-    public function testAgeNow()
+    public function testAgeNow(): void
     {
         $time = new TimeLegacy();
 
         $this->assertSame(0, $time->getAge());
     }
 
-    public function testAgeFuture()
+    public function testAgeFuture(): void
     {
         TimeLegacy::setTestNow('June 20, 2022', 'America/Chicago');
         $time = TimeLegacy::parse('August 12, 2116 4:15:23pm');
@@ -420,7 +420,7 @@ public function testAgeFuture()
         $this->assertSame(0, $time->getAge());
     }
 
-    public function testGetAgeSameDayOfBirthday()
+    public function testGetAgeSameDayOfBirthday(): void
     {
         TimeLegacy::setTestNow('December 31, 2022', 'America/Chicago');
         $time = TimeLegacy::parse('December 31, 2020');
@@ -428,7 +428,7 @@ public function testGetAgeSameDayOfBirthday()
         $this->assertSame(2, $time->getAge());
     }
 
-    public function testGetAgeNextDayOfBirthday()
+    public function testGetAgeNextDayOfBirthday(): void
     {
         TimeLegacy::setTestNow('January 1, 2022', 'America/Chicago');
         $time = TimeLegacy::parse('December 31, 2020');
@@ -436,7 +436,7 @@ public function testGetAgeNextDayOfBirthday()
         $this->assertSame(1, $time->getAge());
     }
 
-    public function testGetAgeBeforeDayOfBirthday()
+    public function testGetAgeBeforeDayOfBirthday(): void
     {
         TimeLegacy::setTestNow('December 30, 2021', 'America/Chicago');
         $time = TimeLegacy::parse('December 31, 2020');
@@ -444,14 +444,14 @@ public function testGetAgeBeforeDayOfBirthday()
         $this->assertSame(0, $time->getAge());
     }
 
-    public function testGetQuarter()
+    public function testGetQuarter(): void
     {
         $time = TimeLegacy::parse('April 15, 2015');
 
         $this->assertSame('2', $time->quarter);
     }
 
-    public function testGetDST()
+    public function testGetDST(): void
     {
         // America/Chicago. DST from early March -> early Nov
         $time = TimeLegacy::createFromDate(2012, 1, 1, 'America/Chicago');
@@ -461,7 +461,7 @@ public function testGetDST()
         $this->assertTrue($time->dst);
     }
 
-    public function testGetDSTUnobserved()
+    public function testGetDSTUnobserved(): void
     {
         // Asia/Shanghai. DST not observed
         $tz   = new DateTimeZone('Asia/Shanghai');
@@ -470,32 +470,32 @@ public function testGetDSTUnobserved()
         $this->assertFalse($time->dst);
     }
 
-    public function testGetLocal()
+    public function testGetLocal(): void
     {
         $this->assertTrue(TimeLegacy::now()->local);
         $this->assertFalse(TimeLegacy::now('Europe/London')->local);
     }
 
-    public function testGetUtc()
+    public function testGetUtc(): void
     {
         $this->assertFalse(TimeLegacy::now('America/Chicago')->utc);
         $this->assertTrue(TimeLegacy::now('UTC')->utc);
     }
 
-    public function testGetTimezone()
+    public function testGetTimezone(): void
     {
         $instance = TimeLegacy::now()->getTimezone();
 
         $this->assertInstanceOf(DateTimeZone::class, $instance);
     }
 
-    public function testGetTimezonename()
+    public function testGetTimezonename(): void
     {
         $this->assertSame('America/Chicago', TimeLegacy::now('America/Chicago')->getTimezoneName());
         $this->assertSame('Europe/London', TimeLegacy::now('Europe/London')->timezoneName);
     }
 
-    public function testSetYear()
+    public function testSetYear(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setYear(2015);
@@ -505,7 +505,7 @@ public function testSetYear()
         $this->assertSame('2015-05-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMonthNumber()
+    public function testSetMonthNumber(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setMonth(4);
@@ -515,7 +515,7 @@ public function testSetMonthNumber()
         $this->assertSame('2017-04-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMonthLongName()
+    public function testSetMonthLongName(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setMonth('April');
@@ -525,7 +525,7 @@ public function testSetMonthLongName()
         $this->assertSame('2017-04-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMonthShortName()
+    public function testSetMonthShortName(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setMonth('Feb');
@@ -535,7 +535,7 @@ public function testSetMonthShortName()
         $this->assertSame('2017-02-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetDay()
+    public function testSetDay(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setDay(15);
@@ -545,7 +545,7 @@ public function testSetDay()
         $this->assertSame('2017-05-15 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetDayOverMaxInCurrentMonth()
+    public function testSetDayOverMaxInCurrentMonth(): void
     {
         $this->expectException(I18nException::class);
 
@@ -553,7 +553,7 @@ public function testSetDayOverMaxInCurrentMonth()
         $time->setDay(29);
     }
 
-    public function testSetDayNotOverMaxInCurrentMonth()
+    public function testSetDayNotOverMaxInCurrentMonth(): void
     {
         $time  = TimeLegacy::parse('Feb 02, 2012');
         $time2 = $time->setDay(29);
@@ -563,7 +563,7 @@ public function testSetDayNotOverMaxInCurrentMonth()
         $this->assertSame('2012-02-29 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetHour()
+    public function testSetHour(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setHour(15);
@@ -573,7 +573,7 @@ public function testSetHour()
         $this->assertSame('2017-05-10 15:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMinute()
+    public function testSetMinute(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setMinute(30);
@@ -583,7 +583,7 @@ public function testSetMinute()
         $this->assertSame('2017-05-10 00:30:00', $time2->toDateTimeString());
     }
 
-    public function testSetSecond()
+    public function testSetSecond(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017');
         $time2 = $time->setSecond(20);
@@ -593,7 +593,7 @@ public function testSetSecond()
         $this->assertSame('2017-05-10 00:00:20', $time2->toDateTimeString());
     }
 
-    public function testSetMonthTooSmall()
+    public function testSetMonthTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -601,7 +601,7 @@ public function testSetMonthTooSmall()
         $time->setMonth(-5);
     }
 
-    public function testSetMonthTooBig()
+    public function testSetMonthTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -609,7 +609,7 @@ public function testSetMonthTooBig()
         $time->setMonth(30);
     }
 
-    public function testSetDayTooSmall()
+    public function testSetDayTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -617,7 +617,7 @@ public function testSetDayTooSmall()
         $time->setDay(-5);
     }
 
-    public function testSetDayTooBig()
+    public function testSetDayTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -625,7 +625,7 @@ public function testSetDayTooBig()
         $time->setDay(80);
     }
 
-    public function testSetHourTooSmall()
+    public function testSetHourTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -633,7 +633,7 @@ public function testSetHourTooSmall()
         $time->setHour(-5);
     }
 
-    public function testSetHourTooBig()
+    public function testSetHourTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -641,7 +641,7 @@ public function testSetHourTooBig()
         $time->setHour(80);
     }
 
-    public function testSetMinuteTooSmall()
+    public function testSetMinuteTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -649,7 +649,7 @@ public function testSetMinuteTooSmall()
         $time->setMinute(-5);
     }
 
-    public function testSetMinuteTooBig()
+    public function testSetMinuteTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -657,7 +657,7 @@ public function testSetMinuteTooBig()
         $time->setMinute(80);
     }
 
-    public function testSetSecondTooSmall()
+    public function testSetSecondTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -665,7 +665,7 @@ public function testSetSecondTooSmall()
         $time->setSecond(-5);
     }
 
-    public function testSetSecondTooBig()
+    public function testSetSecondTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -673,7 +673,7 @@ public function testSetSecondTooBig()
         $time->setSecond(80);
     }
 
-    public function testSetTimezone()
+    public function testSetTimezone(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017', 'America/Chicago');
         $time2 = $time->setTimezone('Europe/London');
@@ -684,7 +684,7 @@ public function testSetTimezone()
         $this->assertSame('Europe/London', $time2->getTimezoneName());
     }
 
-    public function testSetTimestamp()
+    public function testSetTimestamp(): void
     {
         $time  = TimeLegacy::parse('May 10, 2017', 'America/Chicago');
         $stamp = strtotime('April 1, 2017');
@@ -695,19 +695,19 @@ public function testSetTimestamp()
         $this->assertSame('2017-04-01 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testToDateString()
+    public function testToDateString(): void
     {
         $time = TimeLegacy::parse('May 10, 2017', 'America/Chicago');
         $this->assertSame('2017-05-10', $time->toDateString());
     }
 
-    public function testToFormattedDateString()
+    public function testToFormattedDateString(): void
     {
         $time = TimeLegacy::parse('2017-05-10', 'America/Chicago');
         $this->assertSame('May 10, 2017', $time->toFormattedDateString());
     }
 
-    public function testToTimeString()
+    public function testToTimeString(): void
     {
         $time = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $this->assertSame('13:20:33', $time->toTimeString());
@@ -715,7 +715,7 @@ public function testToTimeString()
 
     // Add/Subtract
 
-    public function testCanAddSeconds()
+    public function testCanAddSeconds(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addSeconds(10);
@@ -723,7 +723,7 @@ public function testCanAddSeconds()
         $this->assertSame('2017-01-10 13:20:43', $newTime->toDateTimeString());
     }
 
-    public function testCanAddMinutes()
+    public function testCanAddMinutes(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addMinutes(10);
@@ -731,7 +731,7 @@ public function testCanAddMinutes()
         $this->assertSame('2017-01-10 13:30:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddHours()
+    public function testCanAddHours(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addHours(3);
@@ -739,7 +739,7 @@ public function testCanAddHours()
         $this->assertSame('2017-01-10 16:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddDays()
+    public function testCanAddDays(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addDays(3);
@@ -747,7 +747,7 @@ public function testCanAddDays()
         $this->assertSame('2017-01-13 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddMonths()
+    public function testCanAddMonths(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addMonths(3);
@@ -755,7 +755,7 @@ public function testCanAddMonths()
         $this->assertSame('2017-04-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddMonthsOverYearBoundary()
+    public function testCanAddMonthsOverYearBoundary(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addMonths(13);
@@ -763,7 +763,7 @@ public function testCanAddMonthsOverYearBoundary()
         $this->assertSame('2018-02-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddYears()
+    public function testCanAddYears(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addYears(3);
@@ -771,7 +771,7 @@ public function testCanAddYears()
         $this->assertSame('2020-01-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractSeconds()
+    public function testCanSubtractSeconds(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subSeconds(10);
@@ -779,7 +779,7 @@ public function testCanSubtractSeconds()
         $this->assertSame('2017-01-10 13:20:23', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractMinutes()
+    public function testCanSubtractMinutes(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subMinutes(10);
@@ -787,7 +787,7 @@ public function testCanSubtractMinutes()
         $this->assertSame('2017-01-10 13:10:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractHours()
+    public function testCanSubtractHours(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subHours(3);
@@ -795,7 +795,7 @@ public function testCanSubtractHours()
         $this->assertSame('2017-01-10 10:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractDays()
+    public function testCanSubtractDays(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subDays(3);
@@ -803,7 +803,7 @@ public function testCanSubtractDays()
         $this->assertSame('2017-01-07 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractMonths()
+    public function testCanSubtractMonths(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subMonths(3);
@@ -811,7 +811,7 @@ public function testCanSubtractMonths()
         $this->assertSame('2016-10-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractYears()
+    public function testCanSubtractYears(): void
     {
         $time    = TimeLegacy::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subYears(3);
@@ -821,7 +821,7 @@ public function testCanSubtractYears()
 
     // Comparison
 
-    public function testEqualWithDifferent()
+    public function testEqualWithDifferent(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = TimeLegacy::parse('January 11, 2017 03:50:00', 'Europe/London');
@@ -829,7 +829,7 @@ public function testEqualWithDifferent()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithSame()
+    public function testEqualWithSame(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
@@ -837,7 +837,7 @@ public function testEqualWithSame()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithDateTime()
+    public function testEqualWithDateTime(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = new DateTime('January 11, 2017 03:50:00', new DateTimeZone('Europe/London'));
@@ -845,7 +845,7 @@ public function testEqualWithDateTime()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithSameDateTime()
+    public function testEqualWithSameDateTime(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = new DateTime('January 10, 2017 21:50:00', new DateTimeZone('America/Chicago'));
@@ -853,21 +853,21 @@ public function testEqualWithSameDateTime()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithString()
+    public function testEqualWithString(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertTrue($time1->equals('January 11, 2017 03:50:00', 'Europe/London'));
     }
 
-    public function testEqualWithStringAndNotimezone()
+    public function testEqualWithStringAndNotimezone(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertTrue($time1->equals('January 10, 2017 21:50:00'));
     }
 
-    public function testSameSuccess()
+    public function testSameSuccess(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
@@ -875,7 +875,7 @@ public function testSameSuccess()
         $this->assertTrue($time1->sameAs($time2));
     }
 
-    public function testSameFailure()
+    public function testSameFailure(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = TimeLegacy::parse('January 11, 2017 03:50:00', 'Europe/London');
@@ -883,21 +883,21 @@ public function testSameFailure()
         $this->assertFalse($time1->sameAs($time2));
     }
 
-    public function testSameSuccessAsString()
+    public function testSameSuccessAsString(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertTrue($time1->sameAs('January 10, 2017 21:50:00', 'America/Chicago'));
     }
 
-    public function testSameFailAsString()
+    public function testSameFailAsString(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertFalse($time1->sameAs('January 11, 2017 03:50:00', 'Europe/London'));
     }
 
-    public function testBefore()
+    public function testBefore(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = TimeLegacy::parse('January 11, 2017 03:50:00', 'America/Chicago');
@@ -906,7 +906,7 @@ public function testBefore()
         $this->assertFalse($time2->isBefore($time1));
     }
 
-    public function testAfter()
+    public function testAfter(): void
     {
         $time1 = TimeLegacy::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = TimeLegacy::parse('January 11, 2017 03:50:00', 'America/Chicago');
@@ -915,7 +915,7 @@ public function testAfter()
         $this->assertTrue($time2->isAfter($time1));
     }
 
-    public function testHumanizeYearsSingle()
+    public function testHumanizeYearsSingle(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 9, 2016 12:00:00', 'America/Chicago');
@@ -923,7 +923,7 @@ public function testHumanizeYearsSingle()
         $this->assertSame('1 year ago', $time->humanize());
     }
 
-    public function testHumanizeYearsPlural()
+    public function testHumanizeYearsPlural(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 9, 2014 12:00:00', 'America/Chicago');
@@ -931,7 +931,7 @@ public function testHumanizeYearsPlural()
         $this->assertSame('3 years ago', $time->humanize());
     }
 
-    public function testHumanizeYearsForward()
+    public function testHumanizeYearsForward(): void
     {
         TimeLegacy::setTestNow('January 1, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('January 1, 2018 12:00:00', 'America/Chicago');
@@ -939,7 +939,7 @@ public function testHumanizeYearsForward()
         $this->assertSame('in 1 year', $time->humanize());
     }
 
-    public function testHumanizeMonthsSingle()
+    public function testHumanizeMonthsSingle(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('February 9, 2017', 'America/Chicago');
@@ -947,7 +947,7 @@ public function testHumanizeMonthsSingle()
         $this->assertSame('1 month ago', $time->humanize());
     }
 
-    public function testHumanizeMonthsPlural()
+    public function testHumanizeMonthsPlural(): void
     {
         TimeLegacy::setTestNow('March 1, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('January 1, 2017', 'America/Chicago');
@@ -955,7 +955,7 @@ public function testHumanizeMonthsPlural()
         $this->assertSame('2 months ago', $time->humanize());
     }
 
-    public function testHumanizeMonthsForward()
+    public function testHumanizeMonthsForward(): void
     {
         TimeLegacy::setTestNow('March 1, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('April 1, 2017', 'America/Chicago');
@@ -963,7 +963,7 @@ public function testHumanizeMonthsForward()
         $this->assertSame('in 1 month', $time->humanize());
     }
 
-    public function testHumanizeDaysSingle()
+    public function testHumanizeDaysSingle(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 8, 2017', 'America/Chicago');
@@ -971,7 +971,7 @@ public function testHumanizeDaysSingle()
         $this->assertSame('2 days ago', $time->humanize());
     }
 
-    public function testHumanizeDaysPlural()
+    public function testHumanizeDaysPlural(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 8, 2017', 'America/Chicago');
@@ -979,7 +979,7 @@ public function testHumanizeDaysPlural()
         $this->assertSame('2 days ago', $time->humanize());
     }
 
-    public function testHumanizeDaysForward()
+    public function testHumanizeDaysForward(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 12, 2017', 'America/Chicago');
@@ -987,7 +987,7 @@ public function testHumanizeDaysForward()
         $this->assertSame('in 2 days', $time->humanize());
     }
 
-    public function testHumanizeDaysTomorrow()
+    public function testHumanizeDaysTomorrow(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 11, 2017', 'America/Chicago');
@@ -995,7 +995,7 @@ public function testHumanizeDaysTomorrow()
         $this->assertSame('Tomorrow', $time->humanize());
     }
 
-    public function testHumanizeDaysYesterday()
+    public function testHumanizeDaysYesterday(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 9, 2017', 'America/Chicago');
@@ -1003,7 +1003,7 @@ public function testHumanizeDaysYesterday()
         $this->assertSame('Yesterday', $time->humanize());
     }
 
-    public function testHumanizeHoursAsTime()
+    public function testHumanizeHoursAsTime(): void
     {
         TimeLegacy::setTestNow('March 10, 2017 12:00', 'America/Chicago');
         $time = TimeLegacy::parse('March 10, 2017 14:00', 'America/Chicago');
@@ -1011,7 +1011,7 @@ public function testHumanizeHoursAsTime()
         $this->assertSame('in 2 hours', $time->humanize());
     }
 
-    public function testHumanizeHoursAWhileAgo()
+    public function testHumanizeHoursAWhileAgo(): void
     {
         TimeLegacy::setTestNow('March 10, 2017 12:00', 'America/Chicago');
         $time = TimeLegacy::parse('March 10, 2017 8:00', 'America/Chicago');
@@ -1019,7 +1019,7 @@ public function testHumanizeHoursAWhileAgo()
         $this->assertSame('4 hours ago', $time->humanize());
     }
 
-    public function testHumanizeMinutesSingle()
+    public function testHumanizeMinutesSingle(): void
     {
         TimeLegacy::setTestNow('March 10, 2017 12:30', 'America/Chicago');
         $time = TimeLegacy::parse('March 10, 2017 12:29', 'America/Chicago');
@@ -1027,7 +1027,7 @@ public function testHumanizeMinutesSingle()
         $this->assertSame('1 minute ago', $time->humanize());
     }
 
-    public function testHumanizeMinutesPlural()
+    public function testHumanizeMinutesPlural(): void
     {
         TimeLegacy::setTestNow('March 10, 2017 12:30', 'America/Chicago');
         $time = TimeLegacy::parse('March 10, 2017 12:28', 'America/Chicago');
@@ -1035,7 +1035,7 @@ public function testHumanizeMinutesPlural()
         $this->assertSame('2 minutes ago', $time->humanize());
     }
 
-    public function testHumanizeMinutesForward()
+    public function testHumanizeMinutesForward(): void
     {
         TimeLegacy::setTestNow('March 10, 2017 12:30', 'America/Chicago');
         $time = TimeLegacy::parse('March 10, 2017 12:31', 'America/Chicago');
@@ -1043,7 +1043,7 @@ public function testHumanizeMinutesForward()
         $this->assertSame('in 1 minute', $time->humanize());
     }
 
-    public function testHumanizeWeeksSingle()
+    public function testHumanizeWeeksSingle(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 2, 2017', 'America/Chicago');
@@ -1051,7 +1051,7 @@ public function testHumanizeWeeksSingle()
         $this->assertSame('1 week ago', $time->humanize());
     }
 
-    public function testHumanizeWeeksPlural()
+    public function testHumanizeWeeksPlural(): void
     {
         TimeLegacy::setTestNow('March 30, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 15, 2017', 'America/Chicago');
@@ -1059,7 +1059,7 @@ public function testHumanizeWeeksPlural()
         $this->assertSame('2 weeks ago', $time->humanize());
     }
 
-    public function testHumanizeWeeksForward()
+    public function testHumanizeWeeksForward(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 18, 2017', 'America/Chicago');
@@ -1067,7 +1067,7 @@ public function testHumanizeWeeksForward()
         $this->assertSame('in 2 weeks', $time->humanize());
     }
 
-    public function testHumanizeNow()
+    public function testHumanizeNow(): void
     {
         TimeLegacy::setTestNow('March 10, 2017', 'America/Chicago');
         $time = TimeLegacy::parse('March 10, 2017', 'America/Chicago');
@@ -1078,7 +1078,7 @@ public function testHumanizeNow()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4708
      */
-    public function testHumanizeWithArLocale()
+    public function testHumanizeWithArLocale(): void
     {
         $this->resetServices();
 
@@ -1100,7 +1100,7 @@ public function testHumanizeWithArLocale()
         Locale::setDefault($currentLocale);
     }
 
-    public function testSetTimezoneDate()
+    public function testSetTimezoneDate(): void
     {
         $time  = TimeLegacy::parse('13 May 2020 10:00', 'GMT');
         $time2 = $time->setTimezone('GMT+8');
@@ -1108,7 +1108,7 @@ public function testSetTimezoneDate()
         $this->assertSame('2020-05-13 18:00:00', $time2->toDateTimeString());
     }
 
-    public function testCreateFromInstance()
+    public function testCreateFromInstance(): void
     {
         $datetime = new DateTime();
         $time     = TimeLegacy::createFromInstance($datetime);
@@ -1116,7 +1116,7 @@ public function testCreateFromInstance()
         $this->assertTrue($time->sameAs($datetime));
     }
 
-    public function testGetter()
+    public function testGetter(): void
     {
         $time = TimeLegacy::parse('August 12, 2016 4:15:23pm');
 
@@ -1135,7 +1135,7 @@ public function testGetter()
     //        $this->assertNotSame($time1, $time2);
     //    }
 
-    public function testSetTestNowWithFaLocale()
+    public function testSetTestNowWithFaLocale(): void
     {
         Locale::setDefault('fa');
 
@@ -1149,7 +1149,7 @@ public function testSetTestNowWithFaLocale()
     /**
      * @dataProvider provideLocales
      */
-    public function testToStringDoesNotDependOnLocale(string $locale)
+    public function testToStringDoesNotDependOnLocale(string $locale): void
     {
         Locale::setDefault($locale);
 
@@ -1168,7 +1168,7 @@ public function provideLocales(): iterable
         ];
     }
 
-    public function testModify()
+    public function testModify(): void
     {
         $time  = new TimeLegacy('2017/03/10 12:00');
         $time2 = $time->modify('+1 day');
diff --git a/tests/system/I18n/TimeTest.php b/tests/system/I18n/TimeTest.php
index 0b619600d550..35a64dad695e 100644
--- a/tests/system/I18n/TimeTest.php
+++ b/tests/system/I18n/TimeTest.php
@@ -52,7 +52,7 @@ protected function tearDown(): void
         Time::setTestNow();
     }
 
-    public function testNewTimeNow()
+    public function testNewTimeNow(): void
     {
         $formatter = new IntlDateFormatter(
             'en_US',
@@ -67,7 +67,7 @@ public function testNewTimeNow()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testTimeWithTimezone()
+    public function testTimeWithTimezone(): void
     {
         $formatter = new IntlDateFormatter(
             'en_US',
@@ -83,7 +83,7 @@ public function testTimeWithTimezone()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testTimeWithTimezoneAndLocale()
+    public function testTimeWithTimezoneAndLocale(): void
     {
         $formatter = new IntlDateFormatter(
             'fr_FR',
@@ -99,7 +99,7 @@ public function testTimeWithTimezoneAndLocale()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testTimeWithDateTimeZone()
+    public function testTimeWithDateTimeZone(): void
     {
         $formatter = new IntlDateFormatter(
             'fr_FR',
@@ -115,7 +115,7 @@ public function testTimeWithDateTimeZone()
         $this->assertSame($formatter->format($time), $time->toDateTimeString());
     }
 
-    public function testToDateTime()
+    public function testToDateTime(): void
     {
         $time = new Time();
 
@@ -124,7 +124,7 @@ public function testToDateTime()
         $this->assertInstanceOf(DateTime::class, $obj);
     }
 
-    public function testNow()
+    public function testNow(): void
     {
         $time  = Time::now();
         $time1 = new DateTime();
@@ -133,7 +133,7 @@ public function testNow()
         $this->assertSame($time->getTimestamp(), $time1->getTimestamp());
     }
 
-    public function testParse()
+    public function testParse(): void
     {
         $time  = Time::parse('next Tuesday', 'America/Chicago');
         $time1 = new DateTime('now', new DateTimeZone('America/Chicago'));
@@ -142,14 +142,14 @@ public function testParse()
         $this->assertSame($time->getTimestamp(), $time1->getTimestamp());
     }
 
-    public function testToDateTimeString()
+    public function testToDateTimeString(): void
     {
         $time = Time::parse('2017-01-12 00:00', 'America/Chicago');
 
         $this->assertSame('2017-01-12 00:00:00', $time->toDateTimeString());
     }
 
-    public function testToDateTimeStringWithTimeZone()
+    public function testToDateTimeStringWithTimeZone(): void
     {
         $time = Time::parse('2017-01-12 00:00', 'Europe/London');
 
@@ -158,70 +158,70 @@ public function testToDateTimeStringWithTimeZone()
         $this->assertSame($expects->format('Y-m-d H:i:s'), $time->toDateTimeString());
     }
 
-    public function testToday()
+    public function testToday(): void
     {
         $time = Time::today();
 
         $this->assertSame(date('Y-m-d 00:00:00'), $time->toDateTimeString());
     }
 
-    public function testTodayLocalized()
+    public function testTodayLocalized(): void
     {
         $time = Time::today('Europe/London');
 
         $this->assertSame(date('Y-m-d 00:00:00'), $time->toDateTimeString());
     }
 
-    public function testYesterday()
+    public function testYesterday(): void
     {
         $time = Time::yesterday();
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('-1 day')), $time->toDateTimeString());
     }
 
-    public function testTomorrow()
+    public function testTomorrow(): void
     {
         $time = Time::tomorrow();
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('+1 day')), $time->toDateTimeString());
     }
 
-    public function testCreateFromDate()
+    public function testCreateFromDate(): void
     {
         $time = Time::createFromDate(2017, 03, 05, 'America/Chicago');
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('2017-03-05 00:00:00')), $time->toDateTimeString());
     }
 
-    public function testCreateFromDateLocalized()
+    public function testCreateFromDateLocalized(): void
     {
         $time = Time::createFromDate(2017, 03, 05, 'Europe/London');
 
         $this->assertSame(date('Y-m-d 00:00:00', strtotime('2017-03-05 00:00:00')), $time->toDateTimeString());
     }
 
-    public function testCreateFromTime()
+    public function testCreateFromTime(): void
     {
         $time = Time::createFromTime(10, 03, 05, 'America/Chicago');
 
         $this->assertSame(date('Y-m-d 10:03:05'), $time->toDateTimeString());
     }
 
-    public function testCreateFromTimeEvening()
+    public function testCreateFromTimeEvening(): void
     {
         $time = Time::createFromTime(20, 03, 05, 'America/Chicago');
 
         $this->assertSame(date('Y-m-d 20:03:05'), $time->toDateTimeString());
     }
 
-    public function testCreateFromTimeLocalized()
+    public function testCreateFromTimeLocalized(): void
     {
         $time = Time::createFromTime(10, 03, 05, 'Europe/London');
 
         $this->assertCloseEnoughString(date('Y-m-d 10:03:05'), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormat()
+    public function testCreateFromFormat(): void
     {
         $now = new DateTime('now');
 
@@ -231,14 +231,14 @@ public function testCreateFromFormat()
         $this->assertCloseEnoughString(date('2017-01-15 H:i:s', $now->getTimestamp()), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormatWithTimezoneString()
+    public function testCreateFromFormatWithTimezoneString(): void
     {
         $time = Time::createFromFormat('F j, Y', 'January 15, 2017', 'Europe/London');
 
         $this->assertCloseEnoughString(date('2017-01-15 H:i:s'), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormatWithTimezoneObject()
+    public function testCreateFromFormatWithTimezoneObject(): void
     {
         $tz = new DateTimeZone('Europe/London');
 
@@ -247,7 +247,7 @@ public function testCreateFromFormatWithTimezoneObject()
         $this->assertCloseEnoughString(date('2017-01-15 H:i:s'), $time->toDateTimeString());
     }
 
-    public function testCreateFromFormatWithInvalidFormat()
+    public function testCreateFromFormatWithInvalidFormat(): void
     {
         $format = 'foobar';
 
@@ -257,7 +257,7 @@ public function testCreateFromFormatWithInvalidFormat()
         Time::createFromFormat($format, 'America/Chicago');
     }
 
-    public function testCreateFromTimestamp()
+    public function testCreateFromTimestamp(): void
     {
         // Set the timezone temporarily to UTC to make sure the test timestamp is correct
         $tz = date_default_timezone_get();
@@ -272,7 +272,7 @@ public function testCreateFromTimestamp()
         $this->assertSame(date('2017-03-18 00:00:00'), $time->toDateTimeString());
     }
 
-    public function testCreateFromTimestampWithTimezone()
+    public function testCreateFromTimestampWithTimezone(): void
     {
         // Set the timezone temporarily to UTC to make sure the test timestamp is correct
         $tz = date_default_timezone_get();
@@ -287,7 +287,7 @@ public function testCreateFromTimestampWithTimezone()
         $this->assertSame(date('2017-03-18 07:00:00'), $time->toDateTimeString());
     }
 
-    public function testTestNow()
+    public function testTestNow(): void
     {
         $this->assertFalse(Time::hasTestNow());
         $this->assertCloseEnoughString(date('Y-m-d H:i:s', time()), Time::now()->toDateTimeString());
@@ -302,21 +302,21 @@ public function testTestNow()
         $this->assertCloseEnoughString(date('Y-m-d H:i:s', time()), Time::now()->toDateTimeString());
     }
 
-    public function testMagicIssetTrue()
+    public function testMagicIssetTrue(): void
     {
         $time = Time::parse('January 1, 2016');
 
         $this->assertTrue(isset($time->year));
     }
 
-    public function testMagicIssetFalse()
+    public function testMagicIssetFalse(): void
     {
         $time = Time::parse('January 1, 2016');
 
         $this->assertFalse(isset($time->foobar));
     }
 
-    public function testGetYear()
+    public function testGetYear(): void
     {
         $time  = Time::parse('January 1, 2016');
         $time2 = Time::parse('December 31, 2019');
@@ -325,70 +325,70 @@ public function testGetYear()
         $this->assertSame('2019', $time2->year);
     }
 
-    public function testGetMonth()
+    public function testGetMonth(): void
     {
         $time = Time::parse('August 1, 2016');
 
         $this->assertSame('8', $time->month);
     }
 
-    public function testGetDay()
+    public function testGetDay(): void
     {
         $time = Time::parse('August 12, 2016');
 
         $this->assertSame('12', $time->day);
     }
 
-    public function testGetHour()
+    public function testGetHour(): void
     {
         $time = Time::parse('August 12, 2016 4:15pm');
 
         $this->assertSame('16', $time->hour);
     }
 
-    public function testGetMinute()
+    public function testGetMinute(): void
     {
         $time = Time::parse('August 12, 2016 4:15pm');
 
         $this->assertSame('15', $time->minute);
     }
 
-    public function testGetSecond()
+    public function testGetSecond(): void
     {
         $time = Time::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('23', $time->second);
     }
 
-    public function testGetDayOfWeek()
+    public function testGetDayOfWeek(): void
     {
         $time = Time::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('6', $time->dayOfWeek);
     }
 
-    public function testGetDayOfYear()
+    public function testGetDayOfYear(): void
     {
         $time = Time::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('225', $time->dayOfYear);
     }
 
-    public function testGetWeekOfMonth()
+    public function testGetWeekOfMonth(): void
     {
         $time = Time::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('2', $time->weekOfMonth);
     }
 
-    public function testGetWeekOfYear()
+    public function testGetWeekOfYear(): void
     {
         $time = Time::parse('August 12, 2016 4:15:23pm');
 
         $this->assertSame('33', $time->weekOfYear);
     }
 
-    public function testGetTimestamp()
+    public function testGetTimestamp(): void
     {
         $time     = Time::parse('August 12, 2016 4:15:23pm');
         $expected = strtotime('August 12, 2016 4:15:23pm');
@@ -400,7 +400,7 @@ public function testGetTimestamp()
      * This test might fail if your timezone has Daylight Saving Time.
      * See https://github.com/codeigniter4/CodeIgniter4/issues/6818
      */
-    public function testGetAge()
+    public function testGetAge(): void
     {
         $time = Time::parse('5 years ago');
 
@@ -408,14 +408,14 @@ public function testGetAge()
         $this->assertSame(5, $time->age);
     }
 
-    public function testAgeNow()
+    public function testAgeNow(): void
     {
         $time = new Time();
 
         $this->assertSame(0, $time->getAge());
     }
 
-    public function testAgeFuture()
+    public function testAgeFuture(): void
     {
         Time::setTestNow('June 20, 2022', 'America/Chicago');
         $time = Time::parse('August 12, 2116 4:15:23pm');
@@ -423,7 +423,7 @@ public function testAgeFuture()
         $this->assertSame(0, $time->getAge());
     }
 
-    public function testGetAgeSameDayOfBirthday()
+    public function testGetAgeSameDayOfBirthday(): void
     {
         Time::setTestNow('December 31, 2022', 'America/Chicago');
         $time = Time::parse('December 31, 2020');
@@ -431,7 +431,7 @@ public function testGetAgeSameDayOfBirthday()
         $this->assertSame(2, $time->getAge());
     }
 
-    public function testGetAgeNextDayOfBirthday()
+    public function testGetAgeNextDayOfBirthday(): void
     {
         Time::setTestNow('January 1, 2022', 'America/Chicago');
         $time = Time::parse('December 31, 2020');
@@ -439,7 +439,7 @@ public function testGetAgeNextDayOfBirthday()
         $this->assertSame(1, $time->getAge());
     }
 
-    public function testGetAgeBeforeDayOfBirthday()
+    public function testGetAgeBeforeDayOfBirthday(): void
     {
         Time::setTestNow('December 30, 2021', 'America/Chicago');
         $time = Time::parse('December 31, 2020');
@@ -447,14 +447,14 @@ public function testGetAgeBeforeDayOfBirthday()
         $this->assertSame(0, $time->getAge());
     }
 
-    public function testGetQuarter()
+    public function testGetQuarter(): void
     {
         $time = Time::parse('April 15, 2015');
 
         $this->assertSame('2', $time->quarter);
     }
 
-    public function testGetDST()
+    public function testGetDST(): void
     {
         // America/Chicago. DST from early March -> early Nov
         $time = Time::createFromDate(2012, 1, 1, 'America/Chicago');
@@ -464,7 +464,7 @@ public function testGetDST()
         $this->assertTrue($time->dst);
     }
 
-    public function testGetDSTUnobserved()
+    public function testGetDSTUnobserved(): void
     {
         // Asia/Shanghai. DST not observed
         $tz   = new DateTimeZone('Asia/Shanghai');
@@ -473,32 +473,32 @@ public function testGetDSTUnobserved()
         $this->assertFalse($time->dst);
     }
 
-    public function testGetLocal()
+    public function testGetLocal(): void
     {
         $this->assertTrue(Time::now()->local);
         $this->assertFalse(Time::now('Europe/London')->local);
     }
 
-    public function testGetUtc()
+    public function testGetUtc(): void
     {
         $this->assertFalse(Time::now('America/Chicago')->utc);
         $this->assertTrue(Time::now('UTC')->utc);
     }
 
-    public function testGetTimezone()
+    public function testGetTimezone(): void
     {
         $instance = Time::now()->getTimezone();
 
         $this->assertInstanceOf(DateTimeZone::class, $instance);
     }
 
-    public function testGetTimezonename()
+    public function testGetTimezonename(): void
     {
         $this->assertSame('America/Chicago', Time::now('America/Chicago')->getTimezoneName());
         $this->assertSame('Europe/London', Time::now('Europe/London')->timezoneName);
     }
 
-    public function testSetYear()
+    public function testSetYear(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setYear(2015);
@@ -508,7 +508,7 @@ public function testSetYear()
         $this->assertSame('2015-05-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMonthNumber()
+    public function testSetMonthNumber(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setMonth(4);
@@ -518,7 +518,7 @@ public function testSetMonthNumber()
         $this->assertSame('2017-04-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMonthLongName()
+    public function testSetMonthLongName(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setMonth('April');
@@ -528,7 +528,7 @@ public function testSetMonthLongName()
         $this->assertSame('2017-04-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMonthShortName()
+    public function testSetMonthShortName(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setMonth('Feb');
@@ -538,7 +538,7 @@ public function testSetMonthShortName()
         $this->assertSame('2017-02-10 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetDay()
+    public function testSetDay(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setDay(15);
@@ -548,7 +548,7 @@ public function testSetDay()
         $this->assertSame('2017-05-15 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetDayOverMaxInCurrentMonth()
+    public function testSetDayOverMaxInCurrentMonth(): void
     {
         $this->expectException(I18nException::class);
 
@@ -556,7 +556,7 @@ public function testSetDayOverMaxInCurrentMonth()
         $time->setDay(29);
     }
 
-    public function testSetDayNotOverMaxInCurrentMonth()
+    public function testSetDayNotOverMaxInCurrentMonth(): void
     {
         $time  = Time::parse('Feb 02, 2012');
         $time2 = $time->setDay(29);
@@ -566,7 +566,7 @@ public function testSetDayNotOverMaxInCurrentMonth()
         $this->assertSame('2012-02-29 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetHour()
+    public function testSetHour(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setHour(15);
@@ -576,7 +576,7 @@ public function testSetHour()
         $this->assertSame('2017-05-10 15:00:00', $time2->toDateTimeString());
     }
 
-    public function testSetMinute()
+    public function testSetMinute(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setMinute(30);
@@ -586,7 +586,7 @@ public function testSetMinute()
         $this->assertSame('2017-05-10 00:30:00', $time2->toDateTimeString());
     }
 
-    public function testSetSecond()
+    public function testSetSecond(): void
     {
         $time  = Time::parse('May 10, 2017');
         $time2 = $time->setSecond(20);
@@ -596,7 +596,7 @@ public function testSetSecond()
         $this->assertSame('2017-05-10 00:00:20', $time2->toDateTimeString());
     }
 
-    public function testSetMonthTooSmall()
+    public function testSetMonthTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -604,7 +604,7 @@ public function testSetMonthTooSmall()
         $time->setMonth(-5);
     }
 
-    public function testSetMonthTooBig()
+    public function testSetMonthTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -612,7 +612,7 @@ public function testSetMonthTooBig()
         $time->setMonth(30);
     }
 
-    public function testSetDayTooSmall()
+    public function testSetDayTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -620,7 +620,7 @@ public function testSetDayTooSmall()
         $time->setDay(-5);
     }
 
-    public function testSetDayTooBig()
+    public function testSetDayTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -628,7 +628,7 @@ public function testSetDayTooBig()
         $time->setDay(80);
     }
 
-    public function testSetHourTooSmall()
+    public function testSetHourTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -636,7 +636,7 @@ public function testSetHourTooSmall()
         $time->setHour(-5);
     }
 
-    public function testSetHourTooBig()
+    public function testSetHourTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -644,7 +644,7 @@ public function testSetHourTooBig()
         $time->setHour(80);
     }
 
-    public function testSetMinuteTooSmall()
+    public function testSetMinuteTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -652,7 +652,7 @@ public function testSetMinuteTooSmall()
         $time->setMinute(-5);
     }
 
-    public function testSetMinuteTooBig()
+    public function testSetMinuteTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -660,7 +660,7 @@ public function testSetMinuteTooBig()
         $time->setMinute(80);
     }
 
-    public function testSetSecondTooSmall()
+    public function testSetSecondTooSmall(): void
     {
         $this->expectException(I18nException::class);
 
@@ -668,7 +668,7 @@ public function testSetSecondTooSmall()
         $time->setSecond(-5);
     }
 
-    public function testSetSecondTooBig()
+    public function testSetSecondTooBig(): void
     {
         $this->expectException(I18nException::class);
 
@@ -676,7 +676,7 @@ public function testSetSecondTooBig()
         $time->setSecond(80);
     }
 
-    public function testSetTimezone()
+    public function testSetTimezone(): void
     {
         $time  = Time::parse('May 10, 2017', 'America/Chicago');
         $time2 = $time->setTimezone('Europe/London');
@@ -687,7 +687,7 @@ public function testSetTimezone()
         $this->assertSame('Europe/London', $time2->getTimezoneName());
     }
 
-    public function testSetTimestamp()
+    public function testSetTimestamp(): void
     {
         $time  = Time::parse('May 10, 2017', 'America/Chicago');
         $stamp = strtotime('April 1, 2017');
@@ -698,19 +698,19 @@ public function testSetTimestamp()
         $this->assertSame('2017-04-01 00:00:00', $time2->toDateTimeString());
     }
 
-    public function testToDateString()
+    public function testToDateString(): void
     {
         $time = Time::parse('May 10, 2017', 'America/Chicago');
         $this->assertSame('2017-05-10', $time->toDateString());
     }
 
-    public function testToFormattedDateString()
+    public function testToFormattedDateString(): void
     {
         $time = Time::parse('2017-05-10', 'America/Chicago');
         $this->assertSame('May 10, 2017', $time->toFormattedDateString());
     }
 
-    public function testToTimeString()
+    public function testToTimeString(): void
     {
         $time = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $this->assertSame('13:20:33', $time->toTimeString());
@@ -718,7 +718,7 @@ public function testToTimeString()
 
     // Add/Subtract
 
-    public function testCanAddSeconds()
+    public function testCanAddSeconds(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addSeconds(10);
@@ -726,7 +726,7 @@ public function testCanAddSeconds()
         $this->assertSame('2017-01-10 13:20:43', $newTime->toDateTimeString());
     }
 
-    public function testCanAddMinutes()
+    public function testCanAddMinutes(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addMinutes(10);
@@ -734,7 +734,7 @@ public function testCanAddMinutes()
         $this->assertSame('2017-01-10 13:30:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddHours()
+    public function testCanAddHours(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addHours(3);
@@ -742,7 +742,7 @@ public function testCanAddHours()
         $this->assertSame('2017-01-10 16:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddDays()
+    public function testCanAddDays(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addDays(3);
@@ -750,7 +750,7 @@ public function testCanAddDays()
         $this->assertSame('2017-01-13 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddMonths()
+    public function testCanAddMonths(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addMonths(3);
@@ -758,7 +758,7 @@ public function testCanAddMonths()
         $this->assertSame('2017-04-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddMonthsOverYearBoundary()
+    public function testCanAddMonthsOverYearBoundary(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addMonths(13);
@@ -766,7 +766,7 @@ public function testCanAddMonthsOverYearBoundary()
         $this->assertSame('2018-02-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanAddYears()
+    public function testCanAddYears(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->addYears(3);
@@ -774,7 +774,7 @@ public function testCanAddYears()
         $this->assertSame('2020-01-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractSeconds()
+    public function testCanSubtractSeconds(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subSeconds(10);
@@ -782,7 +782,7 @@ public function testCanSubtractSeconds()
         $this->assertSame('2017-01-10 13:20:23', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractMinutes()
+    public function testCanSubtractMinutes(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subMinutes(10);
@@ -790,7 +790,7 @@ public function testCanSubtractMinutes()
         $this->assertSame('2017-01-10 13:10:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractHours()
+    public function testCanSubtractHours(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subHours(3);
@@ -798,7 +798,7 @@ public function testCanSubtractHours()
         $this->assertSame('2017-01-10 10:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractDays()
+    public function testCanSubtractDays(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subDays(3);
@@ -806,7 +806,7 @@ public function testCanSubtractDays()
         $this->assertSame('2017-01-07 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractMonths()
+    public function testCanSubtractMonths(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subMonths(3);
@@ -814,7 +814,7 @@ public function testCanSubtractMonths()
         $this->assertSame('2016-10-10 13:20:33', $newTime->toDateTimeString());
     }
 
-    public function testCanSubtractYears()
+    public function testCanSubtractYears(): void
     {
         $time    = Time::parse('January 10, 2017 13:20:33', 'America/Chicago');
         $newTime = $time->subYears(3);
@@ -824,7 +824,7 @@ public function testCanSubtractYears()
 
     // Comparison
 
-    public function testEqualWithDifferent()
+    public function testEqualWithDifferent(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = Time::parse('January 11, 2017 03:50:00', 'Europe/London');
@@ -832,7 +832,7 @@ public function testEqualWithDifferent()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithSame()
+    public function testEqualWithSame(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
@@ -840,7 +840,7 @@ public function testEqualWithSame()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithDateTime()
+    public function testEqualWithDateTime(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = new DateTime('January 11, 2017 03:50:00', new DateTimeZone('Europe/London'));
@@ -848,7 +848,7 @@ public function testEqualWithDateTime()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithSameDateTime()
+    public function testEqualWithSameDateTime(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = new DateTime('January 10, 2017 21:50:00', new DateTimeZone('America/Chicago'));
@@ -856,21 +856,21 @@ public function testEqualWithSameDateTime()
         $this->assertTrue($time1->equals($time2));
     }
 
-    public function testEqualWithString()
+    public function testEqualWithString(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertTrue($time1->equals('January 11, 2017 03:50:00', 'Europe/London'));
     }
 
-    public function testEqualWithStringAndNotimezone()
+    public function testEqualWithStringAndNotimezone(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertTrue($time1->equals('January 10, 2017 21:50:00'));
     }
 
-    public function testSameSuccess()
+    public function testSameSuccess(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
@@ -878,7 +878,7 @@ public function testSameSuccess()
         $this->assertTrue($time1->sameAs($time2));
     }
 
-    public function testSameFailure()
+    public function testSameFailure(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = Time::parse('January 11, 2017 03:50:00', 'Europe/London');
@@ -886,21 +886,21 @@ public function testSameFailure()
         $this->assertFalse($time1->sameAs($time2));
     }
 
-    public function testSameSuccessAsString()
+    public function testSameSuccessAsString(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertTrue($time1->sameAs('January 10, 2017 21:50:00', 'America/Chicago'));
     }
 
-    public function testSameFailAsString()
+    public function testSameFailAsString(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
 
         $this->assertFalse($time1->sameAs('January 11, 2017 03:50:00', 'Europe/London'));
     }
 
-    public function testBefore()
+    public function testBefore(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = Time::parse('January 11, 2017 03:50:00', 'America/Chicago');
@@ -909,7 +909,7 @@ public function testBefore()
         $this->assertFalse($time2->isBefore($time1));
     }
 
-    public function testAfter()
+    public function testAfter(): void
     {
         $time1 = Time::parse('January 10, 2017 21:50:00', 'America/Chicago');
         $time2 = Time::parse('January 11, 2017 03:50:00', 'America/Chicago');
@@ -918,7 +918,7 @@ public function testAfter()
         $this->assertTrue($time2->isAfter($time1));
     }
 
-    public function testHumanizeYearsSingle()
+    public function testHumanizeYearsSingle(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 9, 2016 12:00:00', 'America/Chicago');
@@ -926,7 +926,7 @@ public function testHumanizeYearsSingle()
         $this->assertSame('1 year ago', $time->humanize());
     }
 
-    public function testHumanizeYearsPlural()
+    public function testHumanizeYearsPlural(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 9, 2014 12:00:00', 'America/Chicago');
@@ -934,7 +934,7 @@ public function testHumanizeYearsPlural()
         $this->assertSame('3 years ago', $time->humanize());
     }
 
-    public function testHumanizeYearsForward()
+    public function testHumanizeYearsForward(): void
     {
         Time::setTestNow('January 1, 2017', 'America/Chicago');
         $time = Time::parse('January 1, 2018 12:00:00', 'America/Chicago');
@@ -942,7 +942,7 @@ public function testHumanizeYearsForward()
         $this->assertSame('in 1 year', $time->humanize());
     }
 
-    public function testHumanizeMonthsSingle()
+    public function testHumanizeMonthsSingle(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('February 9, 2017', 'America/Chicago');
@@ -950,7 +950,7 @@ public function testHumanizeMonthsSingle()
         $this->assertSame('1 month ago', $time->humanize());
     }
 
-    public function testHumanizeMonthsPlural()
+    public function testHumanizeMonthsPlural(): void
     {
         Time::setTestNow('March 1, 2017', 'America/Chicago');
         $time = Time::parse('January 1, 2017', 'America/Chicago');
@@ -958,7 +958,7 @@ public function testHumanizeMonthsPlural()
         $this->assertSame('2 months ago', $time->humanize());
     }
 
-    public function testHumanizeMonthsForward()
+    public function testHumanizeMonthsForward(): void
     {
         Time::setTestNow('March 1, 2017', 'America/Chicago');
         $time = Time::parse('April 1, 2017', 'America/Chicago');
@@ -966,7 +966,7 @@ public function testHumanizeMonthsForward()
         $this->assertSame('in 1 month', $time->humanize());
     }
 
-    public function testHumanizeDaysSingle()
+    public function testHumanizeDaysSingle(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 8, 2017', 'America/Chicago');
@@ -974,7 +974,7 @@ public function testHumanizeDaysSingle()
         $this->assertSame('2 days ago', $time->humanize());
     }
 
-    public function testHumanizeDaysPlural()
+    public function testHumanizeDaysPlural(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 8, 2017', 'America/Chicago');
@@ -982,7 +982,7 @@ public function testHumanizeDaysPlural()
         $this->assertSame('2 days ago', $time->humanize());
     }
 
-    public function testHumanizeDaysForward()
+    public function testHumanizeDaysForward(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 12, 2017', 'America/Chicago');
@@ -990,7 +990,7 @@ public function testHumanizeDaysForward()
         $this->assertSame('in 2 days', $time->humanize());
     }
 
-    public function testHumanizeDaysTomorrow()
+    public function testHumanizeDaysTomorrow(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 11, 2017', 'America/Chicago');
@@ -998,7 +998,7 @@ public function testHumanizeDaysTomorrow()
         $this->assertSame('Tomorrow', $time->humanize());
     }
 
-    public function testHumanizeDaysYesterday()
+    public function testHumanizeDaysYesterday(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 9, 2017', 'America/Chicago');
@@ -1006,7 +1006,7 @@ public function testHumanizeDaysYesterday()
         $this->assertSame('Yesterday', $time->humanize());
     }
 
-    public function testHumanizeHoursAsTime()
+    public function testHumanizeHoursAsTime(): void
     {
         Time::setTestNow('March 10, 2017 12:00', 'America/Chicago');
         $time = Time::parse('March 10, 2017 14:00', 'America/Chicago');
@@ -1014,7 +1014,7 @@ public function testHumanizeHoursAsTime()
         $this->assertSame('in 2 hours', $time->humanize());
     }
 
-    public function testHumanizeHoursAWhileAgo()
+    public function testHumanizeHoursAWhileAgo(): void
     {
         Time::setTestNow('March 10, 2017 12:00', 'America/Chicago');
         $time = Time::parse('March 10, 2017 8:00', 'America/Chicago');
@@ -1022,7 +1022,7 @@ public function testHumanizeHoursAWhileAgo()
         $this->assertSame('4 hours ago', $time->humanize());
     }
 
-    public function testHumanizeMinutesSingle()
+    public function testHumanizeMinutesSingle(): void
     {
         Time::setTestNow('March 10, 2017 12:30', 'America/Chicago');
         $time = Time::parse('March 10, 2017 12:29', 'America/Chicago');
@@ -1030,7 +1030,7 @@ public function testHumanizeMinutesSingle()
         $this->assertSame('1 minute ago', $time->humanize());
     }
 
-    public function testHumanizeMinutesPlural()
+    public function testHumanizeMinutesPlural(): void
     {
         Time::setTestNow('March 10, 2017 12:30', 'America/Chicago');
         $time = Time::parse('March 10, 2017 12:28', 'America/Chicago');
@@ -1038,7 +1038,7 @@ public function testHumanizeMinutesPlural()
         $this->assertSame('2 minutes ago', $time->humanize());
     }
 
-    public function testHumanizeMinutesForward()
+    public function testHumanizeMinutesForward(): void
     {
         Time::setTestNow('March 10, 2017 12:30', 'America/Chicago');
         $time = Time::parse('March 10, 2017 12:31', 'America/Chicago');
@@ -1046,7 +1046,7 @@ public function testHumanizeMinutesForward()
         $this->assertSame('in 1 minute', $time->humanize());
     }
 
-    public function testHumanizeWeeksSingle()
+    public function testHumanizeWeeksSingle(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 2, 2017', 'America/Chicago');
@@ -1054,7 +1054,7 @@ public function testHumanizeWeeksSingle()
         $this->assertSame('1 week ago', $time->humanize());
     }
 
-    public function testHumanizeWeeksPlural()
+    public function testHumanizeWeeksPlural(): void
     {
         Time::setTestNow('March 30, 2017', 'America/Chicago');
         $time = Time::parse('March 15, 2017', 'America/Chicago');
@@ -1062,7 +1062,7 @@ public function testHumanizeWeeksPlural()
         $this->assertSame('2 weeks ago', $time->humanize());
     }
 
-    public function testHumanizeWeeksForward()
+    public function testHumanizeWeeksForward(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 18, 2017', 'America/Chicago');
@@ -1070,7 +1070,7 @@ public function testHumanizeWeeksForward()
         $this->assertSame('in 2 weeks', $time->humanize());
     }
 
-    public function testHumanizeNow()
+    public function testHumanizeNow(): void
     {
         Time::setTestNow('March 10, 2017', 'America/Chicago');
         $time = Time::parse('March 10, 2017', 'America/Chicago');
@@ -1081,7 +1081,7 @@ public function testHumanizeNow()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/4708
      */
-    public function testHumanizeWithArLocale()
+    public function testHumanizeWithArLocale(): void
     {
         $this->resetServices();
 
@@ -1103,7 +1103,7 @@ public function testHumanizeWithArLocale()
         Locale::setDefault($currentLocale);
     }
 
-    public function testSetTimezoneDate()
+    public function testSetTimezoneDate(): void
     {
         $time  = Time::parse('13 May 2020 10:00', 'GMT');
         $time2 = $time->setTimezone('GMT+8');
@@ -1111,7 +1111,7 @@ public function testSetTimezoneDate()
         $this->assertSame('2020-05-13 18:00:00', $time2->toDateTimeString());
     }
 
-    public function testCreateFromInstance()
+    public function testCreateFromInstance(): void
     {
         $datetime = new DateTime();
         $time     = Time::createFromInstance($datetime);
@@ -1119,7 +1119,7 @@ public function testCreateFromInstance()
         $this->assertTrue($time->sameAs($datetime));
     }
 
-    public function testGetter()
+    public function testGetter(): void
     {
         $time = Time::parse('August 12, 2016 4:15:23pm');
 
@@ -1138,7 +1138,7 @@ public function testGetter()
     //        $this->assertNotSame($time1, $time2);
     //    }
 
-    public function testSetTestNowWithTimeZone()
+    public function testSetTestNowWithTimeZone(): void
     {
         Time::setTestNow('2017/03/10 12:00', 'Asia/Tokyo');
 
@@ -1147,7 +1147,7 @@ public function testSetTestNowWithTimeZone()
         $this->assertSame('2017-03-10T03:00:00+00:00', $now->format('c'));
     }
 
-    public function testSetTestNowWithFaLocale()
+    public function testSetTestNowWithFaLocale(): void
     {
         Locale::setDefault('fa');
 
@@ -1161,7 +1161,7 @@ public function testSetTestNowWithFaLocale()
     /**
      * @dataProvider provideLocales
      */
-    public function testToStringDoesNotDependOnLocale(string $locale)
+    public function testToStringDoesNotDependOnLocale(string $locale): void
     {
         Locale::setDefault($locale);
 
@@ -1180,7 +1180,7 @@ public function provideLocales(): iterable
         ];
     }
 
-    public function testModify()
+    public function testModify(): void
     {
         $time  = new Time('2017/03/10 12:00');
         $time2 = $time->modify('+1 day');
diff --git a/tests/system/Images/BaseHandlerTest.php b/tests/system/Images/BaseHandlerTest.php
index a73accd940a8..71029b31ba5e 100644
--- a/tests/system/Images/BaseHandlerTest.php
+++ b/tests/system/Images/BaseHandlerTest.php
@@ -63,13 +63,13 @@ protected function setUp(): void
         $this->path  = $this->start . 'ci-logo.png';
     }
 
-    public function testNew()
+    public function testNew(): void
     {
         $handler = Services::image('gd', null, false);
         $this->assertInstanceOf(BaseHandler::class, $handler);
     }
 
-    public function testWithFile()
+    public function testWithFile(): void
     {
         $path    = $this->origin . 'ci-logo.png';
         $handler = Services::image('gd', null, false);
@@ -81,14 +81,14 @@ public function testWithFile()
         $this->assertSame($path, $image->getPathname());
     }
 
-    public function testMissingFile()
+    public function testMissingFile(): void
     {
         $this->expectException(FileNotFoundException::class);
         $handler = Services::image('gd', null, false);
         $handler->withFile($this->start . 'No_such_file.jpg');
     }
 
-    public function testNonImageFile()
+    public function testNonImageFile(): void
     {
         $this->expectException(ImageException::class);
         $handler = Services::image('gd', null, false);
@@ -98,7 +98,7 @@ public function testNonImageFile()
         $handler->resize(100, 100);
     }
 
-    public function testForgotWithFile()
+    public function testForgotWithFile(): void
     {
         $this->expectException(ImageException::class);
         $handler = Services::image('gd', null, false);
@@ -107,7 +107,7 @@ public function testForgotWithFile()
         $handler->resize(100, 100);
     }
 
-    public function testFileTypes()
+    public function testFileTypes(): void
     {
         $handler = Services::image('gd', null, false);
         $handler->withFile($this->start . 'ci-logo.png');
@@ -124,7 +124,7 @@ public function testFileTypes()
     }
 
     // Something handled by our Image
-    public function testImageHandled()
+    public function testImageHandled(): void
     {
         $handler = Services::image('gd', null, false);
         $handler->withFile($this->path);
diff --git a/tests/system/Images/GDHandlerTest.php b/tests/system/Images/GDHandlerTest.php
index a2f9a99d4e6b..b605c54a5c9c 100644
--- a/tests/system/Images/GDHandlerTest.php
+++ b/tests/system/Images/GDHandlerTest.php
@@ -64,7 +64,7 @@ protected function setUp(): void
         $this->handler = Services::image('gd', null, false);
     }
 
-    public function testGetVersion()
+    public function testGetVersion(): void
     {
         $version = $this->handler->getVersion();
         // make sure that the call worked
@@ -74,7 +74,7 @@ public function testGetVersion()
         $this->assertLessThan(999, $version);
     }
 
-    public function testImageProperties()
+    public function testImageProperties(): void
     {
         $this->handler->withFile($this->path);
         $file  = $this->handler->getFile();
@@ -91,7 +91,7 @@ public function testImageProperties()
         $this->assertSame('width="155" height="200"', $props['size_str']);
     }
 
-    public function testImageTypeProperties()
+    public function testImageTypeProperties(): void
     {
         $this->handler->withFile($this->path);
         $file  = $this->handler->getFile();
@@ -101,7 +101,7 @@ public function testImageTypeProperties()
         $this->assertSame('image/png', $props['mime_type']);
     }
 
-    public function testResizeIgnored()
+    public function testResizeIgnored(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(155, 200); // 155x200 result
@@ -109,7 +109,7 @@ public function testResizeIgnored()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testResizeAbsolute()
+    public function testResizeAbsolute(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(123, 456, false); // 123x456 result
@@ -117,7 +117,7 @@ public function testResizeAbsolute()
         $this->assertSame(456, $this->handler->getHeight());
     }
 
-    public function testResizeAspect()
+    public function testResizeAspect(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(123, 456, true); // 123x159 result
@@ -125,7 +125,7 @@ public function testResizeAspect()
         $this->assertSame(159, $this->handler->getHeight());
     }
 
-    public function testResizeAspectWidth()
+    public function testResizeAspectWidth(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(123, 0, true); // 123x159 result
@@ -133,7 +133,7 @@ public function testResizeAspectWidth()
         $this->assertSame(159, $this->handler->getHeight());
     }
 
-    public function testResizeAspectHeight()
+    public function testResizeAspectHeight(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(0, 456, true); // 354x456 result
@@ -141,7 +141,7 @@ public function testResizeAspectHeight()
         $this->assertSame(456, $this->handler->getHeight());
     }
 
-    public function testCropTopLeft()
+    public function testCropTopLeft(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100); // 100x100 result
@@ -149,7 +149,7 @@ public function testCropTopLeft()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropMiddle()
+    public function testCropMiddle(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100, 50, 50, false); // 100x100 result
@@ -157,7 +157,7 @@ public function testCropMiddle()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropMiddlePreserved()
+    public function testCropMiddlePreserved(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100, 50, 50, true); // 78x100 result
@@ -165,7 +165,7 @@ public function testCropMiddlePreserved()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropTopLeftPreserveAspect()
+    public function testCropTopLeftPreserveAspect(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100); // 100x100 result
@@ -173,7 +173,7 @@ public function testCropTopLeftPreserveAspect()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropNothing()
+    public function testCropNothing(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(155, 200); // 155x200 result
@@ -181,7 +181,7 @@ public function testCropNothing()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testCropOutOfBounds()
+    public function testCropOutOfBounds(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100, 100); // 55x100 result in 100x100
@@ -189,7 +189,7 @@ public function testCropOutOfBounds()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testRotate()
+    public function testRotate(): void
     {
         $this->handler->withFile($this->path); // 155x200
         $this->assertSame(155, $this->handler->getWidth());
@@ -204,14 +204,14 @@ public function testRotate()
         $this->assertSame(200, $this->handler->getWidth());
     }
 
-    public function testRotateBadAngle()
+    public function testRotateBadAngle(): void
     {
         $this->handler->withFile($this->path);
         $this->expectException(ImageException::class);
         $this->handler->rotate(77);
     }
 
-    public function testFlatten()
+    public function testFlatten(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flatten();
@@ -219,7 +219,7 @@ public function testFlatten()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testFlip()
+    public function testFlip(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flip();
@@ -227,7 +227,7 @@ public function testFlip()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testHorizontal()
+    public function testHorizontal(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flip('horizontal');
@@ -235,7 +235,7 @@ public function testHorizontal()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testFlipVertical()
+    public function testFlipVertical(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flip('vertical');
@@ -243,14 +243,14 @@ public function testFlipVertical()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testFlipUnknown()
+    public function testFlipUnknown(): void
     {
         $this->handler->withFile($this->path);
         $this->expectException(ImageException::class);
         $this->handler->flip('bogus');
     }
 
-    public function testFit()
+    public function testFit(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->fit(100, 100);
@@ -258,7 +258,7 @@ public function testFit()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testFitTaller()
+    public function testFitTaller(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->fit(100, 400);
@@ -266,7 +266,7 @@ public function testFitTaller()
         $this->assertSame(400, $this->handler->getHeight());
     }
 
-    public function testFitAutoHeight()
+    public function testFitAutoHeight(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->fit(100);
@@ -274,7 +274,7 @@ public function testFitAutoHeight()
         $this->assertSame(129, $this->handler->getHeight());
     }
 
-    public function testFitPositions()
+    public function testFitPositions(): void
     {
         $choices = [
             'top-left',
@@ -296,7 +296,7 @@ public function testFitPositions()
         }
     }
 
-    public function testText()
+    public function testText(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->text(
@@ -307,7 +307,7 @@ public function testText()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testMoreText()
+    public function testMoreText(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->text('vertical', ['vAlign' => 'middle', 'withShadow' => 'sure', 'shadowOffset' => 3]);
@@ -315,7 +315,7 @@ public function testMoreText()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testImageCreation()
+    public function testImageCreation(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! function_exists('imagecreatefromwebp')) {
@@ -330,7 +330,7 @@ public function testImageCreation()
         }
     }
 
-    public function testImageCopy()
+    public function testImageCopy(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! function_exists('imagecreatefromwebp')) {
@@ -349,7 +349,7 @@ public function testImageCopy()
         }
     }
 
-    public function testImageCopyWithNoTargetAndMaxQuality()
+    public function testImageCopyWithNoTargetAndMaxQuality(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             $this->handler->withFile($this->origin . 'ci-logo.' . $type);
@@ -363,7 +363,7 @@ public function testImageCopyWithNoTargetAndMaxQuality()
         }
     }
 
-    public function testImageCompressionGetResource()
+    public function testImageCompressionGetResource(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! function_exists('imagecreatefromwebp')) {
@@ -383,7 +383,7 @@ public function testImageCompressionGetResource()
         }
     }
 
-    public function testImageCompressionWithResource()
+    public function testImageCompressionWithResource(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! function_exists('imagecreatefromwebp')) {
@@ -404,7 +404,7 @@ public function testImageCompressionWithResource()
         }
     }
 
-    public function testImageConvert()
+    public function testImageConvert(): void
     {
         $this->handler->withFile($this->origin . 'ci-logo.jpeg');
         $this->handler->convert(IMAGETYPE_PNG);
@@ -412,7 +412,7 @@ public function testImageConvert()
         $this->assertSame(exif_imagetype($this->start . 'work/ci-logo.png'), IMAGETYPE_PNG);
     }
 
-    public function testImageReorientLandscape()
+    public function testImageReorientLandscape(): void
     {
         for ($i = 0; $i <= 8; $i++) {
             $source = $this->origin . 'EXIFsamples/landscape_' . $i . '.jpg';
@@ -428,7 +428,7 @@ public function testImageReorientLandscape()
         }
     }
 
-    public function testImageReorientPortrait()
+    public function testImageReorientPortrait(): void
     {
         for ($i = 0; $i <= 8; $i++) {
             $source = $this->origin . 'EXIFsamples/portrait_' . $i . '.jpg';
diff --git a/tests/system/Images/ImageMagickHandlerTest.php b/tests/system/Images/ImageMagickHandlerTest.php
index 0e62c01220fe..69a5df6e687c 100644
--- a/tests/system/Images/ImageMagickHandlerTest.php
+++ b/tests/system/Images/ImageMagickHandlerTest.php
@@ -62,7 +62,7 @@ protected function setUp(): void
         $this->handler = Services::image('imagick', $handlerConfig, false);
     }
 
-    public function testGetVersion()
+    public function testGetVersion(): void
     {
         $version = $this->handler->getVersion();
         // make sure that the call worked
@@ -72,7 +72,7 @@ public function testGetVersion()
         $this->assertLessThan(0, version_compare($version, '99.0.0'));
     }
 
-    public function testImageProperties()
+    public function testImageProperties(): void
     {
         $this->handler->withFile($this->path);
         $file  = $this->handler->getFile();
@@ -89,7 +89,7 @@ public function testImageProperties()
         $this->assertSame('width="155" height="200"', $props['size_str']);
     }
 
-    public function testImageTypeProperties()
+    public function testImageTypeProperties(): void
     {
         $this->handler->withFile($this->path);
         $file  = $this->handler->getFile();
@@ -99,7 +99,7 @@ public function testImageTypeProperties()
         $this->assertSame('image/png', $props['mime_type']);
     }
 
-    public function testResizeIgnored()
+    public function testResizeIgnored(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(155, 200); // 155x200 result
@@ -107,7 +107,7 @@ public function testResizeIgnored()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testResizeAbsolute()
+    public function testResizeAbsolute(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(123, 456, false); // 123x456 result
@@ -115,7 +115,7 @@ public function testResizeAbsolute()
         $this->assertSame(456, $this->handler->getHeight());
     }
 
-    public function testResizeAspect()
+    public function testResizeAspect(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(123, 456, true); // 123x159 result
@@ -123,7 +123,7 @@ public function testResizeAspect()
         $this->assertSame(159, $this->handler->getHeight());
     }
 
-    public function testResizeAspectWidth()
+    public function testResizeAspectWidth(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(123, 0, true); // 123x159 result
@@ -131,7 +131,7 @@ public function testResizeAspectWidth()
         $this->assertSame(159, $this->handler->getHeight());
     }
 
-    public function testResizeAspectHeight()
+    public function testResizeAspectHeight(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->resize(0, 456, true); // 353x456 result
@@ -139,7 +139,7 @@ public function testResizeAspectHeight()
         $this->assertSame(456, $this->handler->getHeight());
     }
 
-    public function testCropTopLeft()
+    public function testCropTopLeft(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100); // 100x100 result
@@ -147,7 +147,7 @@ public function testCropTopLeft()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropMiddle()
+    public function testCropMiddle(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100, 50, 50, false); // 100x100 result
@@ -155,7 +155,7 @@ public function testCropMiddle()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropMiddlePreserved()
+    public function testCropMiddlePreserved(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100, 50, 50, true); // 78x100 result
@@ -163,7 +163,7 @@ public function testCropMiddlePreserved()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropTopLeftPreserveAspect()
+    public function testCropTopLeftPreserveAspect(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100); // 100x100 result
@@ -171,7 +171,7 @@ public function testCropTopLeftPreserveAspect()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testCropNothing()
+    public function testCropNothing(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(155, 200); // 155x200 result
@@ -179,7 +179,7 @@ public function testCropNothing()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testCropOutOfBounds()
+    public function testCropOutOfBounds(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->crop(100, 100, 100); // 55x100 result in 100x100
@@ -187,7 +187,7 @@ public function testCropOutOfBounds()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testRotate()
+    public function testRotate(): void
     {
         $this->handler->withFile($this->path); // 155x200
         $this->assertSame(155, $this->handler->getWidth());
@@ -202,14 +202,14 @@ public function testRotate()
         $this->assertSame(200, $this->handler->getWidth());
     }
 
-    public function testRotateBadAngle()
+    public function testRotateBadAngle(): void
     {
         $this->handler->withFile($this->path);
         $this->expectException(ImageException::class);
         $this->handler->rotate(77);
     }
 
-    public function testFlatten()
+    public function testFlatten(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flatten();
@@ -217,7 +217,7 @@ public function testFlatten()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testFlip()
+    public function testFlip(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flip();
@@ -225,7 +225,7 @@ public function testFlip()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testHorizontal()
+    public function testHorizontal(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flip('horizontal');
@@ -233,7 +233,7 @@ public function testHorizontal()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testFlipVertical()
+    public function testFlipVertical(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->flip('vertical');
@@ -241,14 +241,14 @@ public function testFlipVertical()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testFlipUnknown()
+    public function testFlipUnknown(): void
     {
         $this->handler->withFile($this->path);
         $this->expectException(ImageException::class);
         $this->handler->flip('bogus');
     }
 
-    public function testFit()
+    public function testFit(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->fit(100, 100);
@@ -256,7 +256,7 @@ public function testFit()
         $this->assertSame(100, $this->handler->getHeight());
     }
 
-    public function testFitTaller()
+    public function testFitTaller(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->fit(100, 400);
@@ -264,7 +264,7 @@ public function testFitTaller()
         $this->assertSame(400, $this->handler->getHeight());
     }
 
-    public function testFitAutoHeight()
+    public function testFitAutoHeight(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->fit(100);
@@ -272,7 +272,7 @@ public function testFitAutoHeight()
         $this->assertSame(129, $this->handler->getHeight());
     }
 
-    public function testFitPositions()
+    public function testFitPositions(): void
     {
         $choices = [
             'top-left',
@@ -294,7 +294,7 @@ public function testFitPositions()
         }
     }
 
-    public function testText()
+    public function testText(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->text('vertical', ['hAlign' => 'right', 'vAlign' => 'bottom']);
@@ -302,7 +302,7 @@ public function testText()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testMoreText()
+    public function testMoreText(): void
     {
         $this->handler->withFile($this->path);
         $this->handler->text('vertical', ['vAlign' => 'middle', 'withShadow' => 'sure', 'shadowOffset' => 3]);
@@ -310,7 +310,7 @@ public function testMoreText()
         $this->assertSame(200, $this->handler->getHeight());
     }
 
-    public function testImageCreation()
+    public function testImageCreation(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! in_array('WEBP', Imagick::queryFormats(), true)) {
@@ -325,7 +325,7 @@ public function testImageCreation()
         }
     }
 
-    public function testImageCopy()
+    public function testImageCopy(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! in_array('WEBP', Imagick::queryFormats(), true)) {
@@ -344,7 +344,7 @@ public function testImageCopy()
         }
     }
 
-    public function testImageCopyWithNoTargetAndMaxQuality()
+    public function testImageCopyWithNoTargetAndMaxQuality(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             $this->handler->withFile($this->origin . 'ci-logo.' . $type);
@@ -358,7 +358,7 @@ public function testImageCopyWithNoTargetAndMaxQuality()
         }
     }
 
-    public function testImageCompressionGetResource()
+    public function testImageCompressionGetResource(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! in_array('WEBP', Imagick::queryFormats(), true)) {
@@ -378,7 +378,7 @@ public function testImageCompressionGetResource()
         }
     }
 
-    public function testImageCompressionWithResource()
+    public function testImageCompressionWithResource(): void
     {
         foreach (['gif', 'jpeg', 'png', 'webp'] as $type) {
             if ($type === 'webp' && ! in_array('WEBP', Imagick::queryFormats(), true)) {
@@ -399,7 +399,7 @@ public function testImageCompressionWithResource()
         }
     }
 
-    public function testImageConvert()
+    public function testImageConvert(): void
     {
         $this->handler->withFile($this->origin . 'ci-logo.jpeg');
         $this->handler->convert(IMAGETYPE_PNG);
@@ -407,7 +407,7 @@ public function testImageConvert()
         $this->assertSame(exif_imagetype($this->root . 'ci-logo.png'), IMAGETYPE_PNG);
     }
 
-    public function testImageReorientLandscape()
+    public function testImageReorientLandscape(): void
     {
         for ($i = 0; $i <= 8; $i++) {
             $source = $this->origin . 'EXIFsamples/landscape_' . $i . '.jpg';
@@ -426,7 +426,7 @@ public function testImageReorientLandscape()
         }
     }
 
-    public function testImageReorientPortrait()
+    public function testImageReorientPortrait(): void
     {
         for ($i = 0; $i <= 8; $i++) {
             $source = $this->origin . 'EXIFsamples/portrait_' . $i . '.jpg';
diff --git a/tests/system/Images/ImageTest.php b/tests/system/Images/ImageTest.php
index e04ea6417518..5ed826a116c4 100644
--- a/tests/system/Images/ImageTest.php
+++ b/tests/system/Images/ImageTest.php
@@ -49,7 +49,7 @@ protected function setUp(): void
         $this->image = new Image($this->start . 'ci-logo.png');
     }
 
-    public function testBasicPropertiesInherited()
+    public function testBasicPropertiesInherited(): void
     {
         $this->assertSame('ci-logo.png', $this->image->getFilename());
         $this->assertSame($this->start . 'ci-logo.png', $this->image->getPathname());
@@ -57,7 +57,7 @@ public function testBasicPropertiesInherited()
         $this->assertSame('ci-logo.png', $this->image->getBasename());
     }
 
-    public function testGetProperties()
+    public function testGetProperties(): void
     {
         $expected = [
             'width'      => 155,
@@ -70,7 +70,7 @@ public function testGetProperties()
         $this->assertSame($expected, $this->image->getProperties(true));
     }
 
-    public function testExtractProperties()
+    public function testExtractProperties(): void
     {
         // extract properties from the image
         $this->assertTrue($this->image->getProperties(false));
@@ -82,27 +82,27 @@ public function testExtractProperties()
         $this->assertSame('image/png', $this->image->mime);
     }
 
-    public function testCopyDefaultName()
+    public function testCopyDefaultName(): void
     {
         $targetPath = $this->start . 'work';
         $this->image->copy($targetPath);
         $this->assertTrue($this->root->hasChild('work/ci-logo.png'));
     }
 
-    public function testCopyNewName()
+    public function testCopyNewName(): void
     {
         $this->image->copy($this->root->url(), 'new-logo.png');
         $this->assertTrue($this->root->hasChild('new-logo.png'));
     }
 
-    public function testCopyNewFolder()
+    public function testCopyNewFolder(): void
     {
         $targetPath = $this->start . 'work/subfolder';
         $this->image->copy($targetPath, 'new-logo.png');
         $this->assertTrue($this->root->hasChild('work/subfolder/new-logo.png'));
     }
 
-    public function testCopyNowhere()
+    public function testCopyNowhere(): void
     {
         $this->expectException(ImageException::class);
         $targetPath = $this->start . 'work';
diff --git a/tests/system/Language/LanguageTest.php b/tests/system/Language/LanguageTest.php
index 7f89baaa37b8..27c1b6bee346 100644
--- a/tests/system/Language/LanguageTest.php
+++ b/tests/system/Language/LanguageTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->lang = new MockLanguage('en');
     }
 
-    public function testReturnsStringWithNoFileInMessage()
+    public function testReturnsStringWithNoFileInMessage(): void
     {
         $this->assertSame('something', $this->lang->getLine('something'));
     }
@@ -39,7 +39,7 @@ public function testReturnsStringWithNoFileInMessage()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3822
      */
-    public function testReturnParsedStringWithNoFileInMessage()
+    public function testReturnParsedStringWithNoFileInMessage(): void
     {
         $this->lang->setLocale('en-GB');
 
@@ -49,7 +49,7 @@ public function testReturnParsedStringWithNoFileInMessage()
         $this->assertSame('£7.41', lang($line, ['price' => '7.41'], 'en-GB'));
     }
 
-    public function testGetLineReturnsLine()
+    public function testGetLineReturnsLine(): void
     {
         $this->lang->setData('books', [
             'bookSaved'  => 'We kept the book free from the boogeyman',
@@ -59,7 +59,7 @@ public function testGetLineReturnsLine()
         $this->assertSame('We saved some more', $this->lang->getLine('books.booksSaved'));
     }
 
-    public function testGetLineReturnsFallbackLine()
+    public function testGetLineReturnsFallbackLine(): void
     {
         $this->lang
             ->setLocale('en-US')
@@ -81,7 +81,7 @@ public function testGetLineReturnsFallbackLine()
         $this->assertSame('equivalent.unknown', $this->lang->getLine('equivalent.unknown'));
     }
 
-    public function testGetLineArrayReturnsLineArray()
+    public function testGetLineArrayReturnsLineArray(): void
     {
         $this->lang->setData('books', [
             'booksList' => [
@@ -96,7 +96,7 @@ public function testGetLineArrayReturnsLineArray()
         ], $this->lang->getLine('books.booksList'));
     }
 
-    public function testGetLineFormatsMessage()
+    public function testGetLineFormatsMessage(): void
     {
         // No intl extension? then we can't test this - go away....
         if (! class_exists(MessageFormatter::class)) {
@@ -110,7 +110,7 @@ public function testGetLineFormatsMessage()
         $this->assertSame('45 books have been saved.', $this->lang->getLine('books.bookCount', [91 / 2]));
     }
 
-    public function testGetLineArrayFormatsMessages()
+    public function testGetLineArrayFormatsMessages(): void
     {
         // No intl extension? Then we can't test this - go away...
         if (! class_exists(MessageFormatter::class)) {
@@ -129,7 +129,7 @@ public function testGetLineArrayFormatsMessages()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/891
      */
-    public function testLangAllowsOtherLocales()
+    public function testLangAllowsOtherLocales(): void
     {
         $str1 = lang('Language.languageGetLineInvalidArgumentException', [], 'en');
         $str2 = lang('Language.languageGetLineInvalidArgumentException', [], 'ru');
@@ -138,7 +138,7 @@ public function testLangAllowsOtherLocales()
         $this->assertSame('Whatever this would be, translated', $str2);
     }
 
-    public function testLangDoesntFormat()
+    public function testLangDoesntFormat(): void
     {
         $this->lang->disableIntlSupport();
 
@@ -151,7 +151,7 @@ public function testLangDoesntFormat()
         $this->assertSame(['{0, number, integer} related books.'], $this->lang->getLine('books.bookList', [15]));
     }
 
-    public function testLanguageDuplicateKey()
+    public function testLanguageDuplicateKey(): void
     {
         $this->lang = new Language('en');
         $this->assertSame('These are not the droids you are looking for', $this->lang->getLine('More.strongForce', []));
@@ -160,7 +160,7 @@ public function testLanguageDuplicateKey()
         $this->assertSame('I have a very bad feeling about this', $this->lang->getLine('More.cannotMove', []));
     }
 
-    public function testLanguageFileLoading()
+    public function testLanguageFileLoading(): void
     {
         $this->lang = new SecondMockLanguage('en');
 
@@ -171,7 +171,7 @@ public function testLanguageFileLoading()
         $this->assertCount(1, $this->lang->loaded()); // should only be there once
     }
 
-    public function testLanguageFileLoadingReturns()
+    public function testLanguageFileLoadingReturns(): void
     {
         $this->lang = new SecondMockLanguage('en');
 
@@ -184,7 +184,7 @@ public function testLanguageFileLoadingReturns()
         $this->assertCount(1, $this->lang->loaded());
     }
 
-    public function testLanguageSameKeyAndFileName()
+    public function testLanguageSameKeyAndFileName(): void
     {
         // first file data | example.message
         $this->lang->setData('example', ['message' => 'This is an example message']);
@@ -198,13 +198,13 @@ public function testLanguageSameKeyAndFileName()
         $this->assertSame('Another example', $this->lang->getLine('another.example'));
     }
 
-    public function testGetLocale()
+    public function testGetLocale(): void
     {
         $this->lang = Services::language('en', false);
         $this->assertSame('en', $this->lang->getLocale());
     }
 
-    public function testPrioritizedLocator()
+    public function testPrioritizedLocator(): void
     {
         // this should load the replacement bundle of messages
         $message = lang('Core.missingExtension', [], 'en');
@@ -248,7 +248,7 @@ public function MessageBundles(): iterable
      *
      * @param mixed $bundle
      */
-    public function testBundleUniqueKeys($bundle)
+    public function testBundleUniqueKeys($bundle): void
     {
         $messages = require SYSTEMPATH . 'Language/en/' . $bundle . '.php';
         $this->assertGreaterThan(0, count($messages));
@@ -256,7 +256,7 @@ public function testBundleUniqueKeys($bundle)
 
     // Testing base locale vs variants
 
-    public function testBaseFallbacks()
+    public function testBaseFallbacks(): void
     {
         $this->lang = Services::language('en-ZZ', false);
         // key is in both base and variant; should pick variant
@@ -275,7 +275,7 @@ public function testBaseFallbacks()
     /**
      * Test if after using lang() with a locale the Language class keep the locale after return the $line
      */
-    public function testLangKeepLocale()
+    public function testLangKeepLocale(): void
     {
         $this->lang = Services::language('en', true);
 
@@ -302,7 +302,7 @@ public function testLangKeepLocale()
      * six	Y	Y	N
      * sev	Y	Y	Y
      */
-    public function testAllTheWayFallbacks()
+    public function testAllTheWayFallbacks(): void
     {
         $this->lang = Services::language('ab-CD', false);
         $this->assertSame('Allin.none', $this->lang->getLine('Allin.none'));
@@ -315,7 +315,7 @@ public function testAllTheWayFallbacks()
         $this->assertSame('Hanging Gardens of Babylon', $this->lang->getLine('Allin.sev'));
     }
 
-    public function testLanguageNestedArrayDefinition()
+    public function testLanguageNestedArrayDefinition(): void
     {
         $this->lang = new SecondMockLanguage('en');
         $this->lang->loadem('Nested', 'en');
@@ -323,7 +323,7 @@ public function testLanguageNestedArrayDefinition()
         $this->assertSame('e', $this->lang->getLine('Nested.a.b.c.d'));
     }
 
-    public function testLanguageKeySeparatedByDot()
+    public function testLanguageKeySeparatedByDot(): void
     {
         $this->lang = new SecondMockLanguage('en');
         $this->lang->loadem('Foo', 'en');
diff --git a/tests/system/Log/Handlers/ChromeLoggerHandlerTest.php b/tests/system/Log/Handlers/ChromeLoggerHandlerTest.php
index 88a27b45b351..a3cf548f518e 100644
--- a/tests/system/Log/Handlers/ChromeLoggerHandlerTest.php
+++ b/tests/system/Log/Handlers/ChromeLoggerHandlerTest.php
@@ -25,7 +25,7 @@
  */
 final class ChromeLoggerHandlerTest extends CIUnitTestCase
 {
-    public function testCanHandleLogLevel()
+    public function testCanHandleLogLevel(): void
     {
         $config = new LoggerConfig();
 
@@ -35,7 +35,7 @@ public function testCanHandleLogLevel()
         $this->assertFalse($logger->canHandle('foo'));
     }
 
-    public function testHandle()
+    public function testHandle(): void
     {
         $config = new LoggerConfig();
 
@@ -45,7 +45,7 @@ public function testHandle()
         $this->assertTrue($logger->handle('warning', 'This a log test'));
     }
 
-    public function testSendLogs()
+    public function testSendLogs(): void
     {
         $config = new LoggerConfig();
 
@@ -59,7 +59,7 @@ public function testSendLogs()
         $this->assertTrue($response->hasHeader('X-ChromeLogger-Data'));
     }
 
-    public function testSetDateFormat()
+    public function testSetDateFormat(): void
     {
         $config = new LoggerConfig();
 
@@ -73,7 +73,7 @@ public function testSetDateFormat()
         $this->assertSame('F j, Y', $this->getPrivateProperty($logger, 'dateFormat'));
     }
 
-    public function testChromeLoggerHeaderSent()
+    public function testChromeLoggerHeaderSent(): void
     {
         Services::injectMock('response', new MockResponse(new App()));
         $response = service('response');
diff --git a/tests/system/Log/Handlers/FileHandlerTest.php b/tests/system/Log/Handlers/FileHandlerTest.php
index 2056561c999b..024efd42bb75 100644
--- a/tests/system/Log/Handlers/FileHandlerTest.php
+++ b/tests/system/Log/Handlers/FileHandlerTest.php
@@ -35,7 +35,7 @@ protected function setUp(): void
         $this->start = $this->root->url() . '/';
     }
 
-    public function testHandle()
+    public function testHandle(): void
     {
         $config = new LoggerConfig();
 
@@ -46,7 +46,7 @@ public function testHandle()
         $this->assertTrue($logger->handle('warning', 'This is a test log'));
     }
 
-    public function testBasicHandle()
+    public function testBasicHandle(): void
     {
         $config                                          = new LoggerConfig();
         $config->handlers[TestHandler::class]['path']    = $this->start . 'charlie/';
@@ -59,7 +59,7 @@ public function testBasicHandle()
         $this->assertTrue($logger->handle('warning', 'This is a test log'));
     }
 
-    public function testHandleCreateFile()
+    public function testHandleCreateFile(): void
     {
         $config                                       = new LoggerConfig();
         $config->handlers[TestHandler::class]['path'] = $this->start;
@@ -79,7 +79,7 @@ public function testHandleCreateFile()
         $this->assertStringContainsString($expectedResult, $line);
     }
 
-    public function testHandleDateTimeCorrectly()
+    public function testHandleDateTimeCorrectly(): void
     {
         $config                                       = new LoggerConfig();
         $config->handlers[TestHandler::class]['path'] = $this->start;
diff --git a/tests/system/Log/LoggerTest.php b/tests/system/Log/LoggerTest.php
index c171812ace3c..317ad9c14bf4 100644
--- a/tests/system/Log/LoggerTest.php
+++ b/tests/system/Log/LoggerTest.php
@@ -25,7 +25,7 @@
  */
 final class LoggerTest extends CIUnitTestCase
 {
-    public function testThrowsExceptionWithBadHandlerSettings()
+    public function testThrowsExceptionWithBadHandlerSettings(): void
     {
         $config           = new LoggerConfig();
         $config->handlers = null;
@@ -36,7 +36,7 @@ public function testThrowsExceptionWithBadHandlerSettings()
         new Logger($config);
     }
 
-    public function testLogThrowsExceptionOnInvalidLevel()
+    public function testLogThrowsExceptionOnInvalidLevel(): void
     {
         $config = new LoggerConfig();
 
@@ -48,7 +48,7 @@ public function testLogThrowsExceptionOnInvalidLevel()
         $logger->log('foo', '');
     }
 
-    public function testLogReturnsFalseWhenLogNotHandled()
+    public function testLogReturnsFalseWhenLogNotHandled(): void
     {
         $config            = new LoggerConfig();
         $config->threshold = 3;
@@ -58,7 +58,7 @@ public function testLogReturnsFalseWhenLogNotHandled()
         $this->assertFalse($logger->log('debug', ''));
     }
 
-    public function testLogActuallyLogs()
+    public function testLogActuallyLogs(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -72,7 +72,7 @@ public function testLogActuallyLogs()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogDoesnotLogUnhandledLevels()
+    public function testLogDoesnotLogUnhandledLevels(): void
     {
         $config = new LoggerConfig();
 
@@ -87,7 +87,7 @@ public function testLogDoesnotLogUnhandledLevels()
         $this->assertCount(0, $logs);
     }
 
-    public function testLogInterpolatesMessage()
+    public function testLogInterpolatesMessage(): void
     {
         $config = new LoggerConfig();
 
@@ -103,7 +103,7 @@ public function testLogInterpolatesMessage()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogInterpolatesPost()
+    public function testLogInterpolatesPost(): void
     {
         $config = new LoggerConfig();
 
@@ -120,7 +120,7 @@ public function testLogInterpolatesPost()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogInterpolatesGet()
+    public function testLogInterpolatesGet(): void
     {
         $config = new LoggerConfig();
 
@@ -137,7 +137,7 @@ public function testLogInterpolatesGet()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogInterpolatesSession()
+    public function testLogInterpolatesSession(): void
     {
         $config = new LoggerConfig();
 
@@ -154,7 +154,7 @@ public function testLogInterpolatesSession()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogInterpolatesCurrentEnvironment()
+    public function testLogInterpolatesCurrentEnvironment(): void
     {
         $config = new LoggerConfig();
 
@@ -170,7 +170,7 @@ public function testLogInterpolatesCurrentEnvironment()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogInterpolatesEnvironmentVars()
+    public function testLogInterpolatesEnvironmentVars(): void
     {
         $config = new LoggerConfig();
 
@@ -188,7 +188,7 @@ public function testLogInterpolatesEnvironmentVars()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogInterpolatesFileAndLine()
+    public function testLogInterpolatesFileAndLine(): void
     {
         $config = new LoggerConfig();
 
@@ -205,7 +205,7 @@ public function testLogInterpolatesFileAndLine()
         $this->assertGreaterThan(1, strpos($logs[0], $expected));
     }
 
-    public function testLogInterpolatesExceptions()
+    public function testLogInterpolatesExceptions(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -224,7 +224,7 @@ public function testLogInterpolatesExceptions()
         $this->assertSame(0, strpos($logs[0], $expected));
     }
 
-    public function testEmergencyLogsCorrectly()
+    public function testEmergencyLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -239,7 +239,7 @@ public function testEmergencyLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testAlertLogsCorrectly()
+    public function testAlertLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -254,7 +254,7 @@ public function testAlertLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testCriticalLogsCorrectly()
+    public function testCriticalLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -269,7 +269,7 @@ public function testCriticalLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testErrorLogsCorrectly()
+    public function testErrorLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -284,7 +284,7 @@ public function testErrorLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testWarningLogsCorrectly()
+    public function testWarningLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -299,7 +299,7 @@ public function testWarningLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testNoticeLogsCorrectly()
+    public function testNoticeLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -314,7 +314,7 @@ public function testNoticeLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testInfoLogsCorrectly()
+    public function testInfoLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -329,7 +329,7 @@ public function testInfoLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testDebugLogsCorrectly()
+    public function testDebugLogsCorrectly(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -344,7 +344,7 @@ public function testDebugLogsCorrectly()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testLogLevels()
+    public function testLogLevels(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -359,7 +359,7 @@ public function testLogLevels()
         $this->assertSame($expected, $logs[0]);
     }
 
-    public function testNonStringMessage()
+    public function testNonStringMessage(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
@@ -373,7 +373,7 @@ public function testNonStringMessage()
         $this->assertStringContainsString($expected, $logs[0]);
     }
 
-    public function testDetermineFileNoStackTrace()
+    public function testDetermineFileNoStackTrace(): void
     {
         $config = new LoggerConfig();
         $logger = new Logger($config);
diff --git a/tests/system/Models/MiscellaneousModelTest.php b/tests/system/Models/MiscellaneousModelTest.php
index a9a586912d42..554f91c89580 100644
--- a/tests/system/Models/MiscellaneousModelTest.php
+++ b/tests/system/Models/MiscellaneousModelTest.php
@@ -30,7 +30,7 @@ public function testChunk(): void
     {
         $rowCount = 0;
 
-        $this->createModel(UserModel::class)->chunk(2, static function ($row) use (&$rowCount) {
+        $this->createModel(UserModel::class)->chunk(2, static function ($row) use (&$rowCount): void {
             $rowCount++;
         });
 
diff --git a/tests/system/Models/ValidationModelRuleGroupTest.php b/tests/system/Models/ValidationModelRuleGroupTest.php
index f25dfbbf9735..0064b4f0c9ed 100644
--- a/tests/system/Models/ValidationModelRuleGroupTest.php
+++ b/tests/system/Models/ValidationModelRuleGroupTest.php
@@ -363,7 +363,7 @@ public function testGetValidationMessages(): void
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6577
      */
-    public function testUpdateEntityWithPropertyCleanValidationRulesTrueAndCallingCleanRulesFalse()
+    public function testUpdateEntityWithPropertyCleanValidationRulesTrueAndCallingCleanRulesFalse(): void
     {
         $model = new class () extends Model {
             protected $table           = 'test';
@@ -401,7 +401,7 @@ public function testUpdateEntityWithPropertyCleanValidationRulesTrueAndCallingCl
         );
     }
 
-    public function testUpdateEntityWithPropertyCleanValidationRulesFalse()
+    public function testUpdateEntityWithPropertyCleanValidationRulesFalse(): void
     {
         $model = new class () extends Model {
             protected $table           = 'test';
@@ -441,7 +441,7 @@ public function testUpdateEntityWithPropertyCleanValidationRulesFalse()
         );
     }
 
-    public function testInsertEntityValidateEntireRules()
+    public function testInsertEntityValidateEntireRules(): void
     {
         $model = new class () extends Model {
             protected $table           = 'test';
diff --git a/tests/system/Models/ValidationModelTest.php b/tests/system/Models/ValidationModelTest.php
index 50c42b350fd4..c709273c694a 100644
--- a/tests/system/Models/ValidationModelTest.php
+++ b/tests/system/Models/ValidationModelTest.php
@@ -375,7 +375,7 @@ public function testGetValidationMessages(): void
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/6577
      */
-    public function testUpdateEntityWithPropertyCleanValidationRulesTrueAndCallingCleanRulesFalse()
+    public function testUpdateEntityWithPropertyCleanValidationRulesTrueAndCallingCleanRulesFalse(): void
     {
         $model = new class () extends Model {
             protected $table           = 'test';
@@ -413,7 +413,7 @@ public function testUpdateEntityWithPropertyCleanValidationRulesTrueAndCallingCl
         );
     }
 
-    public function testUpdateEntityWithPropertyCleanValidationRulesFalse()
+    public function testUpdateEntityWithPropertyCleanValidationRulesFalse(): void
     {
         $model = new class () extends Model {
             protected $table           = 'test';
@@ -453,7 +453,7 @@ public function testUpdateEntityWithPropertyCleanValidationRulesFalse()
         );
     }
 
-    public function testInsertEntityValidateEntireRules()
+    public function testInsertEntityValidateEntireRules(): void
     {
         $model = new class () extends Model {
             protected $table           = 'test';
diff --git a/tests/system/Pager/PagerRendererTest.php b/tests/system/Pager/PagerRendererTest.php
index 1df7f7c8c4ea..7d57e66e8e79 100644
--- a/tests/system/Pager/PagerRendererTest.php
+++ b/tests/system/Pager/PagerRendererTest.php
@@ -32,7 +32,7 @@ protected function setUp(): void
         $this->expect = 'http://example.com/foo?page=';
     }
 
-    public function testHasPreviousReturnsFalseWhenFirstIsOne()
+    public function testHasPreviousReturnsFalseWhenFirstIsOne(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -46,7 +46,7 @@ public function testHasPreviousReturnsFalseWhenFirstIsOne()
         $this->assertFalse($pager->hasPrevious());
     }
 
-    public function testHasPreviousReturnsTrueWhenFirstIsMoreThanOne()
+    public function testHasPreviousReturnsTrueWhenFirstIsMoreThanOne(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -65,7 +65,7 @@ public function testHasPreviousReturnsTrueWhenFirstIsMoreThanOne()
         $this->assertSame('http://example.com/foo?foo=bar&page=2', $pager->getPrevious());
     }
 
-    public function testGetPreviousWhenSurroundCountIsZero()
+    public function testGetPreviousWhenSurroundCountIsZero(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -84,7 +84,7 @@ public function testGetPreviousWhenSurroundCountIsZero()
         $this->assertSame('http://example.com/foo?foo=bar&page=3', $pager->getPrevious());
     }
 
-    public function testHasNextReturnsFalseWhenLastIsTotal()
+    public function testHasNextReturnsFalseWhenLastIsTotal(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -102,7 +102,7 @@ public function testHasNextReturnsFalseWhenLastIsTotal()
         $this->assertFalse($pager->hasNext());
     }
 
-    public function testHasNextReturnsTrueWhenLastIsSmallerThanTotal()
+    public function testHasNextReturnsTrueWhenLastIsSmallerThanTotal(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -121,7 +121,7 @@ public function testHasNextReturnsTrueWhenLastIsSmallerThanTotal()
         $this->assertSame('http://example.com/foo?foo=bar&page=7', $pager->getNext());
     }
 
-    public function testGetNextWhenSurroundCountIsZero()
+    public function testGetNextWhenSurroundCountIsZero(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -140,7 +140,7 @@ public function testGetNextWhenSurroundCountIsZero()
         $this->assertSame('http://example.com/foo?foo=bar&page=5', $pager->getNext());
     }
 
-    public function testLinksBasics()
+    public function testLinksBasics(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -173,7 +173,7 @@ public function testLinksBasics()
         $this->assertSame($expected, $pager->links());
     }
 
-    public function testGetFirstAndGetLast()
+    public function testGetFirstAndGetLast(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -191,7 +191,7 @@ public function testGetFirstAndGetLast()
         $this->assertSame('http://example.com/foo?foo=bar&page=50', $pager->getLast());
     }
 
-    public function testGetCurrent()
+    public function testGetCurrent(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -208,7 +208,7 @@ public function testGetCurrent()
         $this->assertSame('http://example.com/foo?foo=bar&page=10', $pager->getCurrent());
     }
 
-    public function testGetCurrentWithSegment()
+    public function testGetCurrentWithSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -226,7 +226,7 @@ public function testGetCurrentWithSegment()
         $this->assertSame('http://example.com/foo/10?foo=bar', $pager->getCurrent());
     }
 
-    public function testSurroundCount()
+    public function testSurroundCount(): void
     {
         $uri = $this->uri;
 
@@ -259,7 +259,7 @@ public function testSurroundCount()
         $this->assertNull($pager->getNext());
     }
 
-    public function testHasPreviousReturnsFalseWhenFirstIsOneSegment()
+    public function testHasPreviousReturnsFalseWhenFirstIsOneSegment(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -274,7 +274,7 @@ public function testHasPreviousReturnsFalseWhenFirstIsOneSegment()
         $this->assertFalse($pager->hasPrevious());
     }
 
-    public function testHasPreviousReturnsTrueWhenFirstIsMoreThanOneSegment()
+    public function testHasPreviousReturnsTrueWhenFirstIsMoreThanOneSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -294,7 +294,7 @@ public function testHasPreviousReturnsTrueWhenFirstIsMoreThanOneSegment()
         $this->assertSame('http://example.com/foo/2?foo=bar', $pager->getPrevious());
     }
 
-    public function testGetPreviousWhenSurroundCountIsZeroSegment()
+    public function testGetPreviousWhenSurroundCountIsZeroSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -314,7 +314,7 @@ public function testGetPreviousWhenSurroundCountIsZeroSegment()
         $this->assertSame('http://example.com/foo/3?foo=bar', $pager->getPrevious());
     }
 
-    public function testHasNextReturnsFalseWhenLastIsTotalSegment()
+    public function testHasNextReturnsFalseWhenLastIsTotalSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -333,7 +333,7 @@ public function testHasNextReturnsFalseWhenLastIsTotalSegment()
         $this->assertFalse($pager->hasNext());
     }
 
-    public function testHasNextReturnsTrueWhenLastIsSmallerThanTotalSegment()
+    public function testHasNextReturnsTrueWhenLastIsSmallerThanTotalSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -353,7 +353,7 @@ public function testHasNextReturnsTrueWhenLastIsSmallerThanTotalSegment()
         $this->assertSame('http://example.com/foo/7?foo=bar', $pager->getNext());
     }
 
-    public function testGetNextWhenSurroundCountIsZeroSegment()
+    public function testGetNextWhenSurroundCountIsZeroSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -373,7 +373,7 @@ public function testGetNextWhenSurroundCountIsZeroSegment()
         $this->assertSame('http://example.com/foo/5?foo=bar', $pager->getNext());
     }
 
-    public function testLinksBasicsSegment()
+    public function testLinksBasicsSegment(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -407,7 +407,7 @@ public function testLinksBasicsSegment()
         $this->assertSame($expected, $pager->links());
     }
 
-    public function testGetFirstAndGetLastSegment()
+    public function testGetFirstAndGetLastSegment(): void
     {
         $uri = $this->uri;
         $uri->addQuery('foo', 'bar');
@@ -426,7 +426,7 @@ public function testGetFirstAndGetLastSegment()
         $this->assertSame('http://example.com/foo/50?foo=bar', $pager->getLast());
     }
 
-    public function testHasPreviousPageReturnsFalseWhenCurrentPageIsFirst()
+    public function testHasPreviousPageReturnsFalseWhenCurrentPageIsFirst(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -441,7 +441,7 @@ public function testHasPreviousPageReturnsFalseWhenCurrentPageIsFirst()
         $this->assertFalse($pager->hasPreviousPage());
     }
 
-    public function testHasNextPageReturnsFalseWhenCurrentPageIsLast()
+    public function testHasNextPageReturnsFalseWhenCurrentPageIsLast(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -456,7 +456,7 @@ public function testHasNextPageReturnsFalseWhenCurrentPageIsLast()
         $this->assertFalse($pager->hasNextPage());
     }
 
-    public function testHasPreviousPageReturnsTrueWhenFirstIsMoreThanCurrent()
+    public function testHasPreviousPageReturnsTrueWhenFirstIsMoreThanCurrent(): void
     {
         $uri = $this->uri;
 
@@ -474,7 +474,7 @@ public function testHasPreviousPageReturnsTrueWhenFirstIsMoreThanCurrent()
         $this->assertSame('http://example.com/foo?page=2', $pager->getPreviousPage());
     }
 
-    public function testGetPreviousPageWithSegmentHigherThanZero()
+    public function testGetPreviousPageWithSegmentHigherThanZero(): void
     {
         $uri = $this->uri;
 
@@ -490,7 +490,7 @@ public function testGetPreviousPageWithSegmentHigherThanZero()
         $this->assertSame('http://example.com/foo/2', $pager->getPreviousPage());
     }
 
-    public function testHasNextPageReturnsTrueWhenLastIsMoreThanCurrent()
+    public function testHasNextPageReturnsTrueWhenLastIsMoreThanCurrent(): void
     {
         $uri = $this->uri;
 
@@ -508,7 +508,7 @@ public function testHasNextPageReturnsTrueWhenLastIsMoreThanCurrent()
         $this->assertSame('http://example.com/foo?page=4', $pager->getNextPage());
     }
 
-    public function testGetNextPageWithSegmentHigherThanZero()
+    public function testGetNextPageWithSegmentHigherThanZero(): void
     {
         $uri = $this->uri;
 
@@ -524,7 +524,7 @@ public function testGetNextPageWithSegmentHigherThanZero()
         $this->assertSame('http://example.com/foo/4', $pager->getNextPage());
     }
 
-    public function testGetPageNumber()
+    public function testGetPageNumber(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -541,7 +541,7 @@ public function testGetPageNumber()
         $this->assertSame(10, $pager->getPageCount());
     }
 
-    public function testGetPageNumberSetSurroundCount()
+    public function testGetPageNumberSetSurroundCount(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -558,7 +558,7 @@ public function testGetPageNumberSetSurroundCount()
         $this->assertSame(7, $pager->getLastPageNumber());
     }
 
-    public function testGetPreviousPageNumber()
+    public function testGetPreviousPageNumber(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -573,7 +573,7 @@ public function testGetPreviousPageNumber()
         $this->assertSame(4, $pager->getPreviousPageNumber());
     }
 
-    public function testGetPreviousPageNumberNull()
+    public function testGetPreviousPageNumberNull(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -588,7 +588,7 @@ public function testGetPreviousPageNumberNull()
         $this->assertNull($pager->getPreviousPageNumber());
     }
 
-    public function testGetNextPageNumber()
+    public function testGetNextPageNumber(): void
     {
         $details = [
             'uri'         => $this->uri,
@@ -603,7 +603,7 @@ public function testGetNextPageNumber()
         $this->assertSame(6, $pager->getNextPageNumber());
     }
 
-    public function testGetNextPageNumberNull()
+    public function testGetNextPageNumberNull(): void
     {
         $details = [
             'uri'         => $this->uri,
diff --git a/tests/system/Pager/PagerTest.php b/tests/system/Pager/PagerTest.php
index 1c3861748b34..63ae20d3cd0c 100644
--- a/tests/system/Pager/PagerTest.php
+++ b/tests/system/Pager/PagerTest.php
@@ -64,7 +64,7 @@ private function createPager(string $requestUri): void
         $this->pager  = new Pager($this->config, Services::renderer());
     }
 
-    public function testSetPathRemembersPath()
+    public function testSetPathRemembersPath(): void
     {
         $this->pager->setPath('foo/bar');
 
@@ -73,7 +73,7 @@ public function testSetPathRemembersPath()
         $this->assertSame('foo/bar', $details['uri']->getPath());
     }
 
-    public function testGetDetailsRecognizesPageQueryVar()
+    public function testGetDetailsRecognizesPageQueryVar(): void
     {
         $_GET['page'] = 2;
 
@@ -85,7 +85,7 @@ public function testGetDetailsRecognizesPageQueryVar()
         $this->assertSame(2, $details['currentPage']);
     }
 
-    public function testGetDetailsRecognizesGroupedPageQueryVar()
+    public function testGetDetailsRecognizesGroupedPageQueryVar(): void
     {
         $_GET['page_foo'] = 2;
 
@@ -97,14 +97,14 @@ public function testGetDetailsRecognizesGroupedPageQueryVar()
         $this->assertSame(2, $details['currentPage']);
     }
 
-    public function testGetDetailsThrowExceptionIfGroupNotFound()
+    public function testGetDetailsThrowExceptionIfGroupNotFound(): void
     {
         $this->expectException(PagerException::class);
 
         $this->pager->getDetails('foo');
     }
 
-    public function testDetailsHasConfiguredPerPageValue()
+    public function testDetailsHasConfiguredPerPageValue(): void
     {
         // Need this to create the group.
         $this->pager->setPath('foo/bar', 'foo');
@@ -114,7 +114,7 @@ public function testDetailsHasConfiguredPerPageValue()
         $this->assertSame($this->config->perPage, $details['perPage']);
     }
 
-    public function testStoreDoesBasicCalcs()
+    public function testStoreDoesBasicCalcs(): void
     {
         $this->pager->store('foo', 3, 25, 100);
 
@@ -125,7 +125,7 @@ public function testStoreDoesBasicCalcs()
         $this->assertSame($details['currentPage'], 3);
     }
 
-    public function testStoreDoesBasicCalcsOnPerPageReadFromPagerConfig()
+    public function testStoreDoesBasicCalcsOnPerPageReadFromPagerConfig(): void
     {
         $this->pager->store('foo', 3, null, 100);
 
@@ -136,21 +136,21 @@ public function testStoreDoesBasicCalcsOnPerPageReadFromPagerConfig()
         $this->assertSame($details['currentPage'], 3);
     }
 
-    public function testStoreAndHasMore()
+    public function testStoreAndHasMore(): void
     {
         $this->pager->store('foo', 3, 25, 100);
 
         $this->assertTrue($this->pager->hasMore('foo'));
     }
 
-    public function testStoreAndHasMoreCanBeFalse()
+    public function testStoreAndHasMoreCanBeFalse(): void
     {
         $this->pager->store('foo', 3, 25, 70);
 
         $this->assertFalse($this->pager->hasMore('foo'));
     }
 
-    public function testStoreWithQueries()
+    public function testStoreWithQueries(): void
     {
         $_GET['page'] = 3;
         $_GET['foo']  = 'bar';
@@ -166,7 +166,7 @@ public function testStoreWithQueries()
         );
     }
 
-    public function testStoreWithSegments()
+    public function testStoreWithSegments(): void
     {
         $_GET['page'] = 3;
         $_GET['foo']  = 'bar';
@@ -182,7 +182,7 @@ public function testStoreWithSegments()
         );
     }
 
-    public function testGetPageURIWithURIReturnObject()
+    public function testGetPageURIWithURIReturnObject(): void
     {
         $this->pager->store('bar', 5, 25, 100, 1);
 
@@ -191,50 +191,50 @@ public function testGetPageURIWithURIReturnObject()
         $this->assertInstanceOf(URI::class, $uri);
     }
 
-    public function testHasMoreDefaultsToFalse()
+    public function testHasMoreDefaultsToFalse(): void
     {
         $this->assertFalse($this->pager->hasMore('foo'));
     }
 
-    public function testPerPageHasDefaultValue()
+    public function testPerPageHasDefaultValue(): void
     {
         $this->assertSame($this->config->perPage, $this->pager->getPerPage());
     }
 
-    public function testPerPageKeepsStoredValue()
+    public function testPerPageKeepsStoredValue(): void
     {
         $this->pager->store('foo', 3, 13, 70);
 
         $this->assertSame(13, $this->pager->getPerPage('foo'));
     }
 
-    public function testGetCurrentPageDefaultsToOne()
+    public function testGetCurrentPageDefaultsToOne(): void
     {
         $this->assertSame(1, $this->pager->getCurrentPage());
     }
 
-    public function testGetCurrentPageRemembersStoredPage()
+    public function testGetCurrentPageRemembersStoredPage(): void
     {
         $this->pager->store('foo', 3, 13, 70);
 
         $this->assertSame(3, $this->pager->getCurrentPage('foo'));
     }
 
-    public function testGetCurrentPageDetectsURI()
+    public function testGetCurrentPageDetectsURI(): void
     {
         $_GET['page'] = 2;
 
         $this->assertSame(2, $this->pager->getCurrentPage());
     }
 
-    public function testGetCurrentPageDetectsGroupedURI()
+    public function testGetCurrentPageDetectsGroupedURI(): void
     {
         $_GET['page_foo'] = 2;
 
         $this->assertSame(2, $this->pager->getCurrentPage('foo'));
     }
 
-    public function testGetCurrentPageFromSegment()
+    public function testGetCurrentPageFromSegment(): void
     {
         $this->createPager('/page/2');
 
@@ -244,26 +244,26 @@ public function testGetCurrentPageFromSegment()
         $this->assertSame(2, $this->pager->getCurrentPage());
     }
 
-    public function testGetTotalPagesDefaultsToOne()
+    public function testGetTotalPagesDefaultsToOne(): void
     {
         $this->assertSame(1, $this->pager->getPageCount());
     }
 
-    public function testGetTotalCorrectValue()
+    public function testGetTotalCorrectValue(): void
     {
         $this->pager->store('foo', 3, 12, 70);
 
         $this->assertSame(70, $this->pager->getTotal('foo'));
     }
 
-    public function testGetTotalPagesCalcsCorrectValue()
+    public function testGetTotalPagesCalcsCorrectValue(): void
     {
         $this->pager->store('foo', 3, 12, 70);
 
         $this->assertSame(6, $this->pager->getPageCount('foo'));
     }
 
-    public function testGetNextURIUsesCurrentURI()
+    public function testGetNextURIUsesCurrentURI(): void
     {
         $_GET['page_foo'] = 2;
 
@@ -275,14 +275,14 @@ public function testGetNextURIUsesCurrentURI()
         $this->assertSame($expected, $this->pager->getNextPageURI('foo'));
     }
 
-    public function testGetNextURIReturnsNullOnLastPage()
+    public function testGetNextURIReturnsNullOnLastPage(): void
     {
         $this->pager->store('foo', 6, 12, 70);
 
         $this->assertNull($this->pager->getNextPageURI('foo'));
     }
 
-    public function testGetNextURICorrectOnFirstPage()
+    public function testGetNextURICorrectOnFirstPage(): void
     {
         $this->pager->store('foo', 1, 12, 70);
 
@@ -292,7 +292,7 @@ public function testGetNextURICorrectOnFirstPage()
         $this->assertSame($expected, $this->pager->getNextPageURI('foo'));
     }
 
-    public function testGetPreviousURIUsesCurrentURI()
+    public function testGetPreviousURIUsesCurrentURI(): void
     {
         $_GET['page_foo'] = 2;
 
@@ -304,14 +304,14 @@ public function testGetPreviousURIUsesCurrentURI()
         $this->assertSame($expected, $this->pager->getPreviousPageURI('foo'));
     }
 
-    public function testGetNextURIReturnsNullOnFirstPage()
+    public function testGetNextURIReturnsNullOnFirstPage(): void
     {
         $this->pager->store('foo', 1, 12, 70);
 
         $this->assertNull($this->pager->getPreviousPageURI('foo'));
     }
 
-    public function testGetNextURIWithQueryStringUsesCurrentURI()
+    public function testGetNextURIWithQueryStringUsesCurrentURI(): void
     {
         $_GET = [
             'page_foo' => 3,
@@ -326,7 +326,7 @@ public function testGetNextURIWithQueryStringUsesCurrentURI()
         $this->assertSame($expected, $this->pager->getNextPageURI('foo'));
     }
 
-    public function testGetPreviousURIWithQueryStringUsesCurrentURI()
+    public function testGetPreviousURIWithQueryStringUsesCurrentURI(): void
     {
         $_GET = [
             'page_foo' => 1,
@@ -340,7 +340,7 @@ public function testGetPreviousURIWithQueryStringUsesCurrentURI()
         $this->assertSame($expected, $this->pager->getPreviousPageURI('foo'));
     }
 
-    public function testGetOnlyQueries()
+    public function testGetOnlyQueries(): void
     {
         $_GET = [
             'page'     => 2,
@@ -372,7 +372,7 @@ public function testGetOnlyQueries()
         );
     }
 
-    public function testBadTemplate()
+    public function testBadTemplate(): void
     {
         $this->expectException(PagerException::class);
         $this->pager->links('default', 'bogus');
@@ -381,17 +381,17 @@ public function testBadTemplate()
     // the tests below are looking for specific <ul> elements.
     // not the most rigorous, but a start :-/
 
-    public function testLinks()
+    public function testLinks(): void
     {
         $this->assertStringContainsString('<ul class="pagination">', $this->pager->links());
     }
 
-    public function testSimpleLinks()
+    public function testSimpleLinks(): void
     {
         $this->assertStringContainsString('<ul class="pager">', $this->pager->simpleLinks());
     }
 
-    public function testMakeLinks()
+    public function testMakeLinks(): void
     {
         $this->assertStringContainsString(
             '<ul class="pagination">',
@@ -439,7 +439,7 @@ public function testMakeLinks()
         );
     }
 
-    public function testHeadLinks()
+    public function testHeadLinks(): void
     {
         $firstPage = $this->pager->makeLinks(1, 10, 50, 'default_head');
 
@@ -460,7 +460,7 @@ public function testHeadLinks()
         $this->assertStringNotContainsString('<link rel="next"', $lastPage);
     }
 
-    public function testBasedURI()
+    public function testBasedURI(): void
     {
         $_SERVER['HTTP_HOST']   = 'example.com';
         $_SERVER['REQUEST_URI'] = '/ci/v4/x/y';
@@ -494,13 +494,13 @@ public function testBasedURI()
         $this->assertSame($expected, $this->pager->getPreviousPageURI('foo'));
     }
 
-    public function testAccessPageMoreThanPageCountGetLastPage()
+    public function testAccessPageMoreThanPageCountGetLastPage(): void
     {
         $this->pager->store('default', 11, 1, 10);
         $this->assertSame(10, $this->pager->getCurrentPage());
     }
 
-    public function testSegmentOutOfBound()
+    public function testSegmentOutOfBound(): void
     {
         $this->pager->store('default', 10, 1, 10, 1000);
         $this->assertSame(1, $this->pager->getCurrentPage());
diff --git a/tests/system/Publisher/PublisherContentReplaceTest.php b/tests/system/Publisher/PublisherContentReplaceTest.php
index bd15715b7b6c..da1b343fa335 100644
--- a/tests/system/Publisher/PublisherContentReplaceTest.php
+++ b/tests/system/Publisher/PublisherContentReplaceTest.php
@@ -40,7 +40,7 @@ protected function tearDown(): void
         unlink($this->file);
     }
 
-    public function testAddLineAfter()
+    public function testAddLineAfter(): void
     {
         $result = $this->publisher->addLineAfter(
             $this->file,
@@ -56,7 +56,7 @@ public function testAddLineAfter()
         );
     }
 
-    public function testAddLineBefore()
+    public function testAddLineBefore(): void
     {
         $result = $this->publisher->addLineBefore(
             $this->file,
@@ -72,7 +72,7 @@ public function testAddLineBefore()
         );
     }
 
-    public function testReplace()
+    public function testReplace(): void
     {
         $result = $this->publisher->replace(
             $this->file,
diff --git a/tests/system/Publisher/PublisherInputTest.php b/tests/system/Publisher/PublisherInputTest.php
index 1d9908fda041..fa8ce8091a03 100644
--- a/tests/system/Publisher/PublisherInputTest.php
+++ b/tests/system/Publisher/PublisherInputTest.php
@@ -42,7 +42,7 @@ public static function setUpBeforeClass(): void
         helper(['filesystem']);
     }
 
-    public function testAddPathFile()
+    public function testAddPathFile(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files');
 
@@ -51,7 +51,7 @@ public function testAddPathFile()
         $this->assertSame([$this->file], $publisher->get());
     }
 
-    public function testAddPathFileRecursiveDoesNothing()
+    public function testAddPathFileRecursiveDoesNothing(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files');
 
@@ -60,7 +60,7 @@ public function testAddPathFileRecursiveDoesNothing()
         $this->assertSame([$this->file], $publisher->get());
     }
 
-    public function testAddPathDirectory()
+    public function testAddPathDirectory(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files');
 
@@ -75,7 +75,7 @@ public function testAddPathDirectory()
         $this->assertSame($expected, $publisher->get());
     }
 
-    public function testAddPathDirectoryRecursive()
+    public function testAddPathDirectoryRecursive(): void
     {
         $publisher = new Publisher(SUPPORTPATH);
 
@@ -91,7 +91,7 @@ public function testAddPathDirectoryRecursive()
         $this->assertSame($expected, $publisher->get());
     }
 
-    public function testAddPaths()
+    public function testAddPaths(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files');
 
@@ -110,7 +110,7 @@ public function testAddPaths()
         $this->assertSame($expected, $publisher->get());
     }
 
-    public function testAddPathsRecursive()
+    public function testAddPathsRecursive(): void
     {
         $publisher = new Publisher(SUPPORTPATH);
 
@@ -130,7 +130,7 @@ public function testAddPathsRecursive()
         $this->assertSame($expected, $publisher->get());
     }
 
-    public function testAddUri()
+    public function testAddUri(): void
     {
         $publisher = new Publisher();
         $publisher->addUri('https://raw.githubusercontent.com/codeigniter4/CodeIgniter4/develop/composer.json');
@@ -140,7 +140,7 @@ public function testAddUri()
         $this->assertSame([$scratch . 'composer.json'], $publisher->get());
     }
 
-    public function testAddUris()
+    public function testAddUris(): void
     {
         $publisher = new Publisher();
         $publisher->addUris([
diff --git a/tests/system/Publisher/PublisherOutputTest.php b/tests/system/Publisher/PublisherOutputTest.php
index 0bf746ce9373..6e24a0971bdd 100644
--- a/tests/system/Publisher/PublisherOutputTest.php
+++ b/tests/system/Publisher/PublisherOutputTest.php
@@ -78,7 +78,7 @@ protected function setUp(): void
         config('Publisher')->restrictions[$this->root->url()] = '*';
     }
 
-    public function testCopy()
+    public function testCopy(): void
     {
         $publisher = new Publisher($this->directory, $this->root->url());
         $publisher->addFile($this->file);
@@ -91,7 +91,7 @@ public function testCopy()
         $this->assertFileExists($this->root->url() . '/banana.php');
     }
 
-    public function testCopyReplace()
+    public function testCopyReplace(): void
     {
         $file      = $this->directory . 'apple.php';
         $publisher = new Publisher($this->directory, $this->root->url() . '/able');
@@ -106,7 +106,7 @@ public function testCopyReplace()
         $this->assertTrue(same_file($file, $this->root->url() . '/able/apple.php'));
     }
 
-    public function testCopyIgnoresSame()
+    public function testCopyIgnoresSame(): void
     {
         $publisher = new Publisher($this->directory, $this->root->url());
         $publisher->addFile($this->file);
@@ -121,7 +121,7 @@ public function testCopyIgnoresSame()
         $this->assertSame([$this->root->url() . '/banana.php'], $publisher->getPublished());
     }
 
-    public function testCopyIgnoresCollision()
+    public function testCopyIgnoresCollision(): void
     {
         $publisher = new Publisher($this->directory, $this->root->url());
 
@@ -134,7 +134,7 @@ public function testCopyIgnoresCollision()
         $this->assertSame([$this->root->url() . '/banana.php'], $publisher->getPublished());
     }
 
-    public function testCopyCollides()
+    public function testCopyCollides(): void
     {
         $publisher = new Publisher($this->directory, $this->root->url());
         $expected  = lang('Publisher.collision', ['dir', $this->file, $this->root->url() . '/banana.php']);
@@ -151,7 +151,7 @@ public function testCopyCollides()
         $this->assertSame($expected, $errors[$this->file]->getMessage());
     }
 
-    public function testMerge()
+    public function testMerge(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files', $this->root->url());
         $expected  = [
@@ -172,7 +172,7 @@ public function testMerge()
         $this->assertSame($expected, $publisher->getPublished());
     }
 
-    public function testMergeReplace()
+    public function testMergeReplace(): void
     {
         $this->assertFalse(same_file($this->directory . 'apple.php', $this->root->url() . '/able/apple.php'));
         $publisher = new Publisher(SUPPORTPATH . 'Files', $this->root->url());
@@ -190,7 +190,7 @@ public function testMergeReplace()
         $this->assertSame($expected, $publisher->getPublished());
     }
 
-    public function testMergeCollides()
+    public function testMergeCollides(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files', $this->root->url());
         $expected  = lang('Publisher.collision', ['dir', $this->directory . 'fig_3.php', $this->root->url() . '/able/fig_3.php']);
@@ -212,7 +212,7 @@ public function testMergeCollides()
         $this->assertSame($expected, $errors[$this->directory . 'fig_3.php']->getMessage());
     }
 
-    public function testPublish()
+    public function testPublish(): void
     {
         $publisher = new Publisher(SUPPORTPATH . 'Files', $this->root->url());
 
diff --git a/tests/system/Publisher/PublisherRestrictionsTest.php b/tests/system/Publisher/PublisherRestrictionsTest.php
index f351a1791a73..ccecc704cd21 100644
--- a/tests/system/Publisher/PublisherRestrictionsTest.php
+++ b/tests/system/Publisher/PublisherRestrictionsTest.php
@@ -29,12 +29,12 @@ final class PublisherRestrictionsTest extends CIUnitTestCase
     /**
      * @see \Tests\Support\Config\Registrar::Publisher()
      */
-    public function testRegistrarsNotAllowed()
+    public function testRegistrarsNotAllowed(): void
     {
         $this->assertArrayNotHasKey(SUPPORTPATH, config('Publisher')->restrictions);
     }
 
-    public function testImmutableRestrictions()
+    public function testImmutableRestrictions(): void
     {
         $publisher = new Publisher();
 
@@ -49,7 +49,7 @@ public function testImmutableRestrictions()
     /**
      * @dataProvider fileProvider
      */
-    public function testDefaultPublicRestrictions(string $path)
+    public function testDefaultPublicRestrictions(string $path): void
     {
         $publisher = new Publisher(ROOTPATH, FCPATH);
         $pattern   = config('Publisher')->restrictions[FCPATH];
@@ -81,7 +81,7 @@ public function fileProvider(): iterable
     /**
      * @dataProvider destinationProvider
      */
-    public function testDestinations(string $destination, bool $allowed)
+    public function testDestinations(string $destination, bool $allowed): void
     {
         config('Publisher')->restrictions = [
             APPPATH                   => '',
diff --git a/tests/system/Publisher/PublisherSupportTest.php b/tests/system/Publisher/PublisherSupportTest.php
index 5ef05e274bb7..dfcab1b6bc88 100644
--- a/tests/system/Publisher/PublisherSupportTest.php
+++ b/tests/system/Publisher/PublisherSupportTest.php
@@ -44,7 +44,7 @@ public static function setUpBeforeClass(): void
         helper(['filesystem']);
     }
 
-    public function testDiscoverDefault()
+    public function testDiscoverDefault(): void
     {
         $result = Publisher::discover();
 
@@ -52,14 +52,14 @@ public function testDiscoverDefault()
         $this->assertInstanceOf(TestPublisher::class, $result[0]);
     }
 
-    public function testDiscoverNothing()
+    public function testDiscoverNothing(): void
     {
         $result = Publisher::discover('Nothing');
 
         $this->assertSame([], $result);
     }
 
-    public function testDiscoverStores()
+    public function testDiscoverStores(): void
     {
         $publisher = Publisher::discover()[0];
         $publisher->set([])->addFile($this->file);
@@ -69,21 +69,21 @@ public function testDiscoverStores()
         $this->assertSame([$this->file], $result[0]->get());
     }
 
-    public function testGetSource()
+    public function testGetSource(): void
     {
         $publisher = new Publisher(ROOTPATH);
 
         $this->assertSame(ROOTPATH, $publisher->getSource());
     }
 
-    public function testGetDestination()
+    public function testGetDestination(): void
     {
         $publisher = new Publisher(ROOTPATH, SUPPORTPATH);
 
         $this->assertSame(SUPPORTPATH, $publisher->getDestination());
     }
 
-    public function testGetScratch()
+    public function testGetScratch(): void
     {
         $publisher = new Publisher();
         $this->assertNull($this->getPrivateProperty($publisher, 'scratch'));
@@ -105,7 +105,7 @@ public function testGetScratch()
         $this->assertDirectoryDoesNotExist($scratch);
     }
 
-    public function testGetErrors()
+    public function testGetErrors(): void
     {
         $publisher = new Publisher();
         $this->assertSame([], $publisher->getErrors());
@@ -119,7 +119,7 @@ public function testGetErrors()
         $this->assertSame($expected, $publisher->getErrors());
     }
 
-    public function testWipeDirectory()
+    public function testWipeDirectory(): void
     {
         $directory = rtrim(sys_get_temp_dir(), DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR . bin2hex(random_bytes(6));
         mkdir($directory, 0700);
@@ -131,7 +131,7 @@ public function testWipeDirectory()
         $this->assertDirectoryDoesNotExist($directory);
     }
 
-    public function testWipeIgnoresFiles()
+    public function testWipeIgnoresFiles(): void
     {
         $method = $this->getPrivateMethodInvoker(Publisher::class, 'wipeDirectory');
         $method($this->file);
@@ -139,7 +139,7 @@ public function testWipeIgnoresFiles()
         $this->assertFileExists($this->file);
     }
 
-    public function testWipe()
+    public function testWipe(): void
     {
         $directory = rtrim(sys_get_temp_dir(), DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR . bin2hex(random_bytes(6));
         mkdir($directory, 0700);
diff --git a/tests/system/RESTful/ResourceControllerTest.php b/tests/system/RESTful/ResourceControllerTest.php
index fe1d0ac6f781..e45cc7c4fca4 100644
--- a/tests/system/RESTful/ResourceControllerTest.php
+++ b/tests/system/RESTful/ResourceControllerTest.php
@@ -85,7 +85,7 @@ protected function tearDown(): void
         }
     }
 
-    public function testResourceGet()
+    public function testResourceGet(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -106,7 +106,7 @@ public function testResourceGet()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['index']), $error);
     }
 
-    public function testResourceGetNew()
+    public function testResourceGetNew(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -128,7 +128,7 @@ public function testResourceGetNew()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['new']), $error);
     }
 
-    public function testResourceGetEdit()
+    public function testResourceGetEdit(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -151,7 +151,7 @@ public function testResourceGetEdit()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['edit']), $error);
     }
 
-    public function testResourceGetOne()
+    public function testResourceGetOne(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -173,7 +173,7 @@ public function testResourceGetOne()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['show']), $error);
     }
 
-    public function testResourcePost()
+    public function testResourcePost(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -194,7 +194,7 @@ public function testResourcePost()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['create']), $error);
     }
 
-    public function testResourcePatch()
+    public function testResourcePatch(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -216,7 +216,7 @@ public function testResourcePatch()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['update']), $error);
     }
 
-    public function testResourcePut()
+    public function testResourcePut(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -238,7 +238,7 @@ public function testResourcePut()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['update']), $error);
     }
 
-    public function testResourceDelete()
+    public function testResourceDelete(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -260,14 +260,14 @@ public function testResourceDelete()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['delete']), $error);
     }
 
-    public function testModel()
+    public function testModel(): void
     {
         $resource = new MockResourceController();
         $this->assertEmpty($resource->getModel());
         $this->assertEmpty($resource->getModelName());
     }
 
-    public function testModelBogus()
+    public function testModelBogus(): void
     {
         $resource = new MockResourceController();
 
@@ -276,7 +276,7 @@ public function testModelBogus()
         $this->assertSame('Something', $resource->getModelName());
     }
 
-    public function testModelByName()
+    public function testModelByName(): void
     {
         $resource = new MockResourceController();
         $resource->setModel(UserModel::class);
@@ -284,7 +284,7 @@ public function testModelByName()
         $this->assertSame(UserModel::class, $resource->getModelName());
     }
 
-    public function testModelByObject()
+    public function testModelByObject(): void
     {
         $resource = new MockResourceController();
         $model    = new UserModel();
@@ -295,7 +295,7 @@ public function testModelByObject()
         $this->assertSame(UserModel::class, $resource->getModelName());
     }
 
-    public function testFormat()
+    public function testFormat(): void
     {
         $resource = new MockResourceController();
         $this->assertSame('json', $resource->getFormat());
@@ -307,7 +307,7 @@ public function testFormat()
         $this->assertSame('xml', $resource->getFormat());
     }
 
-    public function testJSONFormatOutput()
+    public function testJSONFormatOutput(): void
     {
         $resource = new MockResourceController();
 
@@ -335,7 +335,7 @@ public function testJSONFormatOutput()
         $this->assertSame($expected, $result);
     }
 
-    public function testXMLFormatOutput()
+    public function testXMLFormatOutput(): void
     {
         $resource = new MockResourceController();
 
diff --git a/tests/system/RESTful/ResourcePresenterTest.php b/tests/system/RESTful/ResourcePresenterTest.php
index a430b527a580..a3e82b69c365 100644
--- a/tests/system/RESTful/ResourcePresenterTest.php
+++ b/tests/system/RESTful/ResourcePresenterTest.php
@@ -76,7 +76,7 @@ protected function tearDown(): void
         }
     }
 
-    public function testResourceGet()
+    public function testResourceGet(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -96,7 +96,7 @@ public function testResourceGet()
         $this->assertSame(lang('RESTful.notImplemented', ['index']), $output);
     }
 
-    public function testResourceShow()
+    public function testResourceShow(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -118,7 +118,7 @@ public function testResourceShow()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['show']), $output);
     }
 
-    public function testResourceNew()
+    public function testResourceNew(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -139,7 +139,7 @@ public function testResourceNew()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['new']), $output);
     }
 
-    public function testResourceCreate()
+    public function testResourceCreate(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -160,7 +160,7 @@ public function testResourceCreate()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['create']), $output);
     }
 
-    public function testResourceRemove()
+    public function testResourceRemove(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -182,7 +182,7 @@ public function testResourceRemove()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['remove']), $output);
     }
 
-    public function testResourceDelete()
+    public function testResourceDelete(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -204,7 +204,7 @@ public function testResourceDelete()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['delete']), $output);
     }
 
-    public function testResourceEdit()
+    public function testResourceEdit(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -227,7 +227,7 @@ public function testResourceEdit()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['edit']), $output);
     }
 
-    public function testResourceUpdate()
+    public function testResourceUpdate(): void
     {
         $_SERVER['argv'] = [
             'index.php',
@@ -249,14 +249,14 @@ public function testResourceUpdate()
         $this->assertStringContainsString(lang('RESTful.notImplemented', ['update']), $output);
     }
 
-    public function testModel()
+    public function testModel(): void
     {
         $resource = new MockResourcePresenter();
         $this->assertEmpty($resource->getModel());
         $this->assertEmpty($resource->getModelName());
     }
 
-    public function testModelBogus()
+    public function testModelBogus(): void
     {
         $resource = new MockResourcePresenter();
 
@@ -265,7 +265,7 @@ public function testModelBogus()
         $this->assertSame('Something', $resource->getModelName());
     }
 
-    public function testModelByName()
+    public function testModelByName(): void
     {
         $resource = new MockResourcePresenter();
         $resource->setModel(UserModel::class);
@@ -273,7 +273,7 @@ public function testModelByName()
         $this->assertSame(UserModel::class, $resource->getModelName());
     }
 
-    public function testModelByObject()
+    public function testModelByObject(): void
     {
         $resource = new MockResourcePresenter();
         $model    = new UserModel();
@@ -284,7 +284,7 @@ public function testModelByObject()
         $this->assertSame(UserModel::class, $resource->getModelName());
     }
 
-    public function testChangeSetModelByObject()
+    public function testChangeSetModelByObject(): void
     {
         $resource = new MockResourcePresenter();
         $resource->setModel(UserModel::class);
@@ -297,7 +297,7 @@ public function testChangeSetModelByObject()
         $this->assertSame(EntityModel::class, $resource->getModelName());
     }
 
-    public function testChangeSetModelByName()
+    public function testChangeSetModelByName(): void
     {
         $resource = new MockResourcePresenter();
         $resource->setModel(UserModel::class);
diff --git a/tests/system/Router/AutoRouterImprovedTest.php b/tests/system/Router/AutoRouterImprovedTest.php
index 5b2fdff532c1..293e49441f4d 100644
--- a/tests/system/Router/AutoRouterImprovedTest.php
+++ b/tests/system/Router/AutoRouterImprovedTest.php
@@ -50,7 +50,7 @@ private function createNewAutoRouter(string $httpVerb = 'get'): AutoRouterImprov
         );
     }
 
-    public function testAutoRouteFindsDefaultControllerAndMethodGet()
+    public function testAutoRouteFindsDefaultControllerAndMethodGet(): void
     {
         $this->collection->setDefaultController('Index');
 
@@ -65,7 +65,7 @@ public function testAutoRouteFindsDefaultControllerAndMethodGet()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsDefaultControllerAndMethodPost()
+    public function testAutoRouteFindsDefaultControllerAndMethodPost(): void
     {
         $this->collection->setDefaultController('Index');
 
@@ -80,7 +80,7 @@ public function testAutoRouteFindsDefaultControllerAndMethodPost()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsControllerWithFileAndMethod()
+    public function testAutoRouteFindsControllerWithFileAndMethod(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -93,7 +93,7 @@ public function testAutoRouteFindsControllerWithFileAndMethod()
         $this->assertSame([], $params);
     }
 
-    public function testFindsControllerAndMethodAndParam()
+    public function testFindsControllerAndMethodAndParam(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -106,7 +106,7 @@ public function testFindsControllerAndMethodAndParam()
         $this->assertSame(['a'], $params);
     }
 
-    public function testUriParamCountIsGreaterThanMethodParams()
+    public function testUriParamCountIsGreaterThanMethodParams(): void
     {
         $this->expectException(PageNotFoundException::class);
         $this->expectExceptionMessage(
@@ -118,7 +118,7 @@ public function testUriParamCountIsGreaterThanMethodParams()
         $router->getRoute('mycontroller/somemethod/a/b', 'get');
     }
 
-    public function testAutoRouteFindsControllerWithFile()
+    public function testAutoRouteFindsControllerWithFile(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -131,7 +131,7 @@ public function testAutoRouteFindsControllerWithFile()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsControllerWithSubfolder()
+    public function testAutoRouteFindsControllerWithSubfolder(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -144,7 +144,7 @@ public function testAutoRouteFindsControllerWithSubfolder()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsDashedSubfolder()
+    public function testAutoRouteFindsDashedSubfolder(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -160,7 +160,7 @@ public function testAutoRouteFindsDashedSubfolder()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsDashedController()
+    public function testAutoRouteFindsDashedController(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -173,7 +173,7 @@ public function testAutoRouteFindsDashedController()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsDashedMethod()
+    public function testAutoRouteFindsDashedMethod(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -186,7 +186,7 @@ public function testAutoRouteFindsDashedMethod()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteFindsDefaultDashFolder()
+    public function testAutoRouteFindsDefaultDashFolder(): void
     {
         $router = $this->createNewAutoRouter();
 
@@ -199,7 +199,7 @@ public function testAutoRouteFindsDefaultDashFolder()
         $this->assertSame([], $params);
     }
 
-    public function testAutoRouteRejectsSingleDot()
+    public function testAutoRouteRejectsSingleDot(): void
     {
         $this->expectException(PageNotFoundException::class);
 
@@ -208,7 +208,7 @@ public function testAutoRouteRejectsSingleDot()
         $router->getRoute('.', 'get');
     }
 
-    public function testAutoRouteRejectsDoubleDot()
+    public function testAutoRouteRejectsDoubleDot(): void
     {
         $this->expectException(PageNotFoundException::class);
 
@@ -217,7 +217,7 @@ public function testAutoRouteRejectsDoubleDot()
         $router->getRoute('..', 'get');
     }
 
-    public function testAutoRouteRejectsMidDot()
+    public function testAutoRouteRejectsMidDot(): void
     {
         $this->expectException(PageNotFoundException::class);
 
@@ -226,7 +226,7 @@ public function testAutoRouteRejectsMidDot()
         $router->getRoute('foo.bar', 'get');
     }
 
-    public function testRejectsDefaultControllerPath()
+    public function testRejectsDefaultControllerPath(): void
     {
         $this->expectException(PageNotFoundException::class);
 
@@ -235,7 +235,7 @@ public function testRejectsDefaultControllerPath()
         $router->getRoute('home', 'get');
     }
 
-    public function testRejectsDefaultControllerAndDefaultMethodPath()
+    public function testRejectsDefaultControllerAndDefaultMethodPath(): void
     {
         $this->expectException(PageNotFoundException::class);
 
@@ -244,7 +244,7 @@ public function testRejectsDefaultControllerAndDefaultMethodPath()
         $router->getRoute('home/index', 'get');
     }
 
-    public function testRejectsDefaultMethodPath()
+    public function testRejectsDefaultMethodPath(): void
     {
         $this->expectException(PageNotFoundException::class);
 
@@ -253,7 +253,7 @@ public function testRejectsDefaultMethodPath()
         $router->getRoute('mycontroller/index', 'get');
     }
 
-    public function testRejectsControllerWithRemapMethod()
+    public function testRejectsControllerWithRemapMethod(): void
     {
         $this->expectException(PageNotFoundException::class);
         $this->expectExceptionMessage(
diff --git a/tests/system/Router/Controllers/Dash_folder/Dash_controller.php b/tests/system/Router/Controllers/Dash_folder/Dash_controller.php
index 52736f751b2f..2c608a9af1e1 100644
--- a/tests/system/Router/Controllers/Dash_folder/Dash_controller.php
+++ b/tests/system/Router/Controllers/Dash_folder/Dash_controller.php
@@ -15,11 +15,11 @@
 
 class Dash_controller extends Controller
 {
-    public function getSomemethod()
+    public function getSomemethod(): void
     {
     }
 
-    public function getDash_method()
+    public function getDash_method(): void
     {
     }
 }
diff --git a/tests/system/Router/Controllers/Dash_folder/Home.php b/tests/system/Router/Controllers/Dash_folder/Home.php
index 60ca6ce6c853..4406349c91b3 100644
--- a/tests/system/Router/Controllers/Dash_folder/Home.php
+++ b/tests/system/Router/Controllers/Dash_folder/Home.php
@@ -15,7 +15,7 @@
 
 class Home extends Controller
 {
-    public function getIndex()
+    public function getIndex(): void
     {
     }
 }
diff --git a/tests/system/Router/Controllers/Dash_folder/Mycontroller.php b/tests/system/Router/Controllers/Dash_folder/Mycontroller.php
index a5d5ba65fc6a..0dd70782182a 100644
--- a/tests/system/Router/Controllers/Dash_folder/Mycontroller.php
+++ b/tests/system/Router/Controllers/Dash_folder/Mycontroller.php
@@ -15,7 +15,7 @@
 
 class Mycontroller extends Controller
 {
-    public function getSomemethod()
+    public function getSomemethod(): void
     {
     }
 }
diff --git a/tests/system/Router/Controllers/Home.php b/tests/system/Router/Controllers/Home.php
index e4411e4ae592..ddb844e8cb78 100644
--- a/tests/system/Router/Controllers/Home.php
+++ b/tests/system/Router/Controllers/Home.php
@@ -15,11 +15,11 @@
 
 class Home extends Controller
 {
-    public function getIndex()
+    public function getIndex(): void
     {
     }
 
-    public function postIndex()
+    public function postIndex(): void
     {
     }
 }
diff --git a/tests/system/Router/Controllers/Index.php b/tests/system/Router/Controllers/Index.php
index bfc3539e0b1f..b2be979fe8a4 100644
--- a/tests/system/Router/Controllers/Index.php
+++ b/tests/system/Router/Controllers/Index.php
@@ -15,11 +15,11 @@
 
 class Index extends Controller
 {
-    public function getIndex()
+    public function getIndex(): void
     {
     }
 
-    public function postIndex()
+    public function postIndex(): void
     {
     }
 }
diff --git a/tests/system/Router/Controllers/Mycontroller.php b/tests/system/Router/Controllers/Mycontroller.php
index dc7f72a21dc5..b66a28f7ff6c 100644
--- a/tests/system/Router/Controllers/Mycontroller.php
+++ b/tests/system/Router/Controllers/Mycontroller.php
@@ -15,11 +15,11 @@
 
 class Mycontroller extends Controller
 {
-    public function getIndex()
+    public function getIndex(): void
     {
     }
 
-    public function getSomemethod($first = '')
+    public function getSomemethod($first = ''): void
     {
     }
 }
diff --git a/tests/system/Router/Controllers/Subfolder/Mycontroller.php b/tests/system/Router/Controllers/Subfolder/Mycontroller.php
index 9ab632a0fd98..0124c7ac33ec 100644
--- a/tests/system/Router/Controllers/Subfolder/Mycontroller.php
+++ b/tests/system/Router/Controllers/Subfolder/Mycontroller.php
@@ -15,7 +15,7 @@
 
 class Mycontroller extends Controller
 {
-    public function getSomemethod()
+    public function getSomemethod(): void
     {
     }
 }
diff --git a/tests/system/Router/RouteCollectionReverseRouteTest.php b/tests/system/Router/RouteCollectionReverseRouteTest.php
index 4f0e37c94c82..64ddacd163bb 100644
--- a/tests/system/Router/RouteCollectionReverseRouteTest.php
+++ b/tests/system/Router/RouteCollectionReverseRouteTest.php
@@ -51,7 +51,7 @@ protected function getCollector(array $config = [], array $files = [], $moduleCo
         return (new RouteCollection($loader, $moduleConfig))->setHTTPVerb('get');
     }
 
-    public function testReverseRoutingFindsSimpleMatch()
+    public function testReverseRoutingFindsSimpleMatch(): void
     {
         $routes = $this->getCollector();
 
@@ -64,7 +64,7 @@ public function testReverseRoutingFindsSimpleMatch()
         $this->assertSame('/path/string/to/13', $match);
     }
 
-    public function testReverseRoutingWithLocaleAndFindsSimpleMatch()
+    public function testReverseRoutingWithLocaleAndFindsSimpleMatch(): void
     {
         $routes = $this->getCollector();
 
@@ -77,7 +77,7 @@ public function testReverseRoutingWithLocaleAndFindsSimpleMatch()
         $this->assertSame('/en/path/string/to/13', $match);
     }
 
-    public function testReverseRoutingReturnsFalseWithBadParamCount()
+    public function testReverseRoutingReturnsFalseWithBadParamCount(): void
     {
         $routes = $this->getCollector();
 
@@ -88,7 +88,7 @@ public function testReverseRoutingReturnsFalseWithBadParamCount()
         $this->assertFalse($routes->reverseRoute('myController::goto', 'string', 13));
     }
 
-    public function testReverseRoutingReturnsFalseWithNoMatch()
+    public function testReverseRoutingReturnsFalseWithNoMatch(): void
     {
         $routes = $this->getCollector();
 
@@ -99,7 +99,7 @@ public function testReverseRoutingReturnsFalseWithNoMatch()
         $this->assertFalse($routes->reverseRoute('myBadController::goto', 'string', 13));
     }
 
-    public function testReverseRoutingThrowsExceptionWithBadParamTypes()
+    public function testReverseRoutingThrowsExceptionWithBadParamTypes(): void
     {
         $routes = $this->getCollector();
 
@@ -111,7 +111,7 @@ public function testReverseRoutingThrowsExceptionWithBadParamTypes()
         $routes->reverseRoute('myController::goto', 13, 'string');
     }
 
-    public function testReverseRoutingWithLocale()
+    public function testReverseRoutingWithLocale(): void
     {
         $routes = $this->getCollector();
 
@@ -132,7 +132,7 @@ public function reverseRoutingHandlerProvider(): iterable
     /**
      * @dataProvider reverseRoutingHandlerProvider
      */
-    public function testReverseRoutingDefaultNamespaceAppController(string $controller)
+    public function testReverseRoutingDefaultNamespaceAppController(string $controller): void
     {
         $routes = $this->getCollector();
         $routes->setDefaultNamespace('App\Controllers');
@@ -144,7 +144,7 @@ public function testReverseRoutingDefaultNamespaceAppController(string $controll
         $this->assertSame('/users/15/gallery12', $match);
     }
 
-    public function testReverseRoutingDefaultNamespaceAppControllerSubNamespace()
+    public function testReverseRoutingDefaultNamespaceAppControllerSubNamespace(): void
     {
         $routes = $this->getCollector();
         $routes->setDefaultNamespace('App\Controllers');
@@ -156,7 +156,7 @@ public function testReverseRoutingDefaultNamespaceAppControllerSubNamespace()
         $this->assertSame('/admin/15/gallery12', $match);
     }
 
-    public function testReverseRouteMatching()
+    public function testReverseRouteMatching(): void
     {
         $routes = $this->getCollector();
 
@@ -167,7 +167,7 @@ public function testReverseRouteMatching()
         $this->assertSame('/test/1/2', $match);
     }
 
-    public function testReverseRouteMatchingWithLocale()
+    public function testReverseRouteMatchingWithLocale(): void
     {
         $routes = $this->getCollector();
 
@@ -181,11 +181,11 @@ public function testReverseRouteMatchingWithLocale()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/568
      */
-    public function testReverseRoutingWithClosure()
+    public function testReverseRoutingWithClosure(): void
     {
         $routes = $this->getCollector();
 
-        $routes->add('login', static function () {
+        $routes->add('login', static function (): void {
         });
 
         $match = $routes->reverseRoute('login');
@@ -193,11 +193,11 @@ public function testReverseRoutingWithClosure()
         $this->assertSame('/login', $match);
     }
 
-    public function testReverseRoutingWithClosureNoMatch()
+    public function testReverseRoutingWithClosureNoMatch(): void
     {
         $routes = $this->getCollector();
 
-        $routes->add('login', static function () {
+        $routes->add('login', static function (): void {
         });
 
         $this->assertFalse($routes->reverseRoute('foobar'));
diff --git a/tests/system/Router/RouteCollectionTest.php b/tests/system/Router/RouteCollectionTest.php
index 734420f73733..4143c6a3bd2f 100644
--- a/tests/system/Router/RouteCollectionTest.php
+++ b/tests/system/Router/RouteCollectionTest.php
@@ -53,7 +53,7 @@ protected function getCollector(array $config = [], array $files = [], $moduleCo
         return (new RouteCollection($loader, $moduleConfig))->setHTTPVerb('get');
     }
 
-    public function testBasicAdd()
+    public function testBasicAdd(): void
     {
         $routes = $this->getCollector();
 
@@ -68,7 +68,7 @@ public function testBasicAdd()
         $this->assertSame($expects, $routes);
     }
 
-    public function testBasicAddCallable()
+    public function testBasicAddCallable(): void
     {
         $routes = $this->getCollector();
 
@@ -81,7 +81,7 @@ public function testBasicAddCallable()
         $this->assertSame($expects, $routes);
     }
 
-    public function testBasicAddCallableWithParamsString()
+    public function testBasicAddCallableWithParamsString(): void
     {
         $routes = $this->getCollector();
 
@@ -94,7 +94,7 @@ public function testBasicAddCallableWithParamsString()
         $this->assertSame($expects, $routes);
     }
 
-    public function testBasicAddCallableWithParamsWithoutString()
+    public function testBasicAddCallableWithParamsWithoutString(): void
     {
         $routes = $this->getCollector();
 
@@ -107,7 +107,7 @@ public function testBasicAddCallableWithParamsWithoutString()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddPrefixesDefaultNamespaceWhenNoneExist()
+    public function testAddPrefixesDefaultNamespaceWhenNoneExist(): void
     {
         $routes = $this->getCollector();
 
@@ -122,7 +122,7 @@ public function testAddPrefixesDefaultNamespaceWhenNoneExist()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddIgnoresDefaultNamespaceWhenExists()
+    public function testAddIgnoresDefaultNamespaceWhenExists(): void
     {
         $routes = $this->getCollector();
 
@@ -137,7 +137,7 @@ public function testAddIgnoresDefaultNamespaceWhenExists()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddWorksWithCurrentHTTPMethods()
+    public function testAddWorksWithCurrentHTTPMethods(): void
     {
         Services::request()->setMethod('get');
 
@@ -154,7 +154,7 @@ public function testAddWorksWithCurrentHTTPMethods()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddWithLeadingSlash()
+    public function testAddWithLeadingSlash(): void
     {
         $routes = $this->getCollector();
 
@@ -169,7 +169,7 @@ public function testAddWithLeadingSlash()
         $this->assertSame($expects, $routes);
     }
 
-    public function testMatchIgnoresInvalidHTTPMethods()
+    public function testMatchIgnoresInvalidHTTPMethods(): void
     {
         Services::request()->setMethod('get');
 
@@ -182,7 +182,7 @@ public function testMatchIgnoresInvalidHTTPMethods()
         $this->assertSame([], $routes);
     }
 
-    public function testAddWorksWithArrayOFHTTPMethods()
+    public function testAddWorksWithArrayOFHTTPMethods(): void
     {
         Services::request()->setMethod('post');
 
@@ -199,7 +199,7 @@ public function testAddWorksWithArrayOFHTTPMethods()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddReplacesDefaultPlaceholders()
+    public function testAddReplacesDefaultPlaceholders(): void
     {
         $routes = $this->getCollector();
 
@@ -214,7 +214,7 @@ public function testAddReplacesDefaultPlaceholders()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddReplacesCustomPlaceholders()
+    public function testAddReplacesCustomPlaceholders(): void
     {
         $routes = $this->getCollector();
         $routes->addPlaceholder('smiley', ':-)');
@@ -230,7 +230,7 @@ public function testAddReplacesCustomPlaceholders()
         $this->assertSame($expects, $routes);
     }
 
-    public function testAddRecognizesCustomNamespaces()
+    public function testAddRecognizesCustomNamespaces(): void
     {
         $routes = $this->getCollector();
         $routes->setDefaultNamespace('\CodeIgniter');
@@ -246,7 +246,7 @@ public function testAddRecognizesCustomNamespaces()
         $this->assertSame($expects, $routes);
     }
 
-    public function testSetDefaultControllerStoresIt()
+    public function testSetDefaultControllerStoresIt(): void
     {
         $routes = $this->getCollector();
         $routes->setDefaultController('godzilla');
@@ -254,7 +254,7 @@ public function testSetDefaultControllerStoresIt()
         $this->assertSame('godzilla', $routes->getDefaultController());
     }
 
-    public function testSetDefaultMethodStoresIt()
+    public function testSetDefaultMethodStoresIt(): void
     {
         $routes = $this->getCollector();
         $routes->setDefaultMethod('biggerBox');
@@ -262,7 +262,7 @@ public function testSetDefaultMethodStoresIt()
         $this->assertSame('biggerBox', $routes->getDefaultMethod());
     }
 
-    public function testTranslateURIDashesWorks()
+    public function testTranslateURIDashesWorks(): void
     {
         $routes = $this->getCollector();
         $routes->setTranslateURIDashes(true);
@@ -270,7 +270,7 @@ public function testTranslateURIDashesWorks()
         $this->assertTrue($routes->shouldTranslateURIDashes());
     }
 
-    public function testAutoRouteStoresIt()
+    public function testAutoRouteStoresIt(): void
     {
         $routes = $this->getCollector();
         $routes->setAutoRoute(true);
@@ -278,13 +278,13 @@ public function testAutoRouteStoresIt()
         $this->assertTrue($routes->shouldAutoRoute());
     }
 
-    public function testGroupingWorks()
+    public function testGroupingWorks(): void
     {
         $routes = $this->getCollector();
 
         $routes->group(
             'admin',
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->add('users/list', '\Users::list');
             }
         );
@@ -296,13 +296,13 @@ static function ($routes) {
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testGroupGetsSanitized()
+    public function testGroupGetsSanitized(): void
     {
         $routes = $this->getCollector();
 
         $routes->group(
             '<script>admin',
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->add('users/list', '\Users::list');
             }
         );
@@ -314,14 +314,14 @@ static function ($routes) {
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testGroupSetsOptions()
+    public function testGroupSetsOptions(): void
     {
         $routes = $this->getCollector();
 
         $routes->group(
             'admin',
             ['namespace' => 'Admin'],
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->add('users/list', 'Users::list');
             }
         );
@@ -333,13 +333,13 @@ static function ($routes) {
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testGroupingWorksWithEmptyStringPrefix()
+    public function testGroupingWorksWithEmptyStringPrefix(): void
     {
         $routes = $this->getCollector();
 
         $routes->group(
             '',
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->add('users/list', '\Users::list');
             }
         );
@@ -351,19 +351,19 @@ static function ($routes) {
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testNestedGroupingWorksWithEmptyPrefix()
+    public function testNestedGroupingWorksWithEmptyPrefix(): void
     {
         $routes = $this->getCollector();
 
         $routes->add('verify/begin', '\VerifyController::begin');
 
-        $routes->group('admin', static function ($routes) {
+        $routes->group('admin', static function ($routes): void {
             $routes->group(
                 '',
-                static function ($routes) {
+                static function ($routes): void {
                     $routes->add('users/list', '\Users::list');
 
-                    $routes->group('delegate', static function ($routes) {
+                    $routes->group('delegate', static function ($routes): void {
                         $routes->add('foo', '\Users::foo');
                     });
                 }
@@ -386,16 +386,16 @@ public function testNestedGroupingWorksWithRootPrefix(
         string $group,
         string $subgroup,
         array $expected
-    ) {
+    ): void {
         $routes = $this->getCollector();
 
-        $routes->group($group, static function ($routes) use ($subgroup) {
+        $routes->group($group, static function ($routes) use ($subgroup): void {
             $routes->group(
                 $subgroup,
-                static function ($routes) {
+                static function ($routes): void {
                     $routes->add('users/list', '\Users::list');
 
-                    $routes->group('delegate', static function ($routes) {
+                    $routes->group('delegate', static function ($routes): void {
                         $routes->add('foo', '\Users::foo');
                     });
                 }
@@ -427,7 +427,7 @@ public function groupProvider(): iterable
         ];
     }
 
-    public function testHostnameOption()
+    public function testHostnameOption(): void
     {
         $_SERVER['HTTP_HOST'] = 'example.com';
 
@@ -443,7 +443,7 @@ public function testHostnameOption()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourceScaffoldsCorrectly()
+    public function testResourceScaffoldsCorrectly(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('get');
@@ -502,7 +502,7 @@ public function testResourceScaffoldsCorrectly()
 
     // Similar to the above, but with a more typical endpoint
 
-    public function testResourceAPIScaffoldsCorrectly()
+    public function testResourceAPIScaffoldsCorrectly(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('get');
@@ -559,7 +559,7 @@ public function testResourceAPIScaffoldsCorrectly()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testPresenterScaffoldsCorrectly()
+    public function testPresenterScaffoldsCorrectly(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('get');
@@ -591,7 +591,7 @@ public function testPresenterScaffoldsCorrectly()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithCustomController()
+    public function testResourcesWithCustomController(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -608,7 +608,7 @@ public function testResourcesWithCustomController()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithCustomPlaceholder()
+    public function testResourcesWithCustomPlaceholder(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -625,7 +625,7 @@ public function testResourcesWithCustomPlaceholder()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithDefaultPlaceholder()
+    public function testResourcesWithDefaultPlaceholder(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -643,7 +643,7 @@ public function testResourcesWithDefaultPlaceholder()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithBogusDefaultPlaceholder()
+    public function testResourcesWithBogusDefaultPlaceholder(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -661,7 +661,7 @@ public function testResourcesWithBogusDefaultPlaceholder()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithOnly()
+    public function testResourcesWithOnly(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -675,7 +675,7 @@ public function testResourcesWithOnly()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithExcept()
+    public function testResourcesWithExcept(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -690,7 +690,7 @@ public function testResourcesWithExcept()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testResourcesWithWebsafe()
+    public function testResourcesWithWebsafe(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('post');
@@ -706,7 +706,7 @@ public function testResourcesWithWebsafe()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testMatchSupportsMultipleMethods()
+    public function testMatchSupportsMultipleMethods(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -722,7 +722,7 @@ public function testMatchSupportsMultipleMethods()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testGet()
+    public function testGet(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -733,7 +733,7 @@ public function testGet()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testPost()
+    public function testPost(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('post');
@@ -744,7 +744,7 @@ public function testPost()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testGetDoesntAllowOtherMethods()
+    public function testGetDoesntAllowOtherMethods(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('get');
@@ -756,7 +756,7 @@ public function testGetDoesntAllowOtherMethods()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testPut()
+    public function testPut(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('put');
@@ -767,7 +767,7 @@ public function testPut()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('delete');
@@ -778,7 +778,7 @@ public function testDelete()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testHead()
+    public function testHead(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('head');
@@ -789,7 +789,7 @@ public function testHead()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testPatch()
+    public function testPatch(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('patch');
@@ -800,7 +800,7 @@ public function testPatch()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testOptions()
+    public function testOptions(): void
     {
         $routes = $this->getCollector();
         $routes->setHTTPVerb('options');
@@ -811,7 +811,7 @@ public function testOptions()
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testCLI()
+    public function testCLI(): void
     {
         $routes = $this->getCollector();
 
@@ -821,7 +821,7 @@ public function testCLI()
         $this->assertSame($expected, $routes->getRoutes('cli'));
     }
 
-    public function testView()
+    public function testView(): void
     {
         $routes = $this->getCollector();
 
@@ -842,7 +842,7 @@ public function testView()
         $this->assertArrayNotHasKey('here', $routes->getRoutes('cli'));
     }
 
-    public function testEnvironmentRestricts()
+    public function testEnvironmentRestricts(): void
     {
         // ENVIRONMENT should be 'testing'
 
@@ -853,14 +853,14 @@ public function testEnvironmentRestricts()
 
         $routes->environment(
             'testing',
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->get('here', 'there');
             }
         );
 
         $routes->environment(
             'badenvironment',
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->get('from', 'to');
             }
         );
@@ -868,7 +868,7 @@ static function ($routes) {
         $this->assertSame($expected, $routes->getRoutes());
     }
 
-    public function testNamedRoutes()
+    public function testNamedRoutes(): void
     {
         $routes = $this->getCollector();
 
@@ -877,7 +877,7 @@ public function testNamedRoutes()
         $this->assertSame('/users', $routes->reverseRoute('namedRoute'));
     }
 
-    public function testNamedRoutesWithLocale()
+    public function testNamedRoutesWithLocale(): void
     {
         $routes = $this->getCollector();
 
@@ -886,7 +886,7 @@ public function testNamedRoutesWithLocale()
         $this->assertSame('/en/users', $routes->reverseRoute('namedRoute'));
     }
 
-    public function testNamedRoutesFillInParams()
+    public function testNamedRoutesFillInParams(): void
     {
         $routes = $this->getCollector();
 
@@ -899,7 +899,7 @@ public function testNamedRoutesFillInParams()
         $this->assertSame('/path/string/to/13', $match);
     }
 
-    public function testNamedRoutesWithLocaleAndFillInParams()
+    public function testNamedRoutesWithLocaleAndFillInParams(): void
     {
         $routes = $this->getCollector();
 
@@ -915,19 +915,19 @@ public function testNamedRoutesWithLocaleAndFillInParams()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/642
      */
-    public function testNamedRoutesWithSameURIDifferentMethods()
+    public function testNamedRoutesWithSameURIDifferentMethods(): void
     {
         $routes = $this->getCollector();
 
         $routes->get('user/insert', 'myController::goto/$1/$2', ['as' => 'namedRoute1']);
         $routes->post(
             'user/insert',
-            static function () {},
+            static function (): void {},
             ['as' => 'namedRoute2']
         );
         $routes->put(
             'user/insert',
-            static function () {},
+            static function (): void {},
             ['as' => 'namedRoute3']
         );
 
@@ -943,20 +943,20 @@ static function () {},
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/642
      */
-    public function testNamedRoutesWithLocaleAndWithSameURIDifferentMethods()
+    public function testNamedRoutesWithLocaleAndWithSameURIDifferentMethods(): void
     {
         $routes = $this->getCollector();
 
         $routes->get('{locale}/user/insert', 'myController::goto/$1/$2', ['as' => 'namedRoute1']);
         $routes->post(
             '{locale}/user/insert',
-            static function () {
+            static function (): void {
             },
             ['as' => 'namedRoute2']
         );
         $routes->put(
             '{locale}/user/insert',
-            static function () {
+            static function (): void {
             },
             ['as' => 'namedRoute3']
         );
@@ -973,7 +973,7 @@ static function () {
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3048
      */
-    public function testNamedRoutesWithPipesInRegex()
+    public function testNamedRoutesWithPipesInRegex(): void
     {
         $routes = $this->getCollector();
 
@@ -983,7 +983,7 @@ public function testNamedRoutesWithPipesInRegex()
         $this->assertSame('/system/that', $routes->reverseRoute('pipedRoute', 'that'));
     }
 
-    public function testAddRedirect()
+    public function testAddRedirect(): void
     {
         $routes = $this->getCollector();
 
@@ -1000,7 +1000,7 @@ public function testAddRedirect()
         $this->assertSame(0, $routes->getRedirectCode('bosses'));
     }
 
-    public function testAddRedirectNamed()
+    public function testAddRedirectNamed(): void
     {
         $routes = $this->getCollector();
 
@@ -1017,7 +1017,7 @@ public function testAddRedirectNamed()
         $this->assertSame(307, $routes->getRedirectCode('users'));
     }
 
-    public function testAddRedirectGetMethod()
+    public function testAddRedirectGetMethod(): void
     {
         $routes = $this->getCollector();
 
@@ -1037,7 +1037,7 @@ public function testAddRedirectGetMethod()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/497
      */
-    public function testWithSubdomain()
+    public function testWithSubdomain(): void
     {
         $_SERVER['HTTP_HOST'] = 'adm.example.com';
 
@@ -1052,7 +1052,7 @@ public function testWithSubdomain()
         $this->assertSame($expects, $routes->getRoutes());
     }
 
-    public function testWithSubdomainMissing()
+    public function testWithSubdomainMissing(): void
     {
         $_SERVER['HTTP_HOST'] = 'www.example.com';
 
@@ -1067,7 +1067,7 @@ public function testWithSubdomainMissing()
         $this->assertSame($expects, $routes->getRoutes());
     }
 
-    public function testWithDifferentSubdomain()
+    public function testWithDifferentSubdomain(): void
     {
         $_SERVER['HTTP_HOST'] = 'adm.example.com';
 
@@ -1082,7 +1082,7 @@ public function testWithDifferentSubdomain()
         $this->assertSame($expects, $routes->getRoutes());
     }
 
-    public function testWithWWWSubdomain()
+    public function testWithWWWSubdomain(): void
     {
         $routes = $this->getCollector();
 
@@ -1098,7 +1098,7 @@ public function testWithWWWSubdomain()
         $this->assertSame($expects, $routes->getRoutes());
     }
 
-    public function testWithDotCoSubdomain()
+    public function testWithDotCoSubdomain(): void
     {
         $routes = $this->getCollector();
 
@@ -1114,7 +1114,7 @@ public function testWithDotCoSubdomain()
         $this->assertSame($expects, $routes->getRoutes());
     }
 
-    public function testWithDifferentSubdomainMissing()
+    public function testWithDifferentSubdomainMissing(): void
     {
         $_SERVER['HTTP_HOST'] = 'adm.example.com';
 
@@ -1133,7 +1133,7 @@ public function testWithDifferentSubdomainMissing()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5959
      */
-    public function testWithNoSubdomainAndDot()
+    public function testWithNoSubdomainAndDot(): void
     {
         $_SERVER['HTTP_HOST'] = 'example.com';
 
@@ -1147,7 +1147,7 @@ public function testWithNoSubdomainAndDot()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1692
      */
-    public function testWithSubdomainOrdered()
+    public function testWithSubdomainOrdered(): void
     {
         $_SERVER['HTTP_HOST'] = 'adm.example.com';
 
@@ -1163,7 +1163,7 @@ public function testWithSubdomainOrdered()
         $this->assertSame($expects, $routes->getRoutes());
     }
 
-    public function testWillDiscoverLocal()
+    public function testWillDiscoverLocal(): void
     {
         $config = ['SampleSpace' => TESTPATH . '_support'];
 
@@ -1178,7 +1178,7 @@ public function testWillDiscoverLocal()
         $this->assertSame($match['testing'], '\TestController::index');
     }
 
-    public function testDiscoverLocalAllowsConfigToOverridePackages()
+    public function testDiscoverLocalAllowsConfigToOverridePackages(): void
     {
         $config = [
             'SampleSpace' => TESTPATH . '_support',
@@ -1197,7 +1197,7 @@ public function testDiscoverLocalAllowsConfigToOverridePackages()
         $this->assertSame($match['testing'], '\MainRoutes::index');
     }
 
-    public function testRoutesOptions()
+    public function testRoutesOptions(): void
     {
         $routes = $this->getCollector();
 
@@ -1208,7 +1208,7 @@ public function testRoutesOptions()
         ];
         $routes->add(
             'administrator',
-            static function () {},
+            static function (): void {},
             $options
         );
 
@@ -1220,20 +1220,20 @@ static function () {},
     /**
      * @dataProvider optionsProvider
      */
-    public function testRoutesOptionsWithSameFromTwoRoutes(array $options1, array $options2)
+    public function testRoutesOptionsWithSameFromTwoRoutes(array $options1, array $options2): void
     {
         $routes = $this->getCollector();
 
         // This is the first route for `administrator`.
         $routes->get(
             'administrator',
-            static function () {},
+            static function (): void {},
             $options1
         );
         // The second route for `administrator` should be ignored.
         $routes->get(
             'administrator',
-            static function () {},
+            static function (): void {},
             $options2
         );
 
@@ -1284,7 +1284,7 @@ public function optionsProvider(): iterable
         ];
     }
 
-    public function testRoutesOptionsForDifferentVerbs()
+    public function testRoutesOptionsForDifferentVerbs(): void
     {
         $routes = $this->getCollector();
 
@@ -1302,17 +1302,17 @@ public function testRoutesOptionsForDifferentVerbs()
         ];
         $routes->get(
             'administrator',
-            static function () {},
+            static function (): void {},
             $options1
         );
         $routes->post(
             'administrator',
-            static function () {},
+            static function (): void {},
             $options2
         );
         $routes->add(
             'administrator',
-            static function () {},
+            static function (): void {},
             $options3
         );
 
@@ -1329,7 +1329,7 @@ static function () {},
         $this->assertSame($options, ['as' => 'admin2', 'foo' => 'baz2', 'bar' => 'baz']);
     }
 
-    public function testRouteGroupWithFilterSimple()
+    public function testRouteGroupWithFilterSimple(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1337,7 +1337,7 @@ public function testRouteGroupWithFilterSimple()
         $routes->group(
             'admin',
             ['filter' => 'role'],
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->add('users', '\Users::list');
             }
         );
@@ -1348,7 +1348,7 @@ static function ($routes) {
         $this->assertSame([], $routes->getFiltersForRoute('admin/bosses'));
     }
 
-    public function testRouteGroupWithFilterWithParams()
+    public function testRouteGroupWithFilterWithParams(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1356,7 +1356,7 @@ public function testRouteGroupWithFilterWithParams()
         $routes->group(
             'admin',
             ['filter' => 'role:admin,manager'],
-            static function ($routes) {
+            static function ($routes): void {
                 $routes->add('users', '\Users::list');
             }
         );
@@ -1366,7 +1366,7 @@ static function ($routes) {
         $this->assertSame(['role:admin,manager'], $routes->getFiltersForRoute('admin/users'));
     }
 
-    public function test404OverrideNot()
+    public function test404OverrideNot(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1374,7 +1374,7 @@ public function test404OverrideNot()
         $this->assertNull($routes->get404Override());
     }
 
-    public function test404OverrideString()
+    public function test404OverrideString(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1383,18 +1383,18 @@ public function test404OverrideString()
         $this->assertSame('Explode', $routes->get404Override());
     }
 
-    public function test404OverrideCallable()
+    public function test404OverrideCallable(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
 
-        $routes->set404Override(static function () {
+        $routes->set404Override(static function (): void {
             echo 'Explode now';
         });
         $this->assertIsCallable($routes->get404Override());
     }
 
-    public function testOffsetParameters()
+    public function testOffsetParameters(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1409,7 +1409,7 @@ public function testOffsetParameters()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1697
      */
-    public function testRouteToWithSubdomainMatch()
+    public function testRouteToWithSubdomainMatch(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.example.com';
         Services::request()->setMethod('get');
@@ -1421,7 +1421,7 @@ public function testRouteToWithSubdomainMatch()
         $this->assertSame('/i/sth', $routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithSubdomainMismatch()
+    public function testRouteToWithSubdomainMismatch(): void
     {
         $_SERVER['HTTP_HOST'] = 'dev.example.com';
         Services::request()->setMethod('get');
@@ -1433,7 +1433,7 @@ public function testRouteToWithSubdomainMismatch()
         $this->assertFalse($routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithSubdomainNot()
+    public function testRouteToWithSubdomainNot(): void
     {
         $_SERVER['HTTP_HOST'] = 'example.com';
         Services::request()->setMethod('get');
@@ -1445,7 +1445,7 @@ public function testRouteToWithSubdomainNot()
         $this->assertFalse($routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithGenericSubdomainMatch()
+    public function testRouteToWithGenericSubdomainMatch(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.example.com';
         Services::request()->setMethod('get');
@@ -1457,7 +1457,7 @@ public function testRouteToWithGenericSubdomainMatch()
         $this->assertSame('/i/sth', $routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithGenericSubdomainMismatch()
+    public function testRouteToWithGenericSubdomainMismatch(): void
     {
         $_SERVER['HTTP_HOST'] = 'dev.example.com';
         Services::request()->setMethod('get');
@@ -1469,7 +1469,7 @@ public function testRouteToWithGenericSubdomainMismatch()
         $this->assertSame('/i/sth', $routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithGenericSubdomainNot()
+    public function testRouteToWithGenericSubdomainNot(): void
     {
         $_SERVER['HTTP_HOST'] = 'example.com';
         Services::request()->setMethod('get');
@@ -1481,7 +1481,7 @@ public function testRouteToWithGenericSubdomainNot()
         $this->assertFalse($routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithoutSubdomainMatch()
+    public function testRouteToWithoutSubdomainMatch(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.example.com';
         Services::request()->setMethod('get');
@@ -1493,7 +1493,7 @@ public function testRouteToWithoutSubdomainMatch()
         $this->assertFalse($routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithoutSubdomainMismatch()
+    public function testRouteToWithoutSubdomainMismatch(): void
     {
         $_SERVER['HTTP_HOST'] = 'dev.example.com';
         Services::request()->setMethod('get');
@@ -1505,7 +1505,7 @@ public function testRouteToWithoutSubdomainMismatch()
         $this->assertFalse($routes->reverseRoute('doc_item', 'sth'));
     }
 
-    public function testRouteToWithoutSubdomainNot()
+    public function testRouteToWithoutSubdomainNot(): void
     {
         $_SERVER['HTTP_HOST'] = 'example.com';
         Services::request()->setMethod('get');
@@ -1522,7 +1522,7 @@ public function testRouteToWithoutSubdomainNot()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1692
      */
-    public function testRouteOverwritingDifferentSubdomains()
+    public function testRouteOverwritingDifferentSubdomains(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.domain.com';
         Services::request()->setMethod('get');
@@ -1543,7 +1543,7 @@ public function testRouteOverwritingDifferentSubdomains()
         $this->assertSame($expects, $router->handle('/'));
     }
 
-    public function testRouteOverwritingTwoRules()
+    public function testRouteOverwritingTwoRules(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.domain.com';
         Services::request()->setMethod('get');
@@ -1564,7 +1564,7 @@ public function testRouteOverwritingTwoRules()
         $this->assertSame($expects, $router->handle('/'));
     }
 
-    public function testRouteOverwritingTwoRulesLastApplies()
+    public function testRouteOverwritingTwoRulesLastApplies(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.domain.com';
         Services::request()->setMethod('get');
@@ -1584,7 +1584,7 @@ public function testRouteOverwritingTwoRulesLastApplies()
         $this->assertSame($expects, $router->handle('/'));
     }
 
-    public function testRouteOverwritingMatchingSubdomain()
+    public function testRouteOverwritingMatchingSubdomain(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.domain.com';
         Services::request()->setMethod('get');
@@ -1604,7 +1604,7 @@ public function testRouteOverwritingMatchingSubdomain()
         $this->assertSame($expects, $router->handle('/'));
     }
 
-    public function testRouteOverwritingMatchingHost()
+    public function testRouteOverwritingMatchingHost(): void
     {
         $_SERVER['HTTP_HOST'] = 'doc.domain.com';
         Services::request()->setMethod('get');
@@ -1629,7 +1629,7 @@ public function testRouteOverwritingMatchingHost()
      *
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2423
      */
-    public function testRouteDefaultNameSpace()
+    public function testRouteDefaultNameSpace(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1643,7 +1643,7 @@ public function testRouteDefaultNameSpace()
         $this->assertSame($expects, $router->handle('/'));
     }
 
-    public function testZeroAsURIPath()
+    public function testZeroAsURIPath(): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1670,7 +1670,7 @@ public function provideRouteDefaultNamespace(): iterable
      *
      * @param mixed $namespace
      */
-    public function testAutoRoutesControllerNameReturnsFQCN($namespace)
+    public function testAutoRoutesControllerNameReturnsFQCN($namespace): void
     {
         $routes = $this->getCollector();
         $routes->setAutoRoute(true);
@@ -1687,7 +1687,7 @@ public function testAutoRoutesControllerNameReturnsFQCN($namespace)
      *
      * @param mixed $namespace
      */
-    public function testRoutesControllerNameReturnsFQCN($namespace)
+    public function testRoutesControllerNameReturnsFQCN($namespace): void
     {
         Services::request()->setMethod('get');
         $routes = $this->getCollector();
@@ -1701,7 +1701,7 @@ public function testRoutesControllerNameReturnsFQCN($namespace)
         $this->assertSame('\App\\Controllers\\Product', $router->controllerName());
     }
 
-    public function testRoutePriorityDetected()
+    public function testRoutePriorityDetected(): void
     {
         $collection = $this->getCollector();
 
@@ -1716,7 +1716,7 @@ public function testRoutePriorityDetected()
         $this->assertTrue($this->getPrivateProperty($collection, 'prioritizeDetected'));
     }
 
-    public function testRoutePriorityValue()
+    public function testRoutePriorityValue(): void
     {
         $collection = $this->getCollector();
 
@@ -1730,7 +1730,7 @@ public function testRoutePriorityValue()
         $this->assertSame(1, $collection->getRoutesOptions('string-negative-integer')['priority']);
     }
 
-    public function testGetRegisteredControllersReturnsControllerForHTTPverb()
+    public function testGetRegisteredControllersReturnsControllerForHTTPverb(): void
     {
         $collection = $this->getCollector();
         $collection->get('test', '\App\Controllers\Hello::get');
@@ -1751,7 +1751,7 @@ public function testGetRegisteredControllersReturnsControllerForHTTPverb()
         $this->assertSame($expects, $routes);
     }
 
-    public function testGetRegisteredControllersReturnsTwoControllers()
+    public function testGetRegisteredControllersReturnsTwoControllers(): void
     {
         $collection = $this->getCollector();
         $collection->post('test', '\App\Controllers\Test::post');
@@ -1766,7 +1766,7 @@ public function testGetRegisteredControllersReturnsTwoControllers()
         $this->assertSame($expects, $routes);
     }
 
-    public function testGetRegisteredControllersReturnsOneControllerWhenTwoRoutsWithDiffernetMethods()
+    public function testGetRegisteredControllersReturnsOneControllerWhenTwoRoutsWithDiffernetMethods(): void
     {
         $collection = $this->getCollector();
         $collection->post('test', '\App\Controllers\Test::test');
@@ -1780,7 +1780,7 @@ public function testGetRegisteredControllersReturnsOneControllerWhenTwoRoutsWith
         $this->assertSame($expects, $routes);
     }
 
-    public function testGetRegisteredControllersReturnsAllControllers()
+    public function testGetRegisteredControllersReturnsAllControllers(): void
     {
         $collection = $this->getCollector();
         $collection->get('test', '\App\Controllers\HelloGet::get');
@@ -1797,7 +1797,7 @@ public function testGetRegisteredControllersReturnsAllControllers()
         $this->assertSame($expects, $routes);
     }
 
-    public function testGetRegisteredControllersReturnsControllerByAddMethod()
+    public function testGetRegisteredControllersReturnsControllerByAddMethod(): void
     {
         $collection = $this->getCollector();
         $collection->get('test', '\App\Controllers\Hello::get');
@@ -1812,10 +1812,10 @@ public function testGetRegisteredControllersReturnsControllerByAddMethod()
         $this->assertSame($expects, $routes);
     }
 
-    public function testGetRegisteredControllersDoesNotReturnClosures()
+    public function testGetRegisteredControllersDoesNotReturnClosures(): void
     {
         $collection = $this->getCollector();
-        $collection->get('feed', static function () {
+        $collection->get('feed', static function (): void {
         });
 
         $routes = $collection->getRegisteredControllers('*');
@@ -1824,7 +1824,7 @@ public function testGetRegisteredControllersDoesNotReturnClosures()
         $this->assertSame($expects, $routes);
     }
 
-    public function testUseSupportedLocalesOnly()
+    public function testUseSupportedLocalesOnly(): void
     {
         config('App')->supportedLocales = ['en'];
 
diff --git a/tests/system/Router/RouterTest.php b/tests/system/Router/RouterTest.php
index 1ba0ee9ed798..c068569c4576 100644
--- a/tests/system/Router/RouterTest.php
+++ b/tests/system/Router/RouterTest.php
@@ -63,7 +63,7 @@ protected function setUp(): void
         $this->request->setMethod('get');
     }
 
-    public function testEmptyURIMatchesRoot()
+    public function testEmptyURIMatchesRoot(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -73,7 +73,7 @@ public function testEmptyURIMatchesRoot()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testZeroAsURIPath()
+    public function testZeroAsURIPath(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -82,7 +82,7 @@ public function testZeroAsURIPath()
         $router->handle('0');
     }
 
-    public function testURIMapsToController()
+    public function testURIMapsToController(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -92,7 +92,7 @@ public function testURIMapsToController()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testURIWithTrailingSlashMapsToController()
+    public function testURIWithTrailingSlashMapsToController(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -102,7 +102,7 @@ public function testURIWithTrailingSlashMapsToController()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testURIMapsToControllerAltMethod()
+    public function testURIMapsToControllerAltMethod(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -112,7 +112,7 @@ public function testURIMapsToControllerAltMethod()
         $this->assertSame('posts', $router->methodName());
     }
 
-    public function testURIMapsToNamespacedController()
+    public function testURIMapsToNamespacedController(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -122,7 +122,7 @@ public function testURIMapsToNamespacedController()
         $this->assertSame('list_all', $router->methodName());
     }
 
-    public function testURIMapsParamsToBackReferences()
+    public function testURIMapsParamsToBackReferences(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -132,7 +132,7 @@ public function testURIMapsParamsToBackReferences()
         $this->assertSame(['123'], $router->params());
     }
 
-    public function testURIMapsParamsToRearrangedBackReferences()
+    public function testURIMapsParamsToRearrangedBackReferences(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -142,7 +142,7 @@ public function testURIMapsParamsToRearrangedBackReferences()
         $this->assertSame(['123'], $router->params());
     }
 
-    public function testURIMapsParamsToBackReferencesWithUnused()
+    public function testURIMapsParamsToBackReferencesWithUnused(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -155,7 +155,7 @@ public function testURIMapsParamsToBackReferencesWithUnused()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/672
      */
-    public function testURIMapsParamsWithMany()
+    public function testURIMapsParamsWithMany(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -165,7 +165,7 @@ public function testURIMapsParamsWithMany()
         $this->assertSame(['123', 'abc', 'FOO'], $router->params());
     }
 
-    public function testURIWithTrailingSlashMapsParamsWithMany()
+    public function testURIWithTrailingSlashMapsParamsWithMany(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -175,7 +175,7 @@ public function testURIWithTrailingSlashMapsParamsWithMany()
         $this->assertSame(['123', 'abc', 'FOO'], $router->params());
     }
 
-    public function testClosures()
+    public function testClosures(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -189,7 +189,7 @@ public function testClosures()
         $this->assertSame($expects, '123-alpha');
     }
 
-    public function testAutoRouteFindsDefaultControllerAndMethod()
+    public function testAutoRouteFindsDefaultControllerAndMethod(): void
     {
         $this->collection->setAutoRoute(true);
         $this->collection->setDefaultController('Test');
@@ -202,7 +202,7 @@ public function testAutoRouteFindsDefaultControllerAndMethod()
         $this->assertSame('test', $router->methodName());
     }
 
-    public function testAutoRouteFindsControllerWithFileAndMethod()
+    public function testAutoRouteFindsControllerWithFileAndMethod(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -213,7 +213,7 @@ public function testAutoRouteFindsControllerWithFileAndMethod()
         $this->assertSame('someMethod', $router->methodName());
     }
 
-    public function testAutoRouteFindsControllerWithFile()
+    public function testAutoRouteFindsControllerWithFile(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -224,7 +224,7 @@ public function testAutoRouteFindsControllerWithFile()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testAutoRouteFindsControllerWithSubfolder()
+    public function testAutoRouteFindsControllerWithSubfolder(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -239,7 +239,7 @@ public function testAutoRouteFindsControllerWithSubfolder()
         $this->assertSame('someMethod', $router->methodName());
     }
 
-    public function testAutoRouteFindsDashedSubfolder()
+    public function testAutoRouteFindsDashedSubfolder(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -256,7 +256,7 @@ public function testAutoRouteFindsDashedSubfolder()
         $this->assertSame('somemethod', $router->methodName());
     }
 
-    public function testAutoRouteFindsDashedController()
+    public function testAutoRouteFindsDashedController(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -275,7 +275,7 @@ public function testAutoRouteFindsDashedController()
         $this->assertSame('somemethod', $router->methodName());
     }
 
-    public function testAutoRouteFindsDashedMethod()
+    public function testAutoRouteFindsDashedMethod(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -294,7 +294,7 @@ public function testAutoRouteFindsDashedMethod()
         $this->assertSame('dash_method', $router->methodName());
     }
 
-    public function testAutoRouteFindsDefaultDashFolder()
+    public function testAutoRouteFindsDefaultDashFolder(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -311,7 +311,7 @@ public function testAutoRouteFindsDefaultDashFolder()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testAutoRouteFindsMByteDir()
+    public function testAutoRouteFindsMByteDir(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -328,7 +328,7 @@ public function testAutoRouteFindsMByteDir()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testAutoRouteFindsMByteController()
+    public function testAutoRouteFindsMByteController(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -344,7 +344,7 @@ public function testAutoRouteFindsMByteController()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testAutoRouteRejectsSingleDot()
+    public function testAutoRouteRejectsSingleDot(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -355,7 +355,7 @@ public function testAutoRouteRejectsSingleDot()
         $router->autoRoute('.');
     }
 
-    public function testAutoRouteRejectsDoubleDot()
+    public function testAutoRouteRejectsDoubleDot(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -366,7 +366,7 @@ public function testAutoRouteRejectsDoubleDot()
         $router->autoRoute('..');
     }
 
-    public function testAutoRouteRejectsMidDot()
+    public function testAutoRouteRejectsMidDot(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -377,7 +377,7 @@ public function testAutoRouteRejectsMidDot()
         $router->autoRoute('Foo.bar');
     }
 
-    public function testAutoRouteRejectsInitController()
+    public function testAutoRouteRejectsInitController(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -388,7 +388,7 @@ public function testAutoRouteRejectsInitController()
         $router->autoRoute('home/initController');
     }
 
-    public function testExceptionMessageWhenRouteNotFound()
+    public function testExceptionMessageWhenRouteNotFound(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -398,7 +398,7 @@ public function testExceptionMessageWhenRouteNotFound()
         $router->handle('url/not-exists');
     }
 
-    public function testDetectsLocales()
+    public function testDetectsLocales(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -413,7 +413,7 @@ public function testDetectsLocales()
         $this->assertSame('bg', $router->getLocale());
     }
 
-    public function testRouteResource()
+    public function testRouteResource(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -423,7 +423,7 @@ public function testRouteResource()
         $this->assertSame('list_all', $router->methodName());
     }
 
-    public function testRouteWithSlashInControllerName()
+    public function testRouteWithSlashInControllerName(): void
     {
         $this->expectExceptionMessage(
             'The namespace delimiter is a backslash (\), not a slash (/). Route handler: "\App/Admin/Admins::edit_show/$1"'
@@ -434,7 +434,7 @@ public function testRouteWithSlashInControllerName()
         $router->handle('admin/admins/edit/1');
     }
 
-    public function testRouteWithLeadingSlash()
+    public function testRouteWithLeadingSlash(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -444,7 +444,7 @@ public function testRouteWithLeadingSlash()
         $this->assertSame('index', $router->methodName());
     }
 
-    public function testRouteWithDynamicController()
+    public function testRouteWithDynamicController(): void
     {
         $this->expectException(RouterException::class);
         $this->expectExceptionMessage('A dynamic controller is not allowed for security reasons. Route handler: "\$2::$3/$1"');
@@ -455,19 +455,19 @@ public function testRouteWithDynamicController()
     }
 
     // options need to be declared separately, to not confuse PHPCBF
-    public function testMatchedRouteOptions()
+    public function testMatchedRouteOptions(): void
     {
         $optionsFoo = [
             'as'  => 'login',
             'foo' => 'baz',
         ];
-        $this->collection->add('foo', static function () {
+        $this->collection->add('foo', static function (): void {
         }, $optionsFoo);
         $optionsBaz = [
             'as'  => 'admin',
             'foo' => 'bar',
         ];
-        $this->collection->add('baz', static function () {
+        $this->collection->add('baz', static function (): void {
         }, $optionsBaz);
 
         $router = new Router($this->collection, $this->request);
@@ -477,11 +477,11 @@ public function testMatchedRouteOptions()
         $this->assertSame($router->getMatchedRouteOptions(), ['as' => 'login', 'foo' => 'baz']);
     }
 
-    public function testRouteWorksWithFilters()
+    public function testRouteWorksWithFilters(): void
     {
         $collection = $this->collection;
 
-        $collection->group('foo', ['filter' => 'test'], static function ($routes) {
+        $collection->group('foo', ['filter' => 'test'], static function ($routes): void {
             $routes->add('bar', 'TestController::foobar');
         });
 
@@ -497,7 +497,7 @@ public function testRouteWorksWithFilters()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1247
      */
-    public function testGroupedResourceRoutesWithFilters()
+    public function testGroupedResourceRoutesWithFilters(): void
     {
         $group = [
             'api',
@@ -505,7 +505,7 @@ public function testGroupedResourceRoutesWithFilters()
                 'namespace' => 'App\Controllers\Api',
                 'filter'    => 'api-auth',
             ],
-            static function (RouteCollection $routes) {
+            static function (RouteCollection $routes): void {
                 $routes->resource('posts', [
                     'controller' => 'PostController',
                 ]);
@@ -590,7 +590,7 @@ static function (RouteCollection $routes) {
         $this->assertSame('api-auth', $router->getFilter());
     }
 
-    public function testRouteWorksWithClassnameFilter()
+    public function testRouteWorksWithClassnameFilter(): void
     {
         $collection = $this->collection;
 
@@ -606,7 +606,7 @@ public function testRouteWorksWithClassnameFilter()
         $this->resetServices();
     }
 
-    public function testRouteWorksWithMultipleFilters()
+    public function testRouteWorksWithMultipleFilters(): void
     {
         $feature                  = config('Feature');
         $feature->multipleFilters = true;
@@ -628,7 +628,7 @@ public function testRouteWorksWithMultipleFilters()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1240
      */
-    public function testMatchesCorrectlyWithMixedVerbs()
+    public function testMatchesCorrectlyWithMixedVerbs(): void
     {
         $this->collection->setHTTPVerb('get');
 
@@ -659,7 +659,7 @@ public function testMatchesCorrectlyWithMixedVerbs()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1354
      */
-    public function testRouteOrder()
+    public function testRouteOrder(): void
     {
         $this->collection->post('auth', 'Main::auth_post');
         $this->collection->add('auth', 'Main::index');
@@ -672,7 +672,7 @@ public function testRouteOrder()
         $this->assertSame('auth_post', $router->methodName());
     }
 
-    public function testRoutePriorityOrder()
+    public function testRoutePriorityOrder(): void
     {
         $this->collection->add('main', 'Main::index');
         $this->collection->add('(.*)', 'Main::wildcard', ['priority' => 1]);
@@ -696,7 +696,7 @@ public function testRoutePriorityOrder()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1564
      */
-    public function testTranslateURIDashes()
+    public function testTranslateURIDashes(): void
     {
         $router = new Router($this->collection, $this->request);
 
@@ -711,7 +711,7 @@ public function testTranslateURIDashes()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1564
      */
-    public function testTranslateURIDashesForParams()
+    public function testTranslateURIDashesForParams(): void
     {
         $router = new Router($this->collection, $this->request);
         $router->setTranslateURIDashes(true);
@@ -726,7 +726,7 @@ public function testTranslateURIDashesForParams()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1564
      */
-    public function testTranslateURIDashesForAutoRoute()
+    public function testTranslateURIDashesForAutoRoute(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -741,7 +741,7 @@ public function testTranslateURIDashesForAutoRoute()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2032
      */
-    public function testAutoRouteMatchesZeroParams()
+    public function testAutoRouteMatchesZeroParams(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -761,7 +761,7 @@ public function testAutoRouteMatchesZeroParams()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2965
      */
-    public function testAutoRouteMethodEmpty()
+    public function testAutoRouteMethodEmpty(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -776,7 +776,7 @@ public function testAutoRouteMethodEmpty()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3169
      */
-    public function testRegularExpressionWithUnicode()
+    public function testRegularExpressionWithUnicode(): void
     {
         $this->collection->get('news/([a-z0-9\x{0980}-\x{09ff}-]+)', 'News::view/$1');
 
@@ -795,7 +795,7 @@ public function testRegularExpressionWithUnicode()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3169
      */
-    public function testRegularExpressionPlaceholderWithUnicode()
+    public function testRegularExpressionPlaceholderWithUnicode(): void
     {
         $this->collection->addPlaceholder('custom', '[a-z0-9\x{0980}-\x{09ff}-]+');
         $this->collection->get('news/(:custom)', 'News::view/$1');
@@ -812,7 +812,7 @@ public function testRegularExpressionPlaceholderWithUnicode()
         $this->assertSame($expected, $router->params());
     }
 
-    public function testRouterPriorDirectory()
+    public function testRouterPriorDirectory(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -825,7 +825,7 @@ public function testRouterPriorDirectory()
         $this->assertSame('some_method', $router->methodName());
     }
 
-    public function testSetDirectoryValid()
+    public function testSetDirectoryValid(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -834,7 +834,7 @@ public function testSetDirectoryValid()
         $this->assertSame('foo/bar/baz/', $router->directory());
     }
 
-    public function testSetDirectoryInvalid()
+    public function testSetDirectoryInvalid(): void
     {
         $this->collection->setAutoRoute(true);
         $router = new Router($this->collection, $this->request);
@@ -856,7 +856,7 @@ public function testRedirectRoute(
         string $url,
         string $expectedPath,
         string $alias
-    ) {
+    ): void {
         $collection = clone $this->collection;
         $collection->resetRoutes();
 
diff --git a/tests/system/Security/SecurityCSRFCookieRandomizeTokenTest.php b/tests/system/Security/SecurityCSRFCookieRandomizeTokenTest.php
index 93f749ffc604..bf49eb1ab1fe 100644
--- a/tests/system/Security/SecurityCSRFCookieRandomizeTokenTest.php
+++ b/tests/system/Security/SecurityCSRFCookieRandomizeTokenTest.php
@@ -56,7 +56,7 @@ protected function setUp(): void
         $this->resetServices();
     }
 
-    public function testTokenIsReadFromCookie()
+    public function testTokenIsReadFromCookie(): void
     {
         $security = new MockSecurity(new MockAppConfig());
 
@@ -66,7 +66,7 @@ public function testTokenIsReadFromCookie()
         );
     }
 
-    public function testCSRFVerifySetNewCookie()
+    public function testCSRFVerifySetNewCookie(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['foo']              = 'bar';
diff --git a/tests/system/Security/SecurityCSRFSessionRandomizeTokenTest.php b/tests/system/Security/SecurityCSRFSessionRandomizeTokenTest.php
index 6086472d3f4c..8e593903595c 100644
--- a/tests/system/Security/SecurityCSRFSessionRandomizeTokenTest.php
+++ b/tests/system/Security/SecurityCSRFSessionRandomizeTokenTest.php
@@ -102,7 +102,7 @@ private function injectSession(string $hash): void
         Services::injectMock('session', $session);
     }
 
-    public function testHashIsReadFromSession()
+    public function testHashIsReadFromSession(): void
     {
         $security = new MockSecurity(new MockAppConfig());
 
@@ -112,7 +112,7 @@ public function testHashIsReadFromSession()
         );
     }
 
-    public function testCSRFVerifyPostNoToken()
+    public function testCSRFVerifyPostNoToken(): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('The action you requested is not allowed.');
@@ -127,7 +127,7 @@ public function testCSRFVerifyPostNoToken()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPostThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPostThrowsExceptionOnNoMatch(): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('The action you requested is not allowed.');
@@ -142,7 +142,7 @@ public function testCSRFVerifyPostThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPostInvalidToken()
+    public function testCSRFVerifyPostInvalidToken(): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('The action you requested is not allowed.');
@@ -157,7 +157,7 @@ public function testCSRFVerifyPostInvalidToken()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPostReturnsSelfOnMatch()
+    public function testCSRFVerifyPostReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['foo']              = 'bar';
@@ -172,7 +172,7 @@ public function testCSRFVerifyPostReturnsSelfOnMatch()
         $this->assertCount(1, $_POST);
     }
 
-    public function testCSRFVerifyPOSTHeaderThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPOSTHeaderThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
 
@@ -187,7 +187,7 @@ public function testCSRFVerifyPOSTHeaderThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPOSTHeaderReturnsSelfOnMatch()
+    public function testCSRFVerifyPOSTHeaderReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['foo']              = 'bar';
@@ -202,7 +202,7 @@ public function testCSRFVerifyPOSTHeaderReturnsSelfOnMatch()
         $this->assertCount(1, $_POST);
     }
 
-    public function testCSRFVerifyPUTHeaderThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPUTHeaderThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'PUT';
 
@@ -217,7 +217,7 @@ public function testCSRFVerifyPUTHeaderThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPUTHeaderReturnsSelfOnMatch()
+    public function testCSRFVerifyPUTHeaderReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'PUT';
 
@@ -230,7 +230,7 @@ public function testCSRFVerifyPUTHeaderReturnsSelfOnMatch()
         $this->assertLogged('info', 'CSRF token verified.');
     }
 
-    public function testCSRFVerifyJsonThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyJsonThrowsExceptionOnNoMatch(): void
     {
         $this->expectException(SecurityException::class);
         $this->expectExceptionMessage('The action you requested is not allowed.');
@@ -245,7 +245,7 @@ public function testCSRFVerifyJsonThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyJsonReturnsSelfOnMatch()
+    public function testCSRFVerifyJsonReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
 
@@ -259,7 +259,7 @@ public function testCSRFVerifyJsonReturnsSelfOnMatch()
         $this->assertSame('{"foo":"bar"}', $request->getBody());
     }
 
-    public function testRegenerateWithFalseSecurityRegenerateProperty()
+    public function testRegenerateWithFalseSecurityRegenerateProperty(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['csrf_test_name']   = $this->randomizedToken;
@@ -280,7 +280,7 @@ public function testRegenerateWithFalseSecurityRegenerateProperty()
         $this->assertSame($oldHash, $newHash);
     }
 
-    public function testRegenerateWithTrueSecurityRegenerateProperty()
+    public function testRegenerateWithTrueSecurityRegenerateProperty(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['csrf_test_name']   = $this->randomizedToken;
diff --git a/tests/system/Security/SecurityCSRFSessionTest.php b/tests/system/Security/SecurityCSRFSessionTest.php
index 7fbd7096853f..12bee2761732 100644
--- a/tests/system/Security/SecurityCSRFSessionTest.php
+++ b/tests/system/Security/SecurityCSRFSessionTest.php
@@ -95,14 +95,14 @@ private function injectSession(string $hash): void
         Services::injectMock('session', $session);
     }
 
-    public function testHashIsReadFromSession()
+    public function testHashIsReadFromSession(): void
     {
         $security = new Security(new MockAppConfig());
 
         $this->assertSame($this->hash, $security->getHash());
     }
 
-    public function testCSRFVerifyPostThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPostThrowsExceptionOnNoMatch(): void
     {
         $this->expectException(SecurityException::class);
 
@@ -116,7 +116,7 @@ public function testCSRFVerifyPostThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPostReturnsSelfOnMatch()
+    public function testCSRFVerifyPostReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['foo']              = 'bar';
@@ -131,7 +131,7 @@ public function testCSRFVerifyPostReturnsSelfOnMatch()
         $this->assertCount(1, $_POST);
     }
 
-    public function testCSRFVerifyPOSTHeaderThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPOSTHeaderThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
 
@@ -144,7 +144,7 @@ public function testCSRFVerifyPOSTHeaderThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPOSTHeaderReturnsSelfOnMatch()
+    public function testCSRFVerifyPOSTHeaderReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['foo']              = 'bar';
@@ -159,7 +159,7 @@ public function testCSRFVerifyPOSTHeaderReturnsSelfOnMatch()
         $this->assertCount(1, $_POST);
     }
 
-    public function testCSRFVerifyPUTHeaderThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPUTHeaderThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'PUT';
 
@@ -172,7 +172,7 @@ public function testCSRFVerifyPUTHeaderThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPUTHeaderReturnsSelfOnMatch()
+    public function testCSRFVerifyPUTHeaderReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'PUT';
 
@@ -185,7 +185,7 @@ public function testCSRFVerifyPUTHeaderReturnsSelfOnMatch()
         $this->assertLogged('info', 'CSRF token verified.');
     }
 
-    public function testCSRFVerifyJsonThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyJsonThrowsExceptionOnNoMatch(): void
     {
         $this->expectException(SecurityException::class);
 
@@ -199,7 +199,7 @@ public function testCSRFVerifyJsonThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyJsonReturnsSelfOnMatch()
+    public function testCSRFVerifyJsonReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
 
@@ -213,7 +213,7 @@ public function testCSRFVerifyJsonReturnsSelfOnMatch()
         $this->assertSame('{"foo":"bar"}', $request->getBody());
     }
 
-    public function testRegenerateWithFalseSecurityRegenerateProperty()
+    public function testRegenerateWithFalseSecurityRegenerateProperty(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['csrf_test_name']   = '8b9218a55906f9dcc1dc263dce7f005a';
@@ -233,7 +233,7 @@ public function testRegenerateWithFalseSecurityRegenerateProperty()
         $this->assertSame($oldHash, $newHash);
     }
 
-    public function testRegenerateWithTrueSecurityRegenerateProperty()
+    public function testRegenerateWithTrueSecurityRegenerateProperty(): void
     {
         $_SERVER['REQUEST_METHOD'] = 'POST';
         $_POST['csrf_test_name']   = '8b9218a55906f9dcc1dc263dce7f005a';
diff --git a/tests/system/Security/SecurityTest.php b/tests/system/Security/SecurityTest.php
index f610add149f0..9dd2aa26e77b 100644
--- a/tests/system/Security/SecurityTest.php
+++ b/tests/system/Security/SecurityTest.php
@@ -41,7 +41,7 @@ protected function setUp(): void
         $this->resetServices();
     }
 
-    public function testBasicConfigIsSaved()
+    public function testBasicConfigIsSaved(): void
     {
         $security = new MockSecurity(new MockAppConfig());
 
@@ -51,7 +51,7 @@ public function testBasicConfigIsSaved()
         $this->assertSame('csrf_test_name', $security->getTokenName());
     }
 
-    public function testHashIsReadFromCookie()
+    public function testHashIsReadFromCookie(): void
     {
         $_COOKIE['csrf_cookie_name'] = '8b9218a55906f9dcc1dc263dce7f005a';
 
@@ -63,7 +63,7 @@ public function testHashIsReadFromCookie()
         );
     }
 
-    public function testGetHashSetsCookieWhenGETWithoutCSRFCookie()
+    public function testGetHashSetsCookieWhenGETWithoutCSRFCookie(): void
     {
         $security = new MockSecurity(new MockAppConfig());
 
@@ -75,7 +75,7 @@ public function testGetHashSetsCookieWhenGETWithoutCSRFCookie()
         $this->assertSame($security->getHash(), $cookie->getValue());
     }
 
-    public function testGetHashReturnsCSRFCookieWhenGETWithCSRFCookie()
+    public function testGetHashReturnsCSRFCookieWhenGETWithCSRFCookie(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'GET';
         $_COOKIE['csrf_cookie_name'] = '8b9218a55906f9dcc1dc263dce7f005a';
@@ -87,7 +87,7 @@ public function testGetHashReturnsCSRFCookieWhenGETWithCSRFCookie()
         $this->assertSame($_COOKIE['csrf_cookie_name'], $security->getHash());
     }
 
-    public function testCSRFVerifyPostThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyPostThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_POST['csrf_test_name']     = '8b9218a55906f9dcc1dc263dce7f005a';
@@ -105,7 +105,7 @@ public function testCSRFVerifyPostThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyPostReturnsSelfOnMatch()
+    public function testCSRFVerifyPostReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_POST['foo']                = 'bar';
@@ -126,7 +126,7 @@ public function testCSRFVerifyPostReturnsSelfOnMatch()
         $this->assertCount(1, $_POST);
     }
 
-    public function testCSRFVerifyHeaderThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyHeaderThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_COOKIE['csrf_cookie_name'] = '8b9218a55906f9dcc1dc263dce7f005b';
@@ -145,7 +145,7 @@ public function testCSRFVerifyHeaderThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyHeaderReturnsSelfOnMatch()
+    public function testCSRFVerifyHeaderReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_POST['foo']                = 'bar';
@@ -167,7 +167,7 @@ public function testCSRFVerifyHeaderReturnsSelfOnMatch()
         $this->assertCount(1, $_POST);
     }
 
-    public function testCSRFVerifyJsonThrowsExceptionOnNoMatch()
+    public function testCSRFVerifyJsonThrowsExceptionOnNoMatch(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_COOKIE['csrf_cookie_name'] = '8b9218a55906f9dcc1dc263dce7f005b';
@@ -188,7 +188,7 @@ public function testCSRFVerifyJsonThrowsExceptionOnNoMatch()
         $security->verify($request);
     }
 
-    public function testCSRFVerifyJsonReturnsSelfOnMatch()
+    public function testCSRFVerifyJsonReturnsSelfOnMatch(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_COOKIE['csrf_cookie_name'] = '8b9218a55906f9dcc1dc263dce7f005a';
@@ -211,7 +211,7 @@ public function testCSRFVerifyJsonReturnsSelfOnMatch()
         $this->assertSame('{"foo":"bar"}', $request->getBody());
     }
 
-    public function testSanitizeFilename()
+    public function testSanitizeFilename(): void
     {
         $security = new MockSecurity(new MockAppConfig());
 
@@ -220,7 +220,7 @@ public function testSanitizeFilename()
         $this->assertSame('foo', $security->sanitizeFilename($filename));
     }
 
-    public function testRegenerateWithFalseSecurityRegenerateProperty()
+    public function testRegenerateWithFalseSecurityRegenerateProperty(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_POST['csrf_test_name']     = '8b9218a55906f9dcc1dc263dce7f005a';
@@ -245,7 +245,7 @@ public function testRegenerateWithFalseSecurityRegenerateProperty()
         $this->assertSame($oldHash, $newHash);
     }
 
-    public function testRegenerateWithFalseSecurityRegeneratePropertyManually()
+    public function testRegenerateWithFalseSecurityRegeneratePropertyManually(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_POST['csrf_test_name']     = '8b9218a55906f9dcc1dc263dce7f005a';
@@ -271,7 +271,7 @@ public function testRegenerateWithFalseSecurityRegeneratePropertyManually()
         $this->assertNotSame($oldHash, $newHash);
     }
 
-    public function testRegenerateWithTrueSecurityRegenerateProperty()
+    public function testRegenerateWithTrueSecurityRegenerateProperty(): void
     {
         $_SERVER['REQUEST_METHOD']   = 'POST';
         $_POST['csrf_test_name']     = '8b9218a55906f9dcc1dc263dce7f005a';
diff --git a/tests/system/Session/Handlers/Database/AbstractHandlerTestCase.php b/tests/system/Session/Handlers/Database/AbstractHandlerTestCase.php
index 145f1e942365..31a684ae3fb3 100644
--- a/tests/system/Session/Handlers/Database/AbstractHandlerTestCase.php
+++ b/tests/system/Session/Handlers/Database/AbstractHandlerTestCase.php
@@ -44,13 +44,13 @@ protected function setUp(): void
 
     abstract protected function getInstance($options = []);
 
-    public function testOpen()
+    public function testOpen(): void
     {
         $handler = $this->getInstance();
         $this->assertTrue($handler->open('ci_sessions', 'ci_session'));
     }
 
-    public function testReadSuccess()
+    public function testReadSuccess(): void
     {
         $handler  = $this->getInstance();
         $expected = '__ci_last_regenerate|i:1624650854;_ci_previous_url|s:40:\"http://localhost/index.php/home/index\";';
@@ -60,7 +60,7 @@ public function testReadSuccess()
         $this->assertSame('1483201a66afd2bd671e4a67dc6ecf24', $this->getPrivateProperty($handler, 'fingerprint'));
     }
 
-    public function testReadFailure()
+    public function testReadFailure(): void
     {
         $handler = $this->getInstance();
         $this->assertSame('', $handler->read('123456b43phsnnf8if6bo33b635e4321'));
@@ -69,7 +69,7 @@ public function testReadFailure()
         $this->assertSame('d41d8cd98f00b204e9800998ecf8427e', $this->getPrivateProperty($handler, 'fingerprint'));
     }
 
-    public function testWriteInsert()
+    public function testWriteInsert(): void
     {
         $handler = $this->getInstance();
 
@@ -88,7 +88,7 @@ public function testWriteInsert()
         $this->assertSame('1483201a66afd2bd671e4a67dc6ecf24', $this->getPrivateProperty($handler, 'fingerprint'));
     }
 
-    public function testWriteUpdate()
+    public function testWriteUpdate(): void
     {
         $handler = $this->getInstance();
 
@@ -112,7 +112,7 @@ public function testWriteUpdate()
         $this->assertSame('1483201a66afd2bd671e4a67dc6ecf24', $this->getPrivateProperty($handler, 'fingerprint'));
     }
 
-    public function testGC()
+    public function testGC(): void
     {
         $handler = $this->getInstance();
         $this->assertSame(1, $handler->gc(3600));
diff --git a/tests/system/Session/Handlers/Database/RedisHandlerTest.php b/tests/system/Session/Handlers/Database/RedisHandlerTest.php
index 08505afbdf13..032b4e6c77cd 100644
--- a/tests/system/Session/Handlers/Database/RedisHandlerTest.php
+++ b/tests/system/Session/Handlers/Database/RedisHandlerTest.php
@@ -53,7 +53,7 @@ protected function getInstance($options = [])
         return new RedisHandler(new AppConfig(), $this->userIpAddress);
     }
 
-    public function testSavePathWithoutProtocol()
+    public function testSavePathWithoutProtocol(): void
     {
         $handler = $this->getInstance(
             ['savePath' => '127.0.0.1:6379']
@@ -64,7 +64,7 @@ public function testSavePathWithoutProtocol()
         $this->assertSame('tcp', $savePath['protocol']);
     }
 
-    public function testSavePathTLSAuth()
+    public function testSavePathTLSAuth(): void
     {
         $handler = $this->getInstance(
             ['savePath' => 'tls://127.0.0.1:6379?auth=password']
@@ -76,7 +76,7 @@ public function testSavePathTLSAuth()
         $this->assertSame('password', $savePath['password']);
     }
 
-    public function testSavePathTCPAuth()
+    public function testSavePathTCPAuth(): void
     {
         $handler = $this->getInstance(
             ['savePath' => 'tcp://127.0.0.1:6379?auth=password']
@@ -88,7 +88,7 @@ public function testSavePathTCPAuth()
         $this->assertSame('password', $savePath['password']);
     }
 
-    public function testSavePathTimeoutFloat()
+    public function testSavePathTimeoutFloat(): void
     {
         $handler = $this->getInstance(
             ['savePath' => 'tcp://127.0.0.1:6379?timeout=2.5']
@@ -99,7 +99,7 @@ public function testSavePathTimeoutFloat()
         $this->assertSame(2.5, $savePath['timeout']);
     }
 
-    public function testSavePathTimeoutInt()
+    public function testSavePathTimeoutInt(): void
     {
         $handler = $this->getInstance(
             ['savePath' => 'tcp://127.0.0.1:6379?timeout=10']
@@ -110,13 +110,13 @@ public function testSavePathTimeoutInt()
         $this->assertSame(10.0, $savePath['timeout']);
     }
 
-    public function testOpen()
+    public function testOpen(): void
     {
         $handler = $this->getInstance();
         $this->assertTrue($handler->open($this->sessionSavePath, $this->sessionName));
     }
 
-    public function testOpenWithDefaultProtocol()
+    public function testOpenWithDefaultProtocol(): void
     {
         $default = $this->sessionSavePath;
 
@@ -129,7 +129,7 @@ public function testOpenWithDefaultProtocol()
         $this->sessionSavePath = $default;
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         $handler = $this->getInstance();
         $handler->open($this->sessionSavePath, $this->sessionName);
@@ -143,7 +143,7 @@ public function testWrite()
         $handler->close();
     }
 
-    public function testReadSuccess()
+    public function testReadSuccess(): void
     {
         $handler = $this->getInstance();
         $handler->open($this->sessionSavePath, $this->sessionName);
@@ -156,7 +156,7 @@ public function testReadSuccess()
         $handler->close();
     }
 
-    public function testReadFailure()
+    public function testReadFailure(): void
     {
         $handler = $this->getInstance();
         $handler->open($this->sessionSavePath, $this->sessionName);
@@ -166,7 +166,7 @@ public function testReadFailure()
         $handler->close();
     }
 
-    public function testGC()
+    public function testGC(): void
     {
         $handler = $this->getInstance();
         $this->assertSame(1, $handler->gc(3600));
diff --git a/tests/system/Session/SessionTest.php b/tests/system/Session/SessionTest.php
index 8e0170d0fee1..178102cdb36c 100644
--- a/tests/system/Session/SessionTest.php
+++ b/tests/system/Session/SessionTest.php
@@ -68,7 +68,7 @@ protected function getInstance($options = [])
         return $session;
     }
 
-    public function testSessionSetsRegenerateTime()
+    public function testSessionSetsRegenerateTime(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -76,7 +76,7 @@ public function testSessionSetsRegenerateTime()
         $this->assertTrue(isset($_SESSION['__ci_last_regenerate']) && ! empty($_SESSION['__ci_last_regenerate']));
     }
 
-    public function testWillRegenerateSessionAutomatically()
+    public function testWillRegenerateSessionAutomatically(): void
     {
         $session = $this->getInstance();
 
@@ -88,7 +88,7 @@ public function testWillRegenerateSessionAutomatically()
         $this->assertGreaterThan($time + 90, $_SESSION['__ci_last_regenerate']);
     }
 
-    public function testCanSetSingleValue()
+    public function testCanSetSingleValue(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -98,7 +98,7 @@ public function testCanSetSingleValue()
         $this->assertSame('bar', $_SESSION['foo']);
     }
 
-    public function testCanSetArray()
+    public function testCanSetArray(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -116,7 +116,7 @@ public function testCanSetArray()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1492
      */
-    public function testCanSerializeArray()
+    public function testCanSerializeArray(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -131,7 +131,7 @@ public function testCanSerializeArray()
         $this->assertSame($locations, $session->get('_ci_old_input')['location']);
     }
 
-    public function testGetSimpleKey()
+    public function testGetSimpleKey(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -141,7 +141,7 @@ public function testGetSimpleKey()
         $this->assertSame('bar', $session->get('foo'));
     }
 
-    public function testGetReturnsNullWhenNotFound()
+    public function testGetReturnsNullWhenNotFound(): void
     {
         $_SESSION = [];
 
@@ -151,7 +151,7 @@ public function testGetReturnsNullWhenNotFound()
         $this->assertNull($session->get('foo'));
     }
 
-    public function testGetReturnsNullWhenNotFoundWithXmlHttpRequest()
+    public function testGetReturnsNullWhenNotFoundWithXmlHttpRequest(): void
     {
         $_SERVER['HTTP_X_REQUESTED_WITH'] = 'xmlhttprequest';
         $_SESSION                         = [];
@@ -162,7 +162,7 @@ public function testGetReturnsNullWhenNotFoundWithXmlHttpRequest()
         $this->assertNull($session->get('foo'));
     }
 
-    public function testGetReturnsEmptyArrayWhenWithXmlHttpRequest()
+    public function testGetReturnsEmptyArrayWhenWithXmlHttpRequest(): void
     {
         $_SERVER['HTTP_X_REQUESTED_WITH'] = 'xmlhttprequest';
         $_SESSION                         = [];
@@ -173,7 +173,7 @@ public function testGetReturnsEmptyArrayWhenWithXmlHttpRequest()
         $this->assertSame([], $session->get());
     }
 
-    public function testGetReturnsItemValueisZero()
+    public function testGetReturnsItemValueisZero(): void
     {
         $_SESSION = [];
 
@@ -185,7 +185,7 @@ public function testGetReturnsItemValueisZero()
         $this->assertSame(0, $session->get('foo'));
     }
 
-    public function testGetReturnsAllWithNoKeys()
+    public function testGetReturnsAllWithNoKeys(): void
     {
         $_SESSION = [
             'foo' => 'bar',
@@ -201,7 +201,7 @@ public function testGetReturnsAllWithNoKeys()
         $this->assertArrayHasKey('bar', $result);
     }
 
-    public function testGetAsProperty()
+    public function testGetAsProperty(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -211,7 +211,7 @@ public function testGetAsProperty()
         $this->assertSame('bar', $session->foo);
     }
 
-    public function testGetAsNormal()
+    public function testGetAsNormal(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -221,7 +221,7 @@ public function testGetAsNormal()
         $this->assertSame('bar', $_SESSION['foo']);
     }
 
-    public function testHasReturnsTrueOnSuccess()
+    public function testHasReturnsTrueOnSuccess(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -231,7 +231,7 @@ public function testHasReturnsTrueOnSuccess()
         $this->assertTrue($session->has('foo'));
     }
 
-    public function testHasReturnsFalseOnNotFound()
+    public function testHasReturnsFalseOnNotFound(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -241,7 +241,7 @@ public function testHasReturnsFalseOnNotFound()
         $this->assertFalse($session->has('bar'));
     }
 
-    public function testIssetReturnsTrueOnSuccess()
+    public function testIssetReturnsTrueOnSuccess(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -252,7 +252,7 @@ public function testIssetReturnsTrueOnSuccess()
         $this->assertTrue($issetReturn);
     }
 
-    public function testIssetReturnsFalseOnNotFound()
+    public function testIssetReturnsFalseOnNotFound(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -263,7 +263,7 @@ public function testIssetReturnsFalseOnNotFound()
         $this->assertFalse($issetReturn);
     }
 
-    public function testPushNewValueIntoArraySessionValue()
+    public function testPushNewValueIntoArraySessionValue(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -280,7 +280,7 @@ public function testPushNewValueIntoArraySessionValue()
         );
     }
 
-    public function testRemoveActuallyRemoves()
+    public function testRemoveActuallyRemoves(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -292,7 +292,7 @@ public function testRemoveActuallyRemoves()
         $this->assertFalse($session->has('foo'));
     }
 
-    public function testHasReturnsCanRemoveArray()
+    public function testHasReturnsCanRemoveArray(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -310,7 +310,7 @@ public function testHasReturnsCanRemoveArray()
         $this->assertArrayNotHasKey('bar', $_SESSION);
     }
 
-    public function testSetMagicMethod()
+    public function testSetMagicMethod(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -321,7 +321,7 @@ public function testSetMagicMethod()
         $this->assertSame('bar', $_SESSION['foo']);
     }
 
-    public function testCanFlashData()
+    public function testCanFlashData(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -343,7 +343,7 @@ public function testCanFlashData()
         $this->assertFalse($session->has('foo'));
     }
 
-    public function testCanFlashArray()
+    public function testCanFlashArray(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -359,7 +359,7 @@ public function testCanFlashArray()
         $this->assertSame('new', $_SESSION['__ci_vars']['bar']);
     }
 
-    public function testKeepFlashData()
+    public function testKeepFlashData(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -386,7 +386,7 @@ public function testKeepFlashData()
         $this->assertSame('old', $_SESSION['__ci_vars']['foo']);
     }
 
-    public function testUnmarkFlashDataRemovesData()
+    public function testUnmarkFlashDataRemovesData(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -406,7 +406,7 @@ public function testUnmarkFlashDataRemovesData()
         $this->assertFalse($issetReturn);
     }
 
-    public function testGetFlashKeysOnlyReturnsFlashKeys()
+    public function testGetFlashKeysOnlyReturnsFlashKeys(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -420,7 +420,7 @@ public function testGetFlashKeysOnlyReturnsFlashKeys()
         $this->assertNotContains('bar', $keys);
     }
 
-    public function testSetTempDataWorks()
+    public function testSetTempDataWorks(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -429,7 +429,7 @@ public function testSetTempDataWorks()
         $this->assertGreaterThanOrEqual($_SESSION['__ci_vars']['foo'], time() + 300);
     }
 
-    public function testSetTempDataArrayMultiTTL()
+    public function testSetTempDataArrayMultiTTL(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -447,7 +447,7 @@ public function testSetTempDataArrayMultiTTL()
         $this->assertLessThanOrEqual($_SESSION['__ci_vars']['baz'], $time + 100);
     }
 
-    public function testSetTempDataArraySingleTTL()
+    public function testSetTempDataArraySingleTTL(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -461,7 +461,7 @@ public function testSetTempDataArraySingleTTL()
         $this->assertLessThanOrEqual($_SESSION['__ci_vars']['baz'], $time + 200);
     }
 
-    public function testGetTestDataReturnsAll()
+    public function testGetTestDataReturnsAll(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -477,7 +477,7 @@ public function testGetTestDataReturnsAll()
         $this->assertSame($data, $session->getTempdata());
     }
 
-    public function testGetTestDataReturnsSingle()
+    public function testGetTestDataReturnsSingle(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -492,7 +492,7 @@ public function testGetTestDataReturnsSingle()
         $this->assertSame('bar', $session->getTempdata('foo'));
     }
 
-    public function testRemoveTempDataActuallyDeletes()
+    public function testRemoveTempDataActuallyDeletes(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -508,7 +508,7 @@ public function testRemoveTempDataActuallyDeletes()
         $this->assertSame(['bar' => 'baz'], $session->getTempdata());
     }
 
-    public function testUnMarkTempDataSingle()
+    public function testUnMarkTempDataSingle(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -524,7 +524,7 @@ public function testUnMarkTempDataSingle()
         $this->assertSame(['bar' => 'baz'], $session->getTempdata());
     }
 
-    public function testUnMarkTempDataArray()
+    public function testUnMarkTempDataArray(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -540,7 +540,7 @@ public function testUnMarkTempDataArray()
         $this->assertSame([], $session->getTempdata());
     }
 
-    public function testGetTempdataKeys()
+    public function testGetTempdataKeys(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -556,7 +556,7 @@ public function testGetTempdataKeys()
         $this->assertSame(['foo', 'bar'], $session->getTempKeys());
     }
 
-    public function testGetDotKey()
+    public function testGetDotKey(): void
     {
         $session = $this->getInstance();
         $session->start();
@@ -564,7 +564,7 @@ public function testGetDotKey()
         $this->assertSame('value', $session->get('test.1'));
     }
 
-    public function testLaxSameSite()
+    public function testLaxSameSite(): void
     {
         $config           = new CookieConfig();
         $config->samesite = 'Lax';
@@ -577,7 +577,7 @@ public function testLaxSameSite()
         $this->assertSame('Lax', $cookies[0]->getSameSite());
     }
 
-    public function testNoneSameSite()
+    public function testNoneSameSite(): void
     {
         $config           = new CookieConfig();
         $config->secure   = true;
@@ -593,7 +593,7 @@ public function testNoneSameSite()
         $this->assertSame('None', $cookies[0]->getSameSite());
     }
 
-    public function testNoSameSiteReturnsDefault()
+    public function testNoSameSiteReturnsDefault(): void
     {
         $config           = new CookieConfig();
         $config->samesite = '';
@@ -608,7 +608,7 @@ public function testNoSameSiteReturnsDefault()
         $this->assertSame('Lax', $cookies[0]->getSameSite());
     }
 
-    public function testInvalidSameSite()
+    public function testInvalidSameSite(): void
     {
         $this->expectException(CookieException::class);
         $this->expectExceptionMessage(lang('Cookie.invalidSameSite', ['Invalid']));
@@ -622,7 +622,7 @@ public function testInvalidSameSite()
         $session->start();
     }
 
-    public function testExpires()
+    public function testExpires(): void
     {
         $session = $this->getInstance(['expiration' => 8000]);
         $session->start();
@@ -632,7 +632,7 @@ public function testExpires()
         $this->assertGreaterThan(8000, $cookies[0]->getExpiresTimestamp());
     }
 
-    public function testExpiresOnClose()
+    public function testExpiresOnClose(): void
     {
         $session = $this->getInstance(['expiration' => 0]);
         $session->start();
diff --git a/tests/system/SparkTest.php b/tests/system/SparkTest.php
index a391689c2719..8467f8715002 100644
--- a/tests/system/SparkTest.php
+++ b/tests/system/SparkTest.php
@@ -20,7 +20,7 @@
  */
 final class SparkTest extends CIUnitTestCase
 {
-    public function testCanUseOption()
+    public function testCanUseOption(): void
     {
         ob_start();
         passthru('php spark list --simple');
diff --git a/tests/system/Test/BootstrapFCPATHTest.php b/tests/system/Test/BootstrapFCPATHTest.php
index 8ae25a0e3145..7bd5b81d75d6 100644
--- a/tests/system/Test/BootstrapFCPATHTest.php
+++ b/tests/system/Test/BootstrapFCPATHTest.php
@@ -47,7 +47,7 @@ protected function tearDown(): void
         $this->deleteDirectories();
     }
 
-    public function testSetFCPATH()
+    public function testSetFCPATH(): void
     {
         $result1     = $this->readOutput($this->file1);
         $correctPath = $this->correctFCPATH();
diff --git a/tests/system/Test/ControllerTestTraitTest.php b/tests/system/Test/ControllerTestTraitTest.php
index de8e8fbc4777..b5d08e72ed8f 100644
--- a/tests/system/Test/ControllerTestTraitTest.php
+++ b/tests/system/Test/ControllerTestTraitTest.php
@@ -36,7 +36,7 @@ final class ControllerTestTraitTest extends CIUnitTestCase
 {
     use ControllerTestTrait;
 
-    public function testBadController()
+    public function testBadController(): void
     {
         $this->expectException('InvalidArgumentException');
         $logger = new Logger(new LoggerConfig());
@@ -46,7 +46,7 @@ public function testBadController()
             ->execute('index');
     }
 
-    public function testBadControllerMethod()
+    public function testBadControllerMethod(): void
     {
         $this->expectException('InvalidArgumentException');
         $logger = new Logger(new LoggerConfig());
@@ -56,7 +56,7 @@ public function testBadControllerMethod()
             ->execute('nothere');
     }
 
-    public function testController()
+    public function testController(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -67,7 +67,7 @@ public function testController()
         $this->assertTrue($result->isOK());
     }
 
-    public function testControllerWithoutLogger()
+    public function testControllerWithoutLogger(): void
     {
         $result = $this->withURI('http://example.com')
             ->controller(Home::class)
@@ -76,7 +76,7 @@ public function testControllerWithoutLogger()
         $this->assertTrue($result->isOK());
     }
 
-    public function testPopcornIndex()
+    public function testPopcornIndex(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -87,7 +87,7 @@ public function testPopcornIndex()
         $this->assertTrue($result->isOK());
     }
 
-    public function testPopcornIndex2()
+    public function testPopcornIndex2(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -99,7 +99,7 @@ public function testPopcornIndex2()
         $this->assertSame('Hi there', $body);
     }
 
-    public function testPopcornFailure()
+    public function testPopcornFailure(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -110,7 +110,7 @@ public function testPopcornFailure()
         $this->assertSame(567, $result->response()->getStatusCode());
     }
 
-    public function testPopcornException()
+    public function testPopcornException(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -121,7 +121,7 @@ public function testPopcornException()
         $this->assertSame(500, $result->response()->getStatusCode());
     }
 
-    public function testPopcornIndexWithSupport()
+    public function testPopcornIndexWithSupport(): void
     {
         $logger = new Logger(new LoggerConfig());
         $config = new App();
@@ -140,7 +140,7 @@ public function testPopcornIndexWithSupport()
         $this->assertSame('Hi there', $body);
     }
 
-    public function testRequestPassthrough()
+    public function testRequestPassthrough(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -152,7 +152,7 @@ public function testRequestPassthrough()
         $this->assertSame('get', $req->getMethod());
     }
 
-    public function testFailureResponse()
+    public function testFailureResponse(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -164,7 +164,7 @@ public function testFailureResponse()
         $this->assertSame(401, $result->response()->getStatusCode());
     }
 
-    public function testEmptyResponse()
+    public function testEmptyResponse(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -177,7 +177,7 @@ public function testEmptyResponse()
         $this->assertFalse($result->isOK());
     }
 
-    public function testRedirect()
+    public function testRedirect(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -188,7 +188,7 @@ public function testRedirect()
         $this->assertTrue($result->isRedirect());
     }
 
-    public function testDOMParserForward()
+    public function testDOMParserForward(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -199,7 +199,7 @@ public function testDOMParserForward()
         $this->assertTrue($result->see('Hi'));
     }
 
-    public function testFailsForward()
+    public function testFailsForward(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withURI('http://example.com')
@@ -214,7 +214,7 @@ public function testFailsForward()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/1834
      */
-    public function testResponseOverriding()
+    public function testResponseOverriding(): void
     {
         $result = $this->withURI('http://example.com/rest/')
             ->controller(Popcorn::class)
@@ -227,7 +227,7 @@ public function testResponseOverriding()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/2470
      */
-    public function testControllerNoURI()
+    public function testControllerNoURI(): void
     {
         $logger = new Logger(new LoggerConfig());
         $result = $this->withLogger($logger)
@@ -237,14 +237,14 @@ public function testControllerNoURI()
         $this->assertTrue($result->isOK());
     }
 
-    public function testRedirectRoute()
+    public function testRedirectRoute(): void
     {
         $result = $this->controller(Popcorn::class)
             ->execute('toindex');
         $this->assertTrue($result->isRedirect());
     }
 
-    public function testUsesRequestBody()
+    public function testUsesRequestBody(): void
     {
         $this->controller = new class () extends Controller {
             public function throwsBody(): void
diff --git a/tests/system/Test/DOMParserTest.php b/tests/system/Test/DOMParserTest.php
index 49d5e4b5d955..56c3cc00b31e 100644
--- a/tests/system/Test/DOMParserTest.php
+++ b/tests/system/Test/DOMParserTest.php
@@ -27,7 +27,7 @@ protected function setUp(): void
         }
     }
 
-    public function testCanRoundTripHTML()
+    public function testCanRoundTripHTML(): void
     {
         $dom = new DOMParser();
 
@@ -38,7 +38,7 @@ public function testCanRoundTripHTML()
         $this->assertSame($expected . "\n", $dom->withString($html)->getBody());
     }
 
-    public function testParseSelectorWithID()
+    public function testParseSelectorWithID(): void
     {
         $dom = new DOMParser();
 
@@ -48,7 +48,7 @@ public function testParseSelectorWithID()
         $this->assertSame('row', $selector['id']);
     }
 
-    public function testParseSelectorWithClass()
+    public function testParseSelectorWithClass(): void
     {
         $dom = new DOMParser();
 
@@ -58,7 +58,7 @@ public function testParseSelectorWithClass()
         $this->assertSame('row', $selector['class']);
     }
 
-    public function testParseSelectorWithClassMultiple()
+    public function testParseSelectorWithClassMultiple(): void
     {
         $dom = new DOMParser();
 
@@ -69,7 +69,7 @@ public function testParseSelectorWithClassMultiple()
         $this->assertSame('row', $selector['class']);
     }
 
-    public function testParseSelectorWithAttribute()
+    public function testParseSelectorWithAttribute(): void
     {
         $dom = new DOMParser();
 
@@ -93,7 +93,7 @@ public function provideText(): iterable
      *
      * @param mixed $text
      */
-    public function testSeeText($text)
+    public function testSeeText($text): void
     {
         $dom = new DOMParser();
 
@@ -103,7 +103,7 @@ public function testSeeText($text)
         $this->assertTrue($dom->see($text));
     }
 
-    public function testSeeHTML()
+    public function testSeeHTML(): void
     {
         $dom = new DOMParser();
 
@@ -116,7 +116,7 @@ public function testSeeHTML()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3984
      */
-    public function testSeeHTMLOutsideBodyTag()
+    public function testSeeHTMLOutsideBodyTag(): void
     {
         $dom = new DOMParser();
 
@@ -126,7 +126,7 @@ public function testSeeHTMLOutsideBodyTag()
         $this->assertTrue($dom->see('My Title', 'title'));
     }
 
-    public function testSeeFail()
+    public function testSeeFail(): void
     {
         $dom = new DOMParser();
 
@@ -141,7 +141,7 @@ public function testSeeFail()
      *
      * @param mixed $text
      */
-    public function testSeeElement($text)
+    public function testSeeElement($text): void
     {
         $dom = new DOMParser();
 
@@ -151,7 +151,7 @@ public function testSeeElement($text)
         $this->assertTrue($dom->see($text, 'h1'));
     }
 
-    public function testSeeElementPartialText()
+    public function testSeeElementPartialText(): void
     {
         $dom = new DOMParser();
 
@@ -161,7 +161,7 @@ public function testSeeElementPartialText()
         $this->assertTrue($dom->see('Hello World', 'h1'));
     }
 
-    public function testSeeElementID()
+    public function testSeeElementID(): void
     {
         $dom = new DOMParser();
 
@@ -171,7 +171,7 @@ public function testSeeElementID()
         $this->assertTrue($dom->see('Hello World', '#heading'));
     }
 
-    public function testSeeElementIDFails()
+    public function testSeeElementIDFails(): void
     {
         $dom = new DOMParser();
 
@@ -181,7 +181,7 @@ public function testSeeElementIDFails()
         $this->assertFalse($dom->see('Hello Worlds', '#heading'));
     }
 
-    public function testSeeElementIDWithTag()
+    public function testSeeElementIDWithTag(): void
     {
         $dom = new DOMParser();
 
@@ -191,7 +191,7 @@ public function testSeeElementIDWithTag()
         $this->assertTrue($dom->see('Hello World', 'h1#heading'));
     }
 
-    public function testSeeElementIDWithTagFails()
+    public function testSeeElementIDWithTagFails(): void
     {
         $dom = new DOMParser();
 
@@ -201,7 +201,7 @@ public function testSeeElementIDWithTagFails()
         $this->assertFalse($dom->see('Hello World', 'h1#heading'));
     }
 
-    public function testSeeElementClass()
+    public function testSeeElementClass(): void
     {
         $dom = new DOMParser();
 
@@ -211,7 +211,7 @@ public function testSeeElementClass()
         $this->assertTrue($dom->see('Hello World', '.heading'));
     }
 
-    public function testSeeElementClassFail()
+    public function testSeeElementClassFail(): void
     {
         $dom = new DOMParser();
 
@@ -221,7 +221,7 @@ public function testSeeElementClassFail()
         $this->assertFalse($dom->see('Hello World', '.heading'));
     }
 
-    public function testSeeElementClassWithTag()
+    public function testSeeElementClassWithTag(): void
     {
         $dom = new DOMParser();
 
@@ -231,7 +231,7 @@ public function testSeeElementClassWithTag()
         $this->assertTrue($dom->see('Hello World', 'h1.heading'));
     }
 
-    public function testSeeElementClassWithTagFail()
+    public function testSeeElementClassWithTagFail(): void
     {
         $dom = new DOMParser();
 
@@ -241,7 +241,7 @@ public function testSeeElementClassWithTagFail()
         $this->assertFalse($dom->see('Hello World', 'h2.heading'));
     }
 
-    public function testSeeElementSuccess()
+    public function testSeeElementSuccess(): void
     {
         $dom = new DOMParser();
 
@@ -251,7 +251,7 @@ public function testSeeElementSuccess()
         $this->assertTrue($dom->seeElement('#heading'));
     }
 
-    public function testSeeElementFail()
+    public function testSeeElementFail(): void
     {
         $dom = new DOMParser();
 
@@ -261,7 +261,7 @@ public function testSeeElementFail()
         $this->assertFalse($dom->seeElement('#headings'));
     }
 
-    public function testDontSeeElementSuccess()
+    public function testDontSeeElementSuccess(): void
     {
         $dom = new DOMParser();
 
@@ -271,7 +271,7 @@ public function testDontSeeElementSuccess()
         $this->assertTrue($dom->dontSeeElement('#head'));
     }
 
-    public function testDontSeeElementFail()
+    public function testDontSeeElementFail(): void
     {
         $dom = new DOMParser();
 
@@ -281,7 +281,7 @@ public function testDontSeeElementFail()
         $this->assertFalse($dom->dontSeeElement('#heading'));
     }
 
-    public function testSeeLinkSuccess()
+    public function testSeeLinkSuccess(): void
     {
         $dom = new DOMParser();
 
@@ -291,7 +291,7 @@ public function testSeeLinkSuccess()
         $this->assertTrue($dom->seeLink('Hello'));
     }
 
-    public function testSeeLinkFalse()
+    public function testSeeLinkFalse(): void
     {
         $dom = new DOMParser();
 
@@ -301,7 +301,7 @@ public function testSeeLinkFalse()
         $this->assertFalse($dom->seeLink('Hello World!'));
     }
 
-    public function testSeeLinkClassSuccess()
+    public function testSeeLinkClassSuccess(): void
     {
         $dom = new DOMParser();
 
@@ -311,7 +311,7 @@ public function testSeeLinkClassSuccess()
         $this->assertTrue($dom->seeLink('Hello', '.btn'));
     }
 
-    public function testSeeLinkClassFail()
+    public function testSeeLinkClassFail(): void
     {
         $dom = new DOMParser();
 
@@ -321,7 +321,7 @@ public function testSeeLinkClassFail()
         $this->assertFalse($dom->seeLink('Hello', '.btn'));
     }
 
-    public function testSeeInFieldSuccess()
+    public function testSeeInFieldSuccess(): void
     {
         $dom = new DOMParser();
 
@@ -331,7 +331,7 @@ public function testSeeInFieldSuccess()
         $this->assertTrue($dom->seeInField('user', 'Foobar'));
     }
 
-    public function testSeeInFieldFail()
+    public function testSeeInFieldFail(): void
     {
         $dom = new DOMParser();
 
@@ -341,7 +341,7 @@ public function testSeeInFieldFail()
         $this->assertFalse($dom->seeInField('user', 'Foobars'));
     }
 
-    public function testSeeInFieldSuccessArray()
+    public function testSeeInFieldSuccessArray(): void
     {
         $dom = new DOMParser();
 
@@ -351,7 +351,7 @@ public function testSeeInFieldSuccessArray()
         $this->assertTrue($dom->seeInField('user[name]', 'Foobar'));
     }
 
-    public function testSeeCheckboxIsCheckedByIDTrue()
+    public function testSeeCheckboxIsCheckedByIDTrue(): void
     {
         $dom = new DOMParser();
 
@@ -361,7 +361,7 @@ public function testSeeCheckboxIsCheckedByIDTrue()
         $this->assertTrue($dom->seeCheckboxIsChecked('#user'));
     }
 
-    public function testSeeCheckboxIsCheckedByIDFail()
+    public function testSeeCheckboxIsCheckedByIDFail(): void
     {
         $dom = new DOMParser();
 
@@ -371,7 +371,7 @@ public function testSeeCheckboxIsCheckedByIDFail()
         $this->assertFalse($dom->seeCheckboxIsChecked('#user'));
     }
 
-    public function testSeeCheckboxIsCheckedByClassTrue()
+    public function testSeeCheckboxIsCheckedByClassTrue(): void
     {
         $dom = new DOMParser();
 
@@ -381,7 +381,7 @@ public function testSeeCheckboxIsCheckedByClassTrue()
         $this->assertTrue($dom->seeCheckboxIsChecked('.btn'));
     }
 
-    public function testWithFile()
+    public function testWithFile(): void
     {
         $dom = new DOMParser();
 
@@ -391,7 +391,7 @@ public function testWithFile()
         $this->assertTrue($dom->see('Directory access is forbidden.'));
     }
 
-    public function testWithNotFile()
+    public function testWithNotFile(): void
     {
         $dom = new DOMParser();
 
@@ -401,7 +401,7 @@ public function testWithNotFile()
         $dom->withFile($filename);
     }
 
-    public function testSeeAttribute()
+    public function testSeeAttribute(): void
     {
         $dom = new DOMParser();
 
diff --git a/tests/system/Test/FabricatorTest.php b/tests/system/Test/FabricatorTest.php
index 6f92be2aaaad..8242f629e0ab 100644
--- a/tests/system/Test/FabricatorTest.php
+++ b/tests/system/Test/FabricatorTest.php
@@ -42,14 +42,14 @@ protected function tearDown(): void
         Fabricator::resetCounts();
     }
 
-    public function testConstructorWithString()
+    public function testConstructorWithString(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
         $this->assertInstanceOf(Fabricator::class, $fabricator);
     }
 
-    public function testConstructorWithInstance()
+    public function testConstructorWithInstance(): void
     {
         $model = new UserModel();
 
@@ -58,7 +58,7 @@ public function testConstructorWithInstance()
         $this->assertInstanceOf(Fabricator::class, $fabricator);
     }
 
-    public function testConstructorWithInvalid()
+    public function testConstructorWithInvalid(): void
     {
         $this->expectException('InvalidArgumentException');
         $this->expectExceptionMessage(lang('Fabricator.invalidModel'));
@@ -66,28 +66,28 @@ public function testConstructorWithInvalid()
         new Fabricator('SillyRabbit\Models\AreForKids');
     }
 
-    public function testConstructorSetsFormatters()
+    public function testConstructorSetsFormatters(): void
     {
         $fabricator = new Fabricator(UserModel::class, $this->formatters);
 
         $this->assertSame($this->formatters, $fabricator->getFormatters());
     }
 
-    public function testConstructorGuessesFormatters()
+    public function testConstructorGuessesFormatters(): void
     {
         $fabricator = new Fabricator(UserModel::class, null);
 
         $this->assertSame($this->formatters, $fabricator->getFormatters());
     }
 
-    public function testConstructorDefaultsToAppLocale()
+    public function testConstructorDefaultsToAppLocale(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
         $this->assertSame(config('App')->defaultLocale, $fabricator->getLocale());
     }
 
-    public function testConstructorUsesProvidedLocale()
+    public function testConstructorUsesProvidedLocale(): void
     {
         $locale = 'fr_FR';
 
@@ -96,7 +96,7 @@ public function testConstructorUsesProvidedLocale()
         $this->assertSame($locale, $fabricator->getLocale());
     }
 
-    public function testModelUsesNewInstance()
+    public function testModelUsesNewInstance(): void
     {
         // Inject the wrong model for UserModel to show it is ignored by Fabricator
         $mock = new FabricatorModel();
@@ -106,7 +106,7 @@ public function testModelUsesNewInstance()
         $this->assertInstanceOf(UserModel::class, $fabricator->getModel());
     }
 
-    public function testGetModelReturnsModel()
+    public function testGetModelReturnsModel(): void
     {
         $fabricator = new Fabricator(UserModel::class);
         $this->assertInstanceOf(UserModel::class, $fabricator->getModel());
@@ -116,7 +116,7 @@ public function testGetModelReturnsModel()
         $this->assertInstanceOf(UserModel::class, $fabricator2->getModel());
     }
 
-    public function testGetFakerReturnsUsableGenerator()
+    public function testGetFakerReturnsUsableGenerator(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -125,7 +125,7 @@ public function testGetFakerReturnsUsableGenerator()
         $this->assertIsNumeric($faker->randomDigit());
     }
 
-    public function testSetFormattersChangesFormatters()
+    public function testSetFormattersChangesFormatters(): void
     {
         $formatters = ['boo' => 'hiss'];
         $fabricator = new Fabricator(UserModel::class);
@@ -135,7 +135,7 @@ public function testSetFormattersChangesFormatters()
         $this->assertSame($formatters, $fabricator->getFormatters());
     }
 
-    public function testSetFormattersDetectsFormatters()
+    public function testSetFormattersDetectsFormatters(): void
     {
         $formatters = ['boo' => 'hiss'];
         $fabricator = new Fabricator(UserModel::class, $formatters);
@@ -145,7 +145,7 @@ public function testSetFormattersDetectsFormatters()
         $this->assertSame($this->formatters, $fabricator->getFormatters());
     }
 
-    public function testDetectFormattersDetectsFormatters()
+    public function testDetectFormattersDetectsFormatters(): void
     {
         $formatters = ['boo' => 'hiss'];
         $fabricator = new Fabricator(UserModel::class, $formatters);
@@ -157,7 +157,7 @@ public function testDetectFormattersDetectsFormatters()
         $this->assertSame($this->formatters, $fabricator->getFormatters());
     }
 
-    public function testSetOverridesSets()
+    public function testSetOverridesSets(): void
     {
         $overrides  = ['name' => 'Steve'];
         $fabricator = new Fabricator(UserModel::class);
@@ -167,7 +167,7 @@ public function testSetOverridesSets()
         $this->assertSame($overrides, $fabricator->getOverrides());
     }
 
-    public function testSetOverridesDefaultPersists()
+    public function testSetOverridesDefaultPersists(): void
     {
         $overrides  = ['name' => 'Steve'];
         $fabricator = new Fabricator(UserModel::class);
@@ -178,7 +178,7 @@ public function testSetOverridesDefaultPersists()
         $this->assertSame($overrides, $fabricator->getOverrides());
     }
 
-    public function testSetOverridesOnce()
+    public function testSetOverridesOnce(): void
     {
         $overrides  = ['name' => 'Steve'];
         $fabricator = new Fabricator(UserModel::class);
@@ -189,7 +189,7 @@ public function testSetOverridesOnce()
         $this->assertSame([], $fabricator->getOverrides());
     }
 
-    public function testGuessFormattersReturnsActual()
+    public function testGuessFormattersReturnsActual(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -201,7 +201,7 @@ public function testGuessFormattersReturnsActual()
         $this->assertSame($field, $formatter);
     }
 
-    public function testGuessFormattersFieldReturnsDateFormat()
+    public function testGuessFormattersFieldReturnsDateFormat(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -213,7 +213,7 @@ public function testGuessFormattersFieldReturnsDateFormat()
         $this->assertSame('date', $formatter);
     }
 
-    public function testGuessFormattersPrimaryReturnsNumberBetween()
+    public function testGuessFormattersPrimaryReturnsNumberBetween(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -225,7 +225,7 @@ public function testGuessFormattersPrimaryReturnsNumberBetween()
         $this->assertSame('numberBetween', $formatter);
     }
 
-    public function testGuessFormattersMatchesPartial()
+    public function testGuessFormattersMatchesPartial(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -237,7 +237,7 @@ public function testGuessFormattersMatchesPartial()
         $this->assertSame('email', $formatter);
     }
 
-    public function testGuessFormattersFallback()
+    public function testGuessFormattersFallback(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -249,7 +249,7 @@ public function testGuessFormattersFallback()
         $this->assertSame($fabricator->defaultFormatter, $formatter);
     }
 
-    public function testMakeArrayReturnsArray()
+    public function testMakeArrayReturnsArray(): void
     {
         $fabricator = new Fabricator(UserModel::class, $this->formatters);
 
@@ -258,7 +258,7 @@ public function testMakeArrayReturnsArray()
         $this->assertIsArray($result);
     }
 
-    public function testMakeArrayUsesOverrides()
+    public function testMakeArrayUsesOverrides(): void
     {
         $overrides = ['name' => 'The Admiral'];
 
@@ -270,7 +270,7 @@ public function testMakeArrayUsesOverrides()
         $this->assertSame($overrides['name'], $result['name']);
     }
 
-    public function testMakeArrayReturnsValidData()
+    public function testMakeArrayReturnsValidData(): void
     {
         $fabricator = new Fabricator(UserModel::class, $this->formatters);
 
@@ -279,7 +279,7 @@ public function testMakeArrayReturnsValidData()
         $this->assertSame($result['email'], filter_var($result['email'], FILTER_VALIDATE_EMAIL));
     }
 
-    public function testMakeArrayUsesFakeMethod()
+    public function testMakeArrayUsesFakeMethod(): void
     {
         $fabricator = new Fabricator(FabricatorModel::class);
 
@@ -288,7 +288,7 @@ public function testMakeArrayUsesFakeMethod()
         $this->assertSame($result['name'], filter_var($result['name'], FILTER_VALIDATE_IP));
     }
 
-    public function testMakeObjectReturnsModelReturnType()
+    public function testMakeObjectReturnsModelReturnType(): void
     {
         $fabricator = new Fabricator(EntityModel::class);
         $expected   = $fabricator->getModel()->returnType;
@@ -298,7 +298,7 @@ public function testMakeObjectReturnsModelReturnType()
         $this->assertInstanceOf($expected, $result);
     }
 
-    public function testMakeObjectReturnsProvidedClass()
+    public function testMakeObjectReturnsProvidedClass(): void
     {
         $fabricator = new Fabricator(UserModel::class, $this->formatters);
         $className  = SimpleEntity::class;
@@ -308,7 +308,7 @@ public function testMakeObjectReturnsProvidedClass()
         $this->assertInstanceOf($className, $result);
     }
 
-    public function testMakeObjectReturnsStdClassForArrayReturnType()
+    public function testMakeObjectReturnsStdClassForArrayReturnType(): void
     {
         $fabricator = new Fabricator(EventModel::class);
 
@@ -317,7 +317,7 @@ public function testMakeObjectReturnsStdClassForArrayReturnType()
         $this->assertInstanceOf('stdClass', $result);
     }
 
-    public function testMakeObjectReturnsStdClassForObjectReturnType()
+    public function testMakeObjectReturnsStdClassForObjectReturnType(): void
     {
         $fabricator = new Fabricator(UserModel::class, $this->formatters);
 
@@ -326,7 +326,7 @@ public function testMakeObjectReturnsStdClassForObjectReturnType()
         $this->assertInstanceOf('stdClass', $result);
     }
 
-    public function testMakeObjectUsesOverrides()
+    public function testMakeObjectUsesOverrides(): void
     {
         $overrides = ['name' => 'The Admiral'];
 
@@ -338,7 +338,7 @@ public function testMakeObjectUsesOverrides()
         $this->assertSame($overrides['name'], $result->name);
     }
 
-    public function testMakeObjectReturnsValidData()
+    public function testMakeObjectReturnsValidData(): void
     {
         $fabricator = new Fabricator(UserModel::class, $this->formatters);
 
@@ -347,7 +347,7 @@ public function testMakeObjectReturnsValidData()
         $this->assertSame($result->email, filter_var($result->email, FILTER_VALIDATE_EMAIL));
     }
 
-    public function testMakeObjectUsesFakeMethod()
+    public function testMakeObjectUsesFakeMethod(): void
     {
         $fabricator = new Fabricator(FabricatorModel::class);
 
@@ -356,7 +356,7 @@ public function testMakeObjectUsesFakeMethod()
         $this->assertSame($result->name, filter_var($result->name, FILTER_VALIDATE_IP));
     }
 
-    public function testMakeReturnsSingleton()
+    public function testMakeReturnsSingleton(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -365,7 +365,7 @@ public function testMakeReturnsSingleton()
         $this->assertInstanceOf('stdClass', $result);
     }
 
-    public function testMakeReturnsExpectedCount()
+    public function testMakeReturnsExpectedCount(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -376,7 +376,7 @@ public function testMakeReturnsExpectedCount()
         $this->assertCount($count, $result);
     }
 
-    public function testCreateMockReturnsSingleton()
+    public function testCreateMockReturnsSingleton(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -385,7 +385,7 @@ public function testCreateMockReturnsSingleton()
         $this->assertInstanceOf('stdClass', $result);
     }
 
-    public function testCreateMockReturnsExpectedCount()
+    public function testCreateMockReturnsExpectedCount(): void
     {
         $fabricator = new Fabricator(UserModel::class);
 
@@ -396,7 +396,7 @@ public function testCreateMockReturnsExpectedCount()
         $this->assertCount($count, $result);
     }
 
-    public function testCreateMockSetsDatabaseFields()
+    public function testCreateMockSetsDatabaseFields(): void
     {
         $fabricator = new Fabricator(FabricatorModel::class);
 
@@ -410,14 +410,14 @@ public function testCreateMockSetsDatabaseFields()
         $this->assertNull($result->deleted_at);
     }
 
-    public function testSetCountReturnsCount()
+    public function testSetCountReturnsCount(): void
     {
         $result = Fabricator::setCount('goblins', 42);
 
         $this->assertSame(42, $result);
     }
 
-    public function testSetCountSetsValue()
+    public function testSetCountSetsValue(): void
     {
         Fabricator::setCount('trolls', 3);
         $result = Fabricator::getCount('trolls');
@@ -425,14 +425,14 @@ public function testSetCountSetsValue()
         $this->assertSame(3, $result);
     }
 
-    public function testGetCountNewTableReturnsZero()
+    public function testGetCountNewTableReturnsZero(): void
     {
         $result = Fabricator::getCount('gremlins');
 
         $this->assertSame(0, $result);
     }
 
-    public function testUpCountIncrementsValue()
+    public function testUpCountIncrementsValue(): void
     {
         Fabricator::setCount('orcs', 12);
         Fabricator::upCount('orcs');
@@ -440,7 +440,7 @@ public function testUpCountIncrementsValue()
         $this->assertSame(13, Fabricator::getCount('orcs'));
     }
 
-    public function testUpCountReturnsValue()
+    public function testUpCountReturnsValue(): void
     {
         Fabricator::setCount('hobgoblins', 12);
         $result = Fabricator::upCount('hobgoblins');
@@ -448,14 +448,14 @@ public function testUpCountReturnsValue()
         $this->assertSame(13, $result);
     }
 
-    public function testUpCountNewTableReturnsOne()
+    public function testUpCountNewTableReturnsOne(): void
     {
         $result = Fabricator::upCount('ogres');
 
         $this->assertSame(1, $result);
     }
 
-    public function testDownCountDecrementsValue()
+    public function testDownCountDecrementsValue(): void
     {
         Fabricator::setCount('orcs', 12);
         Fabricator::downCount('orcs');
@@ -463,7 +463,7 @@ public function testDownCountDecrementsValue()
         $this->assertSame(11, Fabricator::getCount('orcs'));
     }
 
-    public function testDownCountReturnsValue()
+    public function testDownCountReturnsValue(): void
     {
         Fabricator::setCount('hobgoblins', 12);
         $result = Fabricator::downCount('hobgoblins');
@@ -471,14 +471,14 @@ public function testDownCountReturnsValue()
         $this->assertSame(11, $result);
     }
 
-    public function testDownCountNewTableReturnsNegativeOne()
+    public function testDownCountNewTableReturnsNegativeOne(): void
     {
         $result = Fabricator::downCount('ogres');
 
         $this->assertSame(-1, $result);
     }
 
-    public function testResetClearsValue()
+    public function testResetClearsValue(): void
     {
         Fabricator::setCount('giants', 1000);
         Fabricator::resetCounts();
diff --git a/tests/system/Test/FeatureTestAutoRoutingImprovedTest.php b/tests/system/Test/FeatureTestAutoRoutingImprovedTest.php
index 19481a2860d3..a421408e9854 100644
--- a/tests/system/Test/FeatureTestAutoRoutingImprovedTest.php
+++ b/tests/system/Test/FeatureTestAutoRoutingImprovedTest.php
@@ -59,21 +59,21 @@ private static function initializeRouter(): void
         Services::injectMock('router', $router);
     }
 
-    public function testCallGet()
+    public function testCallGet(): void
     {
         $response = $this->get('newautorouting');
 
         $response->assertSee('Hello');
     }
 
-    public function testCallPost()
+    public function testCallPost(): void
     {
         $response = $this->post('newautorouting/save/1/a/b');
 
         $response->assertSee('Saved');
     }
 
-    public function testCallParamsCount()
+    public function testCallParamsCount(): void
     {
         $response = $this->post('newautorouting/save/1/a/b');
         $response->assertSee('Saved');
diff --git a/tests/system/Test/FeatureTestTraitTest.php b/tests/system/Test/FeatureTestTraitTest.php
index e26776d1fb29..dc6fa35a5975 100644
--- a/tests/system/Test/FeatureTestTraitTest.php
+++ b/tests/system/Test/FeatureTestTraitTest.php
@@ -41,7 +41,7 @@ protected function tearDown(): void
         $this->resetServices();
     }
 
-    public function testCallGet()
+    public function testCallGet(): void
     {
         $this->withRoutes([
             [
@@ -56,7 +56,7 @@ public function testCallGet()
         $response->assertDontSee('Again');
     }
 
-    public function testCallSimpleGet()
+    public function testCallSimpleGet(): void
     {
         $this->withRoutes([
             [
@@ -74,7 +74,7 @@ public function testCallSimpleGet()
         $this->assertSame(200, $response->response()->getStatusCode());
     }
 
-    public function testCallPost()
+    public function testCallPost(): void
     {
         $this->withRoutes([
             [
@@ -88,7 +88,7 @@ public function testCallPost()
         $response->assertSee('Hello Mars');
     }
 
-    public function testCallPostWithBody()
+    public function testCallPostWithBody(): void
     {
         $this->withRoutes([
             [
@@ -102,7 +102,7 @@ public function testCallPostWithBody()
         $response->assertSee('Hello Mars!');
     }
 
-    public function testCallValidationTwice()
+    public function testCallValidationTwice(): void
     {
         $this->withRoutes([
             [
@@ -132,7 +132,7 @@ static function () {
         $response->assertSee('Okay');
     }
 
-    public function testCallPut()
+    public function testCallPut(): void
     {
         $this->withRoutes([
             [
@@ -146,7 +146,7 @@ public function testCallPut()
         $response->assertSee('Hello Pluto');
     }
 
-    public function testCallPatch()
+    public function testCallPatch(): void
     {
         $this->withRoutes([
             [
@@ -160,7 +160,7 @@ public function testCallPatch()
         $response->assertSee('Hello Jupiter');
     }
 
-    public function testCallOptions()
+    public function testCallOptions(): void
     {
         $this->withRoutes([
             [
@@ -174,7 +174,7 @@ public function testCallOptions()
         $response->assertSee('Hello George');
     }
 
-    public function testCallDelete()
+    public function testCallDelete(): void
     {
         $this->withRoutes([
             [
@@ -188,7 +188,7 @@ public function testCallDelete()
         $response->assertSee('Hello Wonka');
     }
 
-    public function testSession()
+    public function testSession(): void
     {
         $response = $this->withRoutes([
             [
@@ -205,7 +205,7 @@ public function testSession()
         $response->assertSessionMissing('popcorn');
     }
 
-    public function testWithSessionNull()
+    public function testWithSessionNull(): void
     {
         $_SESSION = [
             'fruit'    => 'apple',
@@ -224,7 +224,7 @@ public function testWithSessionNull()
         $response->assertSessionMissing('popcorn');
     }
 
-    public function testReturns()
+    public function testReturns(): void
     {
         $this->withRoutes([
             [
@@ -237,7 +237,7 @@ public function testReturns()
         $response->assertSee('Hi');
     }
 
-    public function testIgnores()
+    public function testIgnores(): void
     {
         $this->withRoutes([
             [
@@ -250,7 +250,7 @@ public function testIgnores()
         $response->assertEmpty($response->response()->getBody());
     }
 
-    public function testEchoesWithParams()
+    public function testEchoesWithParams(): void
     {
         $this->withRoutes([
             [
@@ -264,7 +264,7 @@ public function testEchoesWithParams()
         $response->assertSee('Hello-o-o bar');
     }
 
-    public function testEchoesWithQuery()
+    public function testEchoesWithQuery(): void
     {
         $this->withRoutes([
             [
@@ -278,7 +278,7 @@ public function testEchoesWithQuery()
         $response->assertSee('Hello-o-o bar');
     }
 
-    public function testCallZeroAsPathGot404()
+    public function testCallZeroAsPathGot404(): void
     {
         $this->expectException(PageNotFoundException::class);
         $this->get('0');
@@ -322,7 +322,7 @@ public function provideRoutesData(): iterable
      * @param mixed $to
      * @param mixed $httpGet
      */
-    public function testOpenCliRoutesFromHttpGot404($from, $to, $httpGet)
+    public function testOpenCliRoutesFromHttpGot404($from, $to, $httpGet): void
     {
         $this->expectException(PageNotFoundException::class);
         $this->expectExceptionMessage('Cannot access CLI Route: ');
@@ -344,7 +344,7 @@ public function testOpenCliRoutesFromHttpGot404($from, $to, $httpGet)
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3072
      */
-    public function testIsOkWithRedirects()
+    public function testIsOkWithRedirects(): void
     {
         $this->withRoutes([
             [
@@ -358,7 +358,7 @@ public function testIsOkWithRedirects()
         $this->assertTrue($response->isOK());
     }
 
-    public function testCallGetWithParams()
+    public function testCallGetWithParams(): void
     {
         $this->withRoutes([
             [
@@ -385,7 +385,7 @@ public function testCallGetWithParams()
         );
     }
 
-    public function testCallGetWithParamsAndREQUEST()
+    public function testCallGetWithParamsAndREQUEST(): void
     {
         $this->withRoutes([
             [
@@ -412,7 +412,7 @@ public function testCallGetWithParamsAndREQUEST()
         );
     }
 
-    public function testCallPostWithParams()
+    public function testCallPostWithParams(): void
     {
         $this->withRoutes([
             [
@@ -439,7 +439,7 @@ public function testCallPostWithParams()
         );
     }
 
-    public function testCallPostWithParamsAndREQUEST()
+    public function testCallPostWithParamsAndREQUEST(): void
     {
         $this->withRoutes([
             [
@@ -466,7 +466,7 @@ public function testCallPostWithParamsAndREQUEST()
         );
     }
 
-    public function testCallPutWithJsonRequest()
+    public function testCallPutWithJsonRequest(): void
     {
         $this->withRoutes([
             [
@@ -490,7 +490,7 @@ public function testCallPutWithJsonRequest()
         $response->assertJSONExact($data);
     }
 
-    public function testCallPutWithJsonRequestAndREQUEST()
+    public function testCallPutWithJsonRequestAndREQUEST(): void
     {
         $this->withRoutes([
             [
@@ -514,7 +514,7 @@ public function testCallPutWithJsonRequestAndREQUEST()
         $this->assertStringContainsString('[]', $response->getBody());
     }
 
-    public function testCallWithJsonRequest()
+    public function testCallWithJsonRequest(): void
     {
         $this->withRoutes([
             [
@@ -538,7 +538,7 @@ public function testCallWithJsonRequest()
         $response->assertJSONExact($data);
     }
 
-    public function testSetupRequestBodyWithParams()
+    public function testSetupRequestBodyWithParams(): void
     {
         $request = $this->setupRequest('post', 'home');
 
@@ -548,7 +548,7 @@ public function testSetupRequestBodyWithParams()
         $this->assertSame('application/json', $request->header('Content-Type')->getValue());
     }
 
-    public function testSetupJSONRequestBodyWithBody()
+    public function testSetupJSONRequestBodyWithBody(): void
     {
         $request = $this->setupRequest('post', 'home');
         $request = $this->withBodyFormat('json')
@@ -565,7 +565,7 @@ public function testSetupJSONRequestBodyWithBody()
         );
     }
 
-    public function testSetupRequestBodyWithXml()
+    public function testSetupRequestBodyWithXml(): void
     {
         $request = $this->setupRequest('post', 'home');
 
@@ -587,7 +587,7 @@ public function testSetupRequestBodyWithXml()
         $this->assertSame('application/xml', $request->header('Content-Type')->getValue());
     }
 
-    public function testSetupRequestBodyWithBody()
+    public function testSetupRequestBodyWithBody(): void
     {
         $request = $this->setupRequest('post', 'home');
 
diff --git a/tests/system/Test/FilterTestTraitTest.php b/tests/system/Test/FilterTestTraitTest.php
index b50e2d18affe..32ebef106457 100644
--- a/tests/system/Test/FilterTestTraitTest.php
+++ b/tests/system/Test/FilterTestTraitTest.php
@@ -41,13 +41,13 @@ protected function setUp(): void
         $this->filtersConfig->globals['before']            = ['test-customfilter'];
     }
 
-    public function testDidRunTraitSetUp()
+    public function testDidRunTraitSetUp(): void
     {
         $this->assertTrue($this->doneFilterSetUp);
         $this->assertInstanceOf(RequestInterface::class, $this->request);
     }
 
-    public function testGetCallerReturnsClosure()
+    public function testGetCallerReturnsClosure(): void
     {
         $caller = $this->getFilterCaller('test-customfilter', 'before');
 
@@ -55,7 +55,7 @@ public function testGetCallerReturnsClosure()
         $this->assertInstanceOf('Closure', $caller);
     }
 
-    public function testGetCallerInvalidPosition()
+    public function testGetCallerInvalidPosition(): void
     {
         $this->expectException('InvalidArgumentException');
         $this->expectExceptionMessage('Invalid filter position passed: banana');
@@ -63,7 +63,7 @@ public function testGetCallerInvalidPosition()
         $this->getFilterCaller('test-customfilter', 'banana');
     }
 
-    public function testCallerUsesClonedInstance()
+    public function testCallerUsesClonedInstance(): void
     {
         $caller = $this->getFilterCaller('test-customfilter', 'before');
         $result = $caller();
@@ -73,31 +73,31 @@ public function testCallerUsesClonedInstance()
         $this->resetServices();
     }
 
-    public function testGetFiltersForRoute()
+    public function testGetFiltersForRoute(): void
     {
         $result = $this->getFiltersForRoute('/', 'before');
 
         $this->assertSame(['test-customfilter'], $result);
     }
 
-    public function testAssertFilter()
+    public function testAssertFilter(): void
     {
         $this->assertFilter('/', 'before', 'test-customfilter');
         $this->assertFilter('/', 'after', 'toolbar');
     }
 
-    public function testAssertNotFilter()
+    public function testAssertNotFilter(): void
     {
         $this->assertNotFilter('/', 'before', 'foobar');
         $this->assertNotFilter('/', 'after', 'test-customfilter');
     }
 
-    public function testAssertHasFilters()
+    public function testAssertHasFilters(): void
     {
         $this->assertHasFilters('/', 'before');
     }
 
-    public function testAssertNotHasFilters()
+    public function testAssertNotHasFilters(): void
     {
         $this->filtersConfig->globals['before'] = [];
 
diff --git a/tests/system/Test/ReflectionHelperTest.php b/tests/system/Test/ReflectionHelperTest.php
index 8a8978f84eb5..414053b26dc1 100644
--- a/tests/system/Test/ReflectionHelperTest.php
+++ b/tests/system/Test/ReflectionHelperTest.php
@@ -18,21 +18,21 @@
  */
 final class ReflectionHelperTest extends CIUnitTestCase
 {
-    public function testGetPrivatePropertyWithObject()
+    public function testGetPrivatePropertyWithObject(): void
     {
         $obj    = new __TestForReflectionHelper();
         $actual = $this->getPrivateProperty($obj, 'private');
         $this->assertSame('secret', $actual);
     }
 
-    public function testGetPrivatePropertyWithObjectStaticCall()
+    public function testGetPrivatePropertyWithObjectStaticCall(): void
     {
         $obj    = new __TestForReflectionHelper();
         $actual = CIUnitTestCase::getPrivateProperty($obj, 'private');
         $this->assertSame('secret', $actual);
     }
 
-    public function testGetPrivatePropertyWithStatic()
+    public function testGetPrivatePropertyWithStatic(): void
     {
         $actual = $this->getPrivateProperty(
             __TestForReflectionHelper::class,
@@ -41,7 +41,7 @@ public function testGetPrivatePropertyWithStatic()
         $this->assertSame('xyz', $actual);
     }
 
-    public function testSetPrivatePropertyWithObject()
+    public function testSetPrivatePropertyWithObject(): void
     {
         $obj = new __TestForReflectionHelper();
         $this->setPrivateProperty(
@@ -52,7 +52,7 @@ public function testSetPrivatePropertyWithObject()
         $this->assertSame('open', $obj->getPrivate());
     }
 
-    public function testSetPrivatePropertyWithStatic()
+    public function testSetPrivatePropertyWithStatic(): void
     {
         $this->setPrivateProperty(
             __TestForReflectionHelper::class,
@@ -65,7 +65,7 @@ public function testSetPrivatePropertyWithStatic()
         );
     }
 
-    public function testGetPrivateMethodInvokerWithObject()
+    public function testGetPrivateMethodInvokerWithObject(): void
     {
         $obj    = new __TestForReflectionHelper();
         $method = $this->getPrivateMethodInvoker(
@@ -78,7 +78,7 @@ public function testGetPrivateMethodInvokerWithObject()
         );
     }
 
-    public function testGetPrivateMethodInvokerWithStatic()
+    public function testGetPrivateMethodInvokerWithStatic(): void
     {
         $method = $this->getPrivateMethodInvoker(
             __TestForReflectionHelper::class,
diff --git a/tests/system/Test/TestCaseEmissionsTest.php b/tests/system/Test/TestCaseEmissionsTest.php
index 981fa66fec5f..a6ea7f891e54 100644
--- a/tests/system/Test/TestCaseEmissionsTest.php
+++ b/tests/system/Test/TestCaseEmissionsTest.php
@@ -44,7 +44,7 @@ final class TestCaseEmissionsTest extends CIUnitTestCase
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeadersEmitted()
+    public function testHeadersEmitted(): void
     {
         $response = new Response(new App());
         $response->pretend(false);
@@ -72,7 +72,7 @@ public function testHeadersEmitted()
      * @runInSeparateProcess
      * @preserveGlobalState disabled
      */
-    public function testHeadersNotEmitted()
+    public function testHeadersNotEmitted(): void
     {
         $response = new Response(new App());
         $response->pretend(false);
diff --git a/tests/system/Test/TestCaseTest.php b/tests/system/Test/TestCaseTest.php
index dc2feda00210..e5e1ed8cb3f6 100644
--- a/tests/system/Test/TestCaseTest.php
+++ b/tests/system/Test/TestCaseTest.php
@@ -33,28 +33,28 @@ protected function setUp(): void
         CLI::print();
     }
 
-    public function testGetPrivatePropertyWithObject()
+    public function testGetPrivatePropertyWithObject(): void
     {
         $obj    = new __TestForReflectionHelper();
         $actual = $this->getPrivateProperty($obj, 'private');
         $this->assertSame('secret', $actual);
     }
 
-    public function testLogging()
+    public function testLogging(): void
     {
         log_message('error', 'Some variable did not contain a value.');
         $this->assertLogged('error', 'Some variable did not contain a value.');
     }
 
-    public function testAssertLogContains()
+    public function testAssertLogContains(): void
     {
         log_message('error', 'Some variable did not contain a value.');
         $this->assertLogContains('error', 'variable did not');
     }
 
-    public function testEventTriggering()
+    public function testEventTriggering(): void
     {
-        Events::on('foo', static function ($arg) use (&$result) {
+        Events::on('foo', static function ($arg) use (&$result): void {
             $result = $arg;
         });
 
@@ -63,7 +63,7 @@ public function testEventTriggering()
         $this->assertEventTriggered('foo');
     }
 
-    public function testStreamFilter()
+    public function testStreamFilter(): void
     {
         CLI::write('first.');
         $expected = PHP_EOL . 'first.' . PHP_EOL;
@@ -79,7 +79,7 @@ public function testStreamFilter()
      * TestCaseEmissionsTest is intended to circumvent PHPunit,
      * and allow us to test our own header emissions.
      */
-    public function testPHPUnitHeadersEmitted()
+    public function testPHPUnitHeadersEmitted(): void
     {
         $response = new Response(new App());
         $response->pretend(true);
@@ -95,21 +95,21 @@ public function testPHPUnitHeadersEmitted()
         $this->assertHeaderNotEmitted('Set-Cookie: foo=bar;');
     }
 
-    public function testCloseEnough()
+    public function testCloseEnough(): void
     {
         $this->assertCloseEnough(1, 1);
         $this->assertCloseEnough(1, 0);
         $this->assertCloseEnough(1, 2);
     }
 
-    public function testCloseEnoughString()
+    public function testCloseEnoughString(): void
     {
         $this->assertCloseEnoughString(strtotime('10:00:00'), strtotime('09:59:59'));
         $this->assertCloseEnoughString(strtotime('10:00:00'), strtotime('10:00:00'));
         $this->assertCloseEnoughString(strtotime('10:00:00'), strtotime('10:00:01'));
     }
 
-    public function testCloseEnoughStringBadLength()
+    public function testCloseEnoughStringBadLength(): void
     {
         $result = $this->assertCloseEnoughString('apples & oranges', 'apples');
         $this->assertFalse($result, 'Different string lengths should have returned false');
diff --git a/tests/system/Test/TestResponseTest.php b/tests/system/Test/TestResponseTest.php
index 63b7d9c7aa94..48baf0cf4a66 100644
--- a/tests/system/Test/TestResponseTest.php
+++ b/tests/system/Test/TestResponseTest.php
@@ -35,7 +35,7 @@ protected function setUp(): void
     /**
      * @dataProvider statusCodeProvider
      */
-    public function testIsOK(int $code, bool $isOk)
+    public function testIsOK(int $code, bool $isOk): void
     {
         $this->getTestResponse('Hello World');
         $this->response->setStatusCode($code);
@@ -84,7 +84,7 @@ public function statusCodeProvider(): iterable
         ];
     }
 
-    public function testIsOKEmpty()
+    public function testIsOKEmpty(): void
     {
         $this->getTestResponse('Hi there');
         $this->response->setStatusCode(200);
@@ -93,7 +93,7 @@ public function testIsOKEmpty()
         $this->assertFalse($this->testResponse->isOK());
     }
 
-    public function testAssertSee()
+    public function testAssertSee(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
@@ -101,7 +101,7 @@ public function testAssertSee()
         $this->testResponse->assertSee('World', 'h1');
     }
 
-    public function testAssertDontSee()
+    public function testAssertDontSee(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
@@ -109,7 +109,7 @@ public function testAssertDontSee()
         $this->testResponse->assertDontSee('World', 'h2');
     }
 
-    public function testAssertSeeElement()
+    public function testAssertSeeElement(): void
     {
         $this->getTestResponse('<h1 class="header">Hello <span>World</span></h1>');
 
@@ -118,7 +118,7 @@ public function testAssertSeeElement()
         $this->testResponse->assertSeeElement('h1.header');
     }
 
-    public function testAssertDontSeeElement()
+    public function testAssertDontSeeElement(): void
     {
         $this->getTestResponse('<h1 class="header">Hello <span>World</span></h1>');
 
@@ -127,7 +127,7 @@ public function testAssertDontSeeElement()
         $this->testResponse->assertDontSeeElement('h1.para');
     }
 
-    public function testAssertSeeLink()
+    public function testAssertSeeLink(): void
     {
         $this->getTestResponse('<h1 class="header"><a href="http://example.com/hello">Hello</a> <span>World</span></h1>');
 
@@ -135,14 +135,14 @@ public function testAssertSeeLink()
         $this->testResponse->assertSeeLink('Hello');
     }
 
-    public function testAssertSeeInField()
+    public function testAssertSeeInField(): void
     {
         $this->getTestResponse('<html><body><input type="text" name="user[name]" value="Foobar"></body></html>');
 
         $this->testResponse->assertSeeInField('user[name]', 'Foobar');
     }
 
-    public function testAssertRedirectFail()
+    public function testAssertRedirectFail(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
@@ -151,7 +151,7 @@ public function testAssertRedirectFail()
         $this->testResponse->assertNotRedirect();
     }
 
-    public function testAssertRedirectSuccess()
+    public function testAssertRedirectSuccess(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->testResponse->setResponse(new RedirectResponse(new App()));
@@ -161,7 +161,7 @@ public function testAssertRedirectSuccess()
         $this->testResponse->assertRedirect();
     }
 
-    public function testAssertRedirectSuccessWithoutRedirectResponse()
+    public function testAssertRedirectSuccessWithoutRedirectResponse(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->response->redirect('foo/bar');
@@ -172,7 +172,7 @@ public function testAssertRedirectSuccessWithoutRedirectResponse()
         $this->assertSame('foo/bar', $this->testResponse->getRedirectUrl());
     }
 
-    public function testGetRedirectUrlReturnsUrl()
+    public function testGetRedirectUrlReturnsUrl(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->testResponse->setResponse(new RedirectResponse(new App()));
@@ -181,14 +181,14 @@ public function testGetRedirectUrlReturnsUrl()
         $this->assertSame('foo/bar', $this->testResponse->getRedirectUrl());
     }
 
-    public function testGetRedirectUrlReturnsNull()
+    public function testGetRedirectUrlReturnsNull(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
         $this->assertNull($this->testResponse->getRedirectUrl());
     }
 
-    public function testRedirectToSuccess()
+    public function testRedirectToSuccess(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->testResponse->setResponse(new RedirectResponse(new App()));
@@ -197,7 +197,7 @@ public function testRedirectToSuccess()
         $this->testResponse->assertRedirectTo('foo/bar');
     }
 
-    public function testRedirectToSuccessFullURL()
+    public function testRedirectToSuccessFullURL(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->testResponse->setResponse(new RedirectResponse(new App()));
@@ -206,7 +206,7 @@ public function testRedirectToSuccessFullURL()
         $this->testResponse->assertRedirectTo('http://foo.com/bar');
     }
 
-    public function testRedirectToSuccessMixedURL()
+    public function testRedirectToSuccessMixedURL(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->testResponse->setResponse(new RedirectResponse(new App()));
@@ -215,7 +215,7 @@ public function testRedirectToSuccessMixedURL()
         $this->testResponse->assertRedirectTo('http://example.com/index.php/bar');
     }
 
-    public function testAssertStatus()
+    public function testAssertStatus(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>', ['statusCode' => 201]);
 
@@ -225,7 +225,7 @@ public function testAssertStatus()
     /**
      * @dataProvider statusCodeProvider
      */
-    public function testAssertIsOK(int $code, bool $isOk)
+    public function testAssertIsOK(int $code, bool $isOk): void
     {
         $this->getTestResponse('<h1>Hello World</h1>', ['statusCode' => $code]);
 
@@ -236,7 +236,7 @@ public function testAssertIsOK(int $code, bool $isOk)
         }
     }
 
-    public function testAssertSessionHas()
+    public function testAssertSessionHas(): void
     {
         $_SESSION['foo'] = 'bar';
         $this->getTestResponse('<h1>Hello World</h1>');
@@ -245,7 +245,7 @@ public function testAssertSessionHas()
         $this->testResponse->assertSessionHas('foo', 'bar');
     }
 
-    public function testAssertSessionMissing()
+    public function testAssertSessionMissing(): void
     {
         $_SESSION = [];
         $this->getTestResponse('<h1>Hello World</h1>');
@@ -253,7 +253,7 @@ public function testAssertSessionMissing()
         $this->testResponse->assertSessionMissing('foo');
     }
 
-    public function testAssertHeader()
+    public function testAssertHeader(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>', [], ['foo' => 'bar']);
 
@@ -261,7 +261,7 @@ public function testAssertHeader()
         $this->testResponse->assertHeader('foo', 'bar');
     }
 
-    public function testAssertHeaderMissing()
+    public function testAssertHeaderMissing(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>', [], ['foo' => 'bar']);
 
@@ -269,7 +269,7 @@ public function testAssertHeaderMissing()
         $this->testResponse->assertHeaderMissing('banana');
     }
 
-    public function testAssertCookie()
+    public function testAssertCookie(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
@@ -279,7 +279,7 @@ public function testAssertCookie()
         $this->testResponse->assertCookie('foo', 'bar');
     }
 
-    public function testAssertCookieMissing()
+    public function testAssertCookieMissing(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
@@ -288,7 +288,7 @@ public function testAssertCookieMissing()
         $this->testResponse->assertCookieMissing('bar');
     }
 
-    public function testAssertCookieExpired()
+    public function testAssertCookieExpired(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
 
@@ -297,7 +297,7 @@ public function testAssertCookieExpired()
         $this->testResponse->assertCookieExpired('foo');
     }
 
-    public function testGetJSON()
+    public function testGetJSON(): void
     {
         $data = ['foo' => 'bar'];
         $this->getTestResponse('');
@@ -307,7 +307,7 @@ public function testGetJSON()
         $this->assertSame($formatter->format($data), $this->testResponse->getJSON());
     }
 
-    public function testGetJSONEmptyJSON()
+    public function testGetJSONEmptyJSON(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->response->setJSON('', true);
@@ -316,7 +316,7 @@ public function testGetJSONEmptyJSON()
         $this->assertSame('""', $this->testResponse->getJSON());
     }
 
-    public function testGetJSONFalseJSON()
+    public function testGetJSONFalseJSON(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->response->setJSON(false, true);
@@ -325,7 +325,7 @@ public function testGetJSONFalseJSON()
         $this->assertSame('false', $this->testResponse->getJSON());
     }
 
-    public function testGetJSONTrueJSON()
+    public function testGetJSONTrueJSON(): void
     {
         $this->getTestResponse('<h1>Hello World</h1>');
         $this->response->setJSON(true, true);
@@ -334,7 +334,7 @@ public function testGetJSONTrueJSON()
         $this->assertSame('true', $this->testResponse->getJSON());
     }
 
-    public function testGetJSONInvalidJSON()
+    public function testGetJSONInvalidJSON(): void
     {
         $tmp = ' test " case ';
         $this->getTestResponse('<h1>Hello World</h1>');
@@ -344,7 +344,7 @@ public function testGetJSONInvalidJSON()
         $this->assertNotSame($this->testResponse->getJSON(), $this->response->getBody());
     }
 
-    public function testGetXML()
+    public function testGetXML(): void
     {
         $data = ['foo' => 'bar'];
         $this->getTestResponse('');
@@ -354,7 +354,7 @@ public function testGetXML()
         $this->assertSame($formatter->format($data), $this->testResponse->getXML());
     }
 
-    public function testAssertJSONFragment()
+    public function testAssertJSONFragment(): void
     {
         $data = [
             'config' => [
@@ -369,7 +369,7 @@ public function testAssertJSONFragment()
         $this->testResponse->assertJSONFragment(['config' => ['key-a']], true);
     }
 
-    public function testAssertJSONFragmentFollowingAssertArraySubset()
+    public function testAssertJSONFragmentFollowingAssertArraySubset(): void
     {
         $data = [
             'config' => '124',
@@ -381,7 +381,7 @@ public function testAssertJSONFragmentFollowingAssertArraySubset()
         $this->testResponse->assertJSONFragment(['config' => '124'], true);
     }
 
-    public function testAssertJSONFragmentFailsGracefullyWhenNotGivenJson()
+    public function testAssertJSONFragmentFailsGracefullyWhenNotGivenJson(): void
     {
         $this->getTestResponse('<h1>Hello World!</h1>');
 
@@ -391,7 +391,7 @@ public function testAssertJSONFragmentFailsGracefullyWhenNotGivenJson()
         $this->testResponse->assertJSONFragment(['foo' => 'bar']);
     }
 
-    public function testAssertJsonExactArray()
+    public function testAssertJsonExactArray(): void
     {
         $data = [
             'config' => [
@@ -405,7 +405,7 @@ public function testAssertJsonExactArray()
         $this->testResponse->assertJSONExact($data);
     }
 
-    public function testAssertJsonExactObject()
+    public function testAssertJsonExactObject(): void
     {
         $data = (object) [
             'config' => [
@@ -419,7 +419,7 @@ public function testAssertJsonExactObject()
         $this->testResponse->assertJSONExact($data);
     }
 
-    public function testAssertJsonExactString()
+    public function testAssertJsonExactString(): void
     {
         $data = [
             'config' => [
@@ -434,7 +434,7 @@ public function testAssertJsonExactString()
         $this->testResponse->assertJSONExact($formatter->format($data));
     }
 
-    protected function getTestResponse(?string $body = null, array $responseOptions = [], array $headers = [])
+    protected function getTestResponse(?string $body = null, array $responseOptions = [], array $headers = []): void
     {
         $this->response = new Response(new App());
         $this->response->setBody($body);
diff --git a/tests/system/Throttle/ThrottleTest.php b/tests/system/Throttle/ThrottleTest.php
index 3bdd2e661224..83a44878cf76 100644
--- a/tests/system/Throttle/ThrottleTest.php
+++ b/tests/system/Throttle/ThrottleTest.php
@@ -31,7 +31,7 @@ protected function setUp(): void
         $this->cache = new MockCache();
     }
 
-    public function testTokenTime()
+    public function testTokenTime(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -53,7 +53,7 @@ public function testTokenTime()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5458
      */
-    public function testTokenTimeCalculation()
+    public function testTokenTimeCalculation(): void
     {
         $time = 1_639_441_295;
 
@@ -86,7 +86,7 @@ public function testTokenTimeCalculation()
         $this->assertSame(97, $throttler->getTokenTime(), 'Wrong token time');
     }
 
-    public function testIPSavesBucket()
+    public function testIPSavesBucket(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -94,7 +94,7 @@ public function testIPSavesBucket()
         $this->assertSame(59, $this->cache->get('throttler_127.0.0.1'));
     }
 
-    public function testRemove()
+    public function testRemove(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -107,7 +107,7 @@ public function testRemove()
         $this->assertTrue($throttler->check('127.0.0.1', 1, MINUTE));
     }
 
-    public function testDecrementsValues()
+    public function testDecrementsValues(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -118,7 +118,7 @@ public function testDecrementsValues()
         $this->assertCloseEnough(57, $this->cache->get('throttler_127.0.0.1'));
     }
 
-    public function testReturnsFalseIfBucketEmpty()
+    public function testReturnsFalseIfBucketEmpty(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -127,7 +127,7 @@ public function testReturnsFalseIfBucketEmpty()
         $this->assertFalse($throttler->check('127.0.0.1', 1, MINUTE));
     }
 
-    public function testCosting()
+    public function testCosting(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -137,7 +137,7 @@ public function testCosting()
         $this->assertSame($rate - $cost, $this->cache->get('throttler_127.0.0.1'));
     }
 
-    public function testUnderload()
+    public function testUnderload(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -151,7 +151,7 @@ public function testUnderload()
         $this->assertSame($rate - 1, $this->cache->get('throttler_127.0.0.1'));
     }
 
-    public function testOverload()
+    public function testOverload(): void
     {
         $throttler = new Throttler($this->cache);
 
@@ -163,7 +163,7 @@ public function testOverload()
         $this->assertFalse($throttler->check('127.0.0.1', $rate, MINUTE, $cost));
     }
 
-    public function testFlooding()
+    public function testFlooding(): void
     {
         $time = 1_639_441_295;
 
diff --git a/tests/system/Typography/TypographyTest.php b/tests/system/Typography/TypographyTest.php
index b23bd420f951..e5d87fa5831c 100644
--- a/tests/system/Typography/TypographyTest.php
+++ b/tests/system/Typography/TypographyTest.php
@@ -28,12 +28,12 @@ protected function setUp(): void
         $this->typography = new Typography();
     }
 
-    public function testAutoTypographyEmptyString()
+    public function testAutoTypographyEmptyString(): void
     {
         $this->assertSame('', $this->typography->autoTypography(''));
     }
 
-    public function testAutoTypographyNormalString()
+    public function testAutoTypographyNormalString(): void
     {
         $strs = [
             'this sentence has no punctuations' => '<p>this sentence has no punctuations</p>',
@@ -45,7 +45,7 @@ public function testAutoTypographyNormalString()
         }
     }
 
-    public function testAutoTypographyMultipleSpaces()
+    public function testAutoTypographyMultipleSpaces(): void
     {
         $strs = [
             'this sentence has  a double spacing'              => '<p>this sentence has  a double spacing</p>',
@@ -57,7 +57,7 @@ public function testAutoTypographyMultipleSpaces()
         }
     }
 
-    public function testAutoTypographyLineBreaks()
+    public function testAutoTypographyLineBreaks(): void
     {
         $strs = [
             "\n"                                   => "\n\n<p>&nbsp;</p>",
@@ -77,7 +77,7 @@ public function testAutoTypographyLineBreaks()
         }
     }
 
-    public function testAutoTypographyReduceLineBreaks()
+    public function testAutoTypographyReduceLineBreaks(): void
     {
         $strs = [
             "\n"                                   => "\n\n",
@@ -97,7 +97,7 @@ public function testAutoTypographyReduceLineBreaks()
         }
     }
 
-    public function testAutoTypographyHTMLComment()
+    public function testAutoTypographyHTMLComment(): void
     {
         $strs = [
             '<!-- this is an HTML comment -->'                       => '<!-- this is an HTML comment -->',
@@ -110,7 +110,7 @@ public function testAutoTypographyHTMLComment()
         }
     }
 
-    public function testAutoTypographyHTMLTags()
+    public function testAutoTypographyHTMLTags(): void
     {
         $strs = [
             '<b>Hello World !!</b>, How are you?'               => '<p><b>Hello World !!</b>, How are you?</p>',
@@ -125,7 +125,7 @@ public function testAutoTypographyHTMLTags()
         }
     }
 
-    public function testAutoTypographySpecialCharacters()
+    public function testAutoTypographySpecialCharacters(): void
     {
         $strs = [
             '\'Text in single quotes\''      => '<p>&#8216;Text in single quotes&#8217;</p>',
@@ -138,7 +138,7 @@ public function testAutoTypographySpecialCharacters()
         }
     }
 
-    public function testNewlinesToHTMLLineBreaksExceptWithinPRE()
+    public function testNewlinesToHTMLLineBreaksExceptWithinPRE(): void
     {
         $strs = [
             "Line One\nLine Two"            => "Line One<br>\nLine Two",
diff --git a/tests/system/Validation/FormatRulesTest.php b/tests/system/Validation/FormatRulesTest.php
index 7f1de6439345..c04ed0eb22e5 100644
--- a/tests/system/Validation/FormatRulesTest.php
+++ b/tests/system/Validation/FormatRulesTest.php
@@ -87,7 +87,7 @@ public function testRegexMatchFalse(): void
     /**
      * @dataProvider urlProvider
      */
-    public function testValidURL(?string $url, bool $isLoose, bool $isStrict)
+    public function testValidURL(?string $url, bool $isLoose, bool $isStrict): void
     {
         $data = [
             'foo' => $url,
@@ -103,7 +103,7 @@ public function testValidURL(?string $url, bool $isLoose, bool $isStrict)
     /**
      * @dataProvider urlProvider
      */
-    public function testValidURLStrict(?string $url, bool $isLoose, bool $isStrict)
+    public function testValidURLStrict(?string $url, bool $isLoose, bool $isStrict): void
     {
         $data = [
             'foo' => $url,
@@ -116,7 +116,7 @@ public function testValidURLStrict(?string $url, bool $isLoose, bool $isStrict)
         $this->assertSame($isStrict, $this->validation->run($data));
     }
 
-    public function testValidURLStrictWithSchema()
+    public function testValidURLStrictWithSchema(): void
     {
         $data = [
             'foo' => 'http://www.codeigniter.com',
diff --git a/tests/system/Validation/ValidationTest.php b/tests/system/Validation/ValidationTest.php
index 638dd56e26d2..ab09c9d8238a 100644
--- a/tests/system/Validation/ValidationTest.php
+++ b/tests/system/Validation/ValidationTest.php
@@ -93,7 +93,7 @@ public function testSetRulesStoresRules(): void
         $this->assertSame($expected, $this->validation->getRules());
     }
 
-    public function testSetRuleStoresRule()
+    public function testSetRuleStoresRule(): void
     {
         $this->validation->setRules([]);
         $this->validation->setRule('foo', null, 'bar|baz');
@@ -106,7 +106,7 @@ public function testSetRuleStoresRule()
         ], $this->validation->getRules());
     }
 
-    public function testSetRuleMultipleWithIndividual()
+    public function testSetRuleMultipleWithIndividual(): void
     {
         $this->validation->setRule('username', 'Username', 'required|min_length[3]');
         $this->validation->setRule('password', 'Password', ['required', 'min_length[8]', 'alpha_numeric_punct']);
@@ -127,7 +127,7 @@ public function testSetRuleMultipleWithIndividual()
         ], $this->validation->getRules());
     }
 
-    public function testSetRuleAddsRule()
+    public function testSetRuleAddsRule(): void
     {
         $this->validation->setRules([
             'bar' => [
@@ -149,7 +149,7 @@ public function testSetRuleAddsRule()
         ], $this->validation->getRules());
     }
 
-    public function testSetRuleOverwritesRule()
+    public function testSetRuleOverwritesRule(): void
     {
         $this->validation->setRules([
             'foo' => [
@@ -167,7 +167,7 @@ public function testSetRuleOverwritesRule()
         ], $this->validation->getRules());
     }
 
-    public function testSetRuleOverwritesRuleReverse()
+    public function testSetRuleOverwritesRuleReverse(): void
     {
         $this->validation->setRule('foo', null, 'foo|foz');
         $this->validation->setRules([
@@ -234,7 +234,7 @@ public function setRuleRulesFormatCaseProvider(): iterable
         ];
     }
 
-    public function testRunReturnsFalseWithNothingToDo()
+    public function testRunReturnsFalseWithNothingToDo(): void
     {
         $this->validation->setRules([]);
         $this->assertFalse($this->validation->run([]));
@@ -613,7 +613,7 @@ public function testRunWithCustomErrorsAndAsteriskField(): void
      * @param string|string[] $rules
      * @param string          $expected
      */
-    public function testRulesSetup($rules, $expected, array $errors = [])
+    public function testRulesSetup($rules, $expected, array $errors = []): void
     {
         $data = ['foo' => ''];
         $this->validation->setRules(['foo' => $rules], $errors);
@@ -958,7 +958,7 @@ public function testRulesForObjectField(): void
     /**
      * @dataProvider arrayFieldDataProvider
      */
-    public function testRulesForArrayField(array $body, array $rules, array $results)
+    public function testRulesForArrayField(array $body, array $rules, array $results): void
     {
         $config          = new App();
         $config->baseURL = 'http://example.com/';
@@ -1387,7 +1387,7 @@ public function provideStringRulesCases(): iterable
      *
      * @source https://github.com/codeigniter4/CodeIgniter4/pull/3910#issuecomment-784922913
      */
-    protected function placeholderReplacementResultDetermination(string $placeholder = 'id', ?array $data = null)
+    protected function placeholderReplacementResultDetermination(string $placeholder = 'id', ?array $data = null): void
     {
         if ($data === null) {
             $data = [$placeholder => '12'];
@@ -1411,7 +1411,7 @@ protected function placeholderReplacementResultDetermination(string $placeholder
     /**
      * @see ValidationTest::placeholderReplacementResultDetermination()
      */
-    public function testPlaceholderReplacementTestFails()
+    public function testPlaceholderReplacementTestFails(): void
     {
         // to test if placeholderReplacementResultDetermination() works we provoke and expect an exception
         $this->expectException(ExpectationFailedException::class);
@@ -1423,7 +1423,7 @@ public function testPlaceholderReplacementTestFails()
         $this->placeholderReplacementResultDetermination('id', []);
     }
 
-    public function testPlaceholderReplacementSetSingleRuleString()
+    public function testPlaceholderReplacementSetSingleRuleString(): void
     {
         $this->validation->setRule('id', null, 'required|is_natural_no_zero');
         $this->validation->setRule('foo', null, 'required|filter[{id}]');
@@ -1431,7 +1431,7 @@ public function testPlaceholderReplacementSetSingleRuleString()
         $this->placeholderReplacementResultDetermination();
     }
 
-    public function testPlaceholderReplacementSetSingleRuleArray()
+    public function testPlaceholderReplacementSetSingleRuleArray(): void
     {
         $this->validation->setRule('id', null, ['required', 'is_natural_no_zero']);
         $this->validation->setRule('foo', null, ['required', 'filter[{id}]']);
@@ -1439,7 +1439,7 @@ public function testPlaceholderReplacementSetSingleRuleArray()
         $this->placeholderReplacementResultDetermination();
     }
 
-    public function testPlaceholderReplacementSetMultipleRulesSimpleString()
+    public function testPlaceholderReplacementSetMultipleRulesSimpleString(): void
     {
         $this->validation->setRules([
             'id'  => 'required|is_natural_no_zero',
@@ -1449,7 +1449,7 @@ public function testPlaceholderReplacementSetMultipleRulesSimpleString()
         $this->placeholderReplacementResultDetermination();
     }
 
-    public function testPlaceholderReplacementSetMultipleRulesSimpleArray()
+    public function testPlaceholderReplacementSetMultipleRulesSimpleArray(): void
     {
         $this->validation->setRules([
             'id'  => ['required', 'is_natural_no_zero'],
@@ -1459,7 +1459,7 @@ public function testPlaceholderReplacementSetMultipleRulesSimpleArray()
         $this->placeholderReplacementResultDetermination();
     }
 
-    public function testPlaceholderReplacementSetMultipleRulesComplexString()
+    public function testPlaceholderReplacementSetMultipleRulesComplexString(): void
     {
         $this->validation->setRules([
             'id' => [
@@ -1473,7 +1473,7 @@ public function testPlaceholderReplacementSetMultipleRulesComplexString()
         $this->placeholderReplacementResultDetermination();
     }
 
-    public function testPlaceholderReplacementSetMultipleRulesComplexArray()
+    public function testPlaceholderReplacementSetMultipleRulesComplexArray(): void
     {
         $this->validation->setRules([
             'id' => [
@@ -1578,7 +1578,7 @@ public function testRuleWithLeadingAsterisk(): void
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5942
      */
-    public function testRequireWithoutWithWildCard()
+    public function testRequireWithoutWithWildCard(): void
     {
         $data = [
             'a' => [
diff --git a/tests/system/View/CellTest.php b/tests/system/View/CellTest.php
index 5c1863236ab1..094db319a747 100644
--- a/tests/system/View/CellTest.php
+++ b/tests/system/View/CellTest.php
@@ -34,17 +34,17 @@ protected function setUp(): void
         $this->cell  = new Cell($this->cache);
     }
 
-    public function testPrepareParamsReturnsEmptyArrayWithInvalidParam()
+    public function testPrepareParamsReturnsEmptyArrayWithInvalidParam(): void
     {
         $this->assertSame([], $this->cell->prepareParams(1.023));
     }
 
-    public function testPrepareParamsReturnsNullWithEmptyString()
+    public function testPrepareParamsReturnsNullWithEmptyString(): void
     {
         $this->assertSame([], $this->cell->prepareParams(''));
     }
 
-    public function testPrepareParamsReturnsSelfWhenArray()
+    public function testPrepareParamsReturnsSelfWhenArray(): void
     {
         $object = [
             'one'   => 'two',
@@ -54,12 +54,12 @@ public function testPrepareParamsReturnsSelfWhenArray()
         $this->assertSame($object, $this->cell->prepareParams($object));
     }
 
-    public function testPrepareParamsReturnsEmptyArrayWithEmptyArray()
+    public function testPrepareParamsReturnsEmptyArrayWithEmptyArray(): void
     {
         $this->assertSame([], $this->cell->prepareParams([]));
     }
 
-    public function testPrepareParamsReturnsArrayWithString()
+    public function testPrepareParamsReturnsArrayWithString(): void
     {
         $params   = 'one=two three=four';
         $expected = [
@@ -70,7 +70,7 @@ public function testPrepareParamsReturnsArrayWithString()
         $this->assertSame($expected, $this->cell->prepareParams($params));
     }
 
-    public function testPrepareParamsHandlesCommas()
+    public function testPrepareParamsHandlesCommas(): void
     {
         $params   = 'one=2, three=4.15';
         $expected = [
@@ -81,7 +81,7 @@ public function testPrepareParamsHandlesCommas()
         $this->assertSame($expected, $this->cell->prepareParams($params));
     }
 
-    public function testPrepareParamsWorksWithoutSpaces()
+    public function testPrepareParamsWorksWithoutSpaces(): void
     {
         $params   = 'one=two,three=four';
         $expected = [
@@ -92,7 +92,7 @@ public function testPrepareParamsWorksWithoutSpaces()
         $this->assertSame($expected, $this->cell->prepareParams($params));
     }
 
-    public function testPrepareParamsWorksWithOddEqualsSpaces()
+    public function testPrepareParamsWorksWithOddEqualsSpaces(): void
     {
         $params   = 'one= two,three =four, five = six';
         $expected = [
@@ -106,14 +106,14 @@ public function testPrepareParamsWorksWithOddEqualsSpaces()
 
     // Render
 
-    public function testDisplayRendersWithNamespacedClass()
+    public function testDisplayRendersWithNamespacedClass(): void
     {
         $expected = 'Hello';
 
         $this->assertSame($expected, $this->cell->render('\Tests\Support\View\SampleClass::hello'));
     }
 
-    public function testDisplayRendersTwoCellsWithSameShortName()
+    public function testDisplayRendersTwoCellsWithSameShortName(): void
     {
         $output = $this->cell->render('\Tests\Support\View\SampleClass::hello');
 
@@ -124,7 +124,7 @@ public function testDisplayRendersTwoCellsWithSameShortName()
         $this->assertSame('Good-bye!', $output);
     }
 
-    public function testDisplayRendersWithValidParamString()
+    public function testDisplayRendersWithValidParamString(): void
     {
         $params   = 'one=two,three=four';
         $expected = [
@@ -135,7 +135,7 @@ public function testDisplayRendersWithValidParamString()
         $this->assertSame(implode(',', $expected), $this->cell->render('\Tests\Support\View\SampleClass::echobox', $params));
     }
 
-    public function testDisplayRendersWithStaticMethods()
+    public function testDisplayRendersWithStaticMethods(): void
     {
         $params   = 'one=two,three=four';
         $expected = [
@@ -146,7 +146,7 @@ public function testDisplayRendersWithStaticMethods()
         $this->assertSame(implode(',', $expected), $this->cell->render('\Tests\Support\View\SampleClass::staticEcho', $params));
     }
 
-    public function testOptionsEmptyArray()
+    public function testOptionsEmptyArray(): void
     {
         $params   = [];
         $expected = [];
@@ -154,14 +154,14 @@ public function testOptionsEmptyArray()
         $this->assertSame(implode(',', $expected), $this->cell->render('\Tests\Support\View\SampleClass::staticEcho', $params));
     }
 
-    public function testOptionsNoParams()
+    public function testOptionsNoParams(): void
     {
         $expected = [];
 
         $this->assertSame(implode(',', $expected), $this->cell->render('\Tests\Support\View\SampleClass::staticEcho'));
     }
 
-    public function testCellEmptyParams()
+    public function testCellEmptyParams(): void
     {
         $params   = ',';
         $expected = 'Hello World';
@@ -169,7 +169,7 @@ public function testCellEmptyParams()
         $this->assertSame($expected, $this->cell->render('\Tests\Support\View\SampleClass::index', $params));
     }
 
-    public function testCellClassMissing()
+    public function testCellClassMissing(): void
     {
         $this->expectException(ViewException::class);
         $params   = 'one=two,three=four';
@@ -181,7 +181,7 @@ public function testCellClassMissing()
         $this->assertSame(implode(',', $expected), $this->cell->render('::echobox', $params));
     }
 
-    public function testCellMethodMissing()
+    public function testCellMethodMissing(): void
     {
         $this->expectException(ViewException::class);
         $params   = 'one=two,three=four';
@@ -193,7 +193,7 @@ public function testCellMethodMissing()
         $this->assertSame(implode(',', $expected), $this->cell->render('\Tests\Support\View\SampleClass::', $params));
     }
 
-    public function testCellBadClass()
+    public function testCellBadClass(): void
     {
         $this->expectException(ViewException::class);
         $params   = 'one=two,three=four';
@@ -202,7 +202,7 @@ public function testCellBadClass()
         $this->assertSame($expected, $this->cell->render('\CodeIgniter\View\GoodQuestion::', $params));
     }
 
-    public function testCellBadMethod()
+    public function testCellBadMethod(): void
     {
         $this->expectException(ViewException::class);
         $params   = 'one=two,three=four';
@@ -211,7 +211,7 @@ public function testCellBadMethod()
         $this->assertSame($expected, $this->cell->render('\Tests\Support\View\SampleClass::notThere', $params));
     }
 
-    public function testRenderCached()
+    public function testRenderCached(): void
     {
         $params   = 'one=two,three=four';
         $expected = [
@@ -224,7 +224,7 @@ public function testRenderCached()
         $this->assertSame(implode(',', $expected), $this->cell->render('\Tests\Support\View\SampleClass::echobox', $params, 1, 'rememberme'));
     }
 
-    public function testRenderCachedAutoName()
+    public function testRenderCachedAutoName(): void
     {
         $params   = 'one=two,three=four';
         $expected = [
@@ -239,7 +239,7 @@ public function testRenderCachedAutoName()
         $this->assertSame('six,five', $this->cell->render('\Tests\Support\View\SampleClass::echobox', $params, 1));
     }
 
-    public function testParametersMatch()
+    public function testParametersMatch(): void
     {
         $params = [
             'p1' => 'one',
@@ -251,7 +251,7 @@ public function testParametersMatch()
         $this->assertSame($expected, $this->cell->render('\Tests\Support\View\SampleClass::work', $params));
     }
 
-    public function testParametersDontMatch()
+    public function testParametersDontMatch(): void
     {
         $this->expectException(ViewException::class);
         $params   = 'p1=one,p2=two,p3=three';
@@ -260,7 +260,7 @@ public function testParametersDontMatch()
         $this->assertSame($expected, $this->cell->render('\Tests\Support\View\SampleClass::work', $params));
     }
 
-    public function testCallInitControllerIfMethodExists()
+    public function testCallInitControllerIfMethodExists(): void
     {
         $this->assertSame(
             Response::class,
@@ -268,7 +268,7 @@ public function testCallInitControllerIfMethodExists()
         );
     }
 
-    public function testLocateCellSuccess()
+    public function testLocateCellSuccess(): void
     {
         $this->assertSame('Hello World!', $this->cell->render('StarterCell::hello'));
         $this->assertSame('Hello CodeIgniter!', $this->cell->render('StarterCell::hello', ['name' => 'CodeIgniter']));
diff --git a/tests/system/View/ControlledCellTest.php b/tests/system/View/ControlledCellTest.php
index eee0e35b3194..2219371da9ea 100644
--- a/tests/system/View/ControlledCellTest.php
+++ b/tests/system/View/ControlledCellTest.php
@@ -32,42 +32,42 @@
  */
 final class ControlledCellTest extends CIUnitTestCase
 {
-    public function testCellRendersDefaultValues()
+    public function testCellRendersDefaultValues(): void
     {
         $result = view_cell(GreetingCell::class);
 
         $this->assertStringContainsString('Hello World', $result);
     }
 
-    public function testCellRendersViewWithActualClassName()
+    public function testCellRendersViewWithActualClassName(): void
     {
         $result = view_cell(AwesomeCell::class);
 
         $this->assertStringContainsString('Found!', $result);
     }
 
-    public function testCellWithNamedView()
+    public function testCellWithNamedView(): void
     {
         $result = view_cell(SimpleNotice::class);
 
         $this->assertStringContainsString('4, 8, 15, 16, 23, 42', $result);
     }
 
-    public function testCellThroughRenderMethod()
+    public function testCellThroughRenderMethod(): void
     {
         $result = view_cell(RenderedNotice::class);
 
         $this->assertStringContainsString('4, 8, 15, 16, 23, 42', $result);
     }
 
-    public function testCellThroughRenderMethodWithExtraData()
+    public function testCellThroughRenderMethodWithExtraData(): void
     {
         $result = view_cell(RenderedExtraDataNotice::class);
 
         $this->assertStringContainsString('42, 23, 16, 15, 8, 4', $result);
     }
 
-    public function testCellThrowsExceptionWhenCannotFindTheViewFile()
+    public function testCellThrowsExceptionWhenCannotFindTheViewFile(): void
     {
         $this->expectException(LogicException::class);
         $this->expectExceptionMessage('Cannot locate the view file for the "Tests\\Support\\View\\Cells\\BadCell" cell.');
@@ -75,7 +75,7 @@ public function testCellThrowsExceptionWhenCannotFindTheViewFile()
         view_cell(BadCell::class);
     }
 
-    public function testCellWithParameters()
+    public function testCellWithParameters(): void
     {
         $result = view_cell(GreetingCell::class, 'greeting=Hi, name=CodeIgniter');
 
@@ -87,14 +87,14 @@ public function testCellWithParameters()
         $this->assertStringContainsString('Hi CodeIgniter', $result);
     }
 
-    public function testCellWithCustomMethod()
+    public function testCellWithCustomMethod(): void
     {
         $result = view_cell('Tests\Support\View\Cells\GreetingCell::sayHello', 'greeting=Hi, name=CodeIgniter');
 
         $this->assertStringContainsString('Well, Hi CodeIgniter', $result);
     }
 
-    public function testCellWithMissingCustomMethod()
+    public function testCellWithMissingCustomMethod(): void
     {
         $this->expectException(ViewException::class);
         $this->expectExceptionMessage(lang('View.invalidCellMethod', [
@@ -105,14 +105,14 @@ public function testCellWithMissingCustomMethod()
         view_cell('Tests\Support\View\Cells\GreetingCell::sayGoodbye', 'greeting=Hi, name=CodeIgniter');
     }
 
-    public function testCellWithComputedProperties()
+    public function testCellWithComputedProperties(): void
     {
         $result = view_cell(ListerCell::class, ['items' => ['one', 'two', 'three']]);
 
         $this->assertStringContainsString('-one -two -three', $result);
     }
 
-    public function testCellWithPublicMethods()
+    public function testCellWithPublicMethods(): void
     {
         $result = view_cell(ColorsCell::class, ['color' => 'red']);
 
@@ -123,35 +123,35 @@ public function testCellWithPublicMethods()
         $this->assertStringContainsString('cool', $result);
     }
 
-    public function testMountingDefaultValues()
+    public function testMountingDefaultValues(): void
     {
         $result = view_cell(MultiplierCell::class);
 
         $this->assertStringContainsString('4', $result);
     }
 
-    public function testMountingCustomValues()
+    public function testMountingCustomValues(): void
     {
         $result = view_cell(MultiplierCell::class, ['value' => 3, 'multiplier' => 3]);
 
         $this->assertStringContainsString('9', $result);
     }
 
-    public function testMountValuesDefault()
+    public function testMountValuesDefault(): void
     {
         $result = view_cell(AdditionCell::class);
 
         $this->assertStringContainsString('2', $result);
     }
 
-    public function testMountValuesWithParams()
+    public function testMountValuesWithParams(): void
     {
         $result = view_cell(AdditionCell::class, ['value' => 3]);
 
         $this->assertStringContainsString('3', $result);
     }
 
-    public function testMountValuesWithParamsAndMountParams()
+    public function testMountValuesWithParamsAndMountParams(): void
     {
         $result = view_cell(AdditionCell::class, ['value' => 3, 'number' => 4, 'skipAddition' => false]);
 
@@ -162,7 +162,7 @@ public function testMountValuesWithParamsAndMountParams()
         $this->assertStringContainsString('3', $result);
     }
 
-    public function testMountWithMissingParams()
+    public function testMountWithMissingParams(): void
     {
         // Don't provide any params
         $result = view_cell(AdditionCell::class, ['value' => 3]);
diff --git a/tests/system/View/DecoratorsTest.php b/tests/system/View/DecoratorsTest.php
index 95b848d9f8a2..1297a8a6a912 100644
--- a/tests/system/View/DecoratorsTest.php
+++ b/tests/system/View/DecoratorsTest.php
@@ -39,7 +39,7 @@ protected function setUp(): void
         $this->config   = config('View');
     }
 
-    public function testNoDecoratorsDoesntAlter()
+    public function testNoDecoratorsDoesntAlter(): void
     {
         $config             = $this->config;
         $config->decorators = [];
@@ -53,7 +53,7 @@ public function testNoDecoratorsDoesntAlter()
         $this->assertStringContainsString($expected, $view->render('simple'));
     }
 
-    public function testThrowsOnInvalidClass()
+    public function testThrowsOnInvalidClass(): void
     {
         $this->expectException(ViewException::class);
         $this->expectExceptionMessage(lang('View.invalidDecoratorClass', [BadDecorator::class]));
@@ -70,7 +70,7 @@ public function testThrowsOnInvalidClass()
         $this->assertStringContainsString($expected, $view->render('simple'));
     }
 
-    public function testDecoratorAltersOutput()
+    public function testDecoratorAltersOutput(): void
     {
         $config             = $this->config;
         $config->decorators = [WorldDecorator::class];
@@ -84,7 +84,7 @@ public function testDecoratorAltersOutput()
         $this->assertStringContainsString($expected, $view->render('simple'));
     }
 
-    public function testParserNoDecoratorsDoesntAlter()
+    public function testParserNoDecoratorsDoesntAlter(): void
     {
         $config             = $this->config;
         $config->decorators = [];
@@ -96,7 +96,7 @@ public function testParserNoDecoratorsDoesntAlter()
         $this->assertSame("<h1>Hello World</h1>\n", $parser->render('template1'));
     }
 
-    public function testParserDecoratorAltersOutput()
+    public function testParserDecoratorAltersOutput(): void
     {
         $config             = $this->config;
         $config->decorators = [WorldDecorator::class];
diff --git a/tests/system/View/ParserFilterTest.php b/tests/system/View/ParserFilterTest.php
index 063c97acd972..7b41da6060fa 100644
--- a/tests/system/View/ParserFilterTest.php
+++ b/tests/system/View/ParserFilterTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void
         $this->config   = new View();
     }
 
-    public function testAbs()
+    public function testAbs(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -51,7 +51,7 @@ public function testAbs()
         $this->assertSame('55', $parser->renderString($template));
     }
 
-    public function testCapitalize()
+    public function testCapitalize(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -66,7 +66,7 @@ public function testCapitalize()
         $this->assertSame('Wonder Twins', $parser->renderString($template));
     }
 
-    public function testDate()
+    public function testDate(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -88,7 +88,7 @@ public function testDate()
         $this->assertSame("{$todayDash} {$todayDash} {$todayDot} {$todaySpace} {$todayColon} {$todaySlash} {$todayBackslash}", $parser->renderString($template));
     }
 
-    public function testDateModify()
+    public function testDateModify(): void
     {
         $parser    = new Parser($this->config, $this->viewsDir, $this->loader);
         $tommorrow = date('Y-m-d', strtotime('+1 day'));
@@ -104,7 +104,7 @@ public function testDateModify()
         $this->assertSame("{$tommorrow} {$tommorrow}", $parser->renderString($template));
     }
 
-    public function testDefault()
+    public function testDefault(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -120,7 +120,7 @@ public function testDefault()
         $this->assertSame('foo bar test', $parser->renderString($template));
     }
 
-    public function testEsc()
+    public function testEsc(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -137,7 +137,7 @@ public function testEsc()
         $this->assertSame("{$value1} {$value2}", $parser->renderString($template));
     }
 
-    public function testExcerpt()
+    public function testExcerpt(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -151,7 +151,7 @@ public function testExcerpt()
         $this->assertSame('... red fox jumped over ...', $parser->renderString($template));
     }
 
-    public function testHighlight()
+    public function testHighlight(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -165,7 +165,7 @@ public function testHighlight()
         $this->assertSame('The quick red fox <mark>jumped over</mark> the lazy brown dog', $parser->renderString($template));
     }
 
-    public function testHighlightCode()
+    public function testHighlightCode(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -184,7 +184,7 @@ public function testHighlightCode()
         $this->assertSame($expected, $parser->renderString($template));
     }
 
-    public function testProse()
+    public function testProse(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -198,7 +198,7 @@ public function testProse()
         $this->assertSame($expected, $parser->renderString($template));
     }
 
-    public function testLimitChars()
+    public function testLimitChars(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -212,7 +212,7 @@ public function testLimitChars()
         $this->assertSame('The quick&#8230;', $parser->renderString($template));
     }
 
-    public function testLimitWords()
+    public function testLimitWords(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -226,7 +226,7 @@ public function testLimitWords()
         $this->assertSame('The quick red fox&#8230;', $parser->renderString($template));
     }
 
-    public function testLower()
+    public function testLower(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -240,7 +240,7 @@ public function testLower()
         $this->assertSame('something', $parser->renderString($template));
     }
 
-    public function testNL2BR()
+    public function testNL2BR(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -254,7 +254,7 @@ public function testNL2BR()
         $this->assertSame("first<br>\nsecond", $parser->renderString($template));
     }
 
-    public function testNumberFormat()
+    public function testNumberFormat(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -268,7 +268,7 @@ public function testNumberFormat()
         $this->assertSame('1,098.35', $parser->renderString($template));
     }
 
-    public function testRound()
+    public function testRound(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -284,7 +284,7 @@ public function testRound()
         $this->assertSame('5.6 / 5.6 / 6 / 5 / 5.555', $parser->renderString($template));
     }
 
-    public function testStripTags()
+    public function testStripTags(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -298,7 +298,7 @@ public function testStripTags()
         $this->assertSame('Middle <b>Middle</b>', $parser->renderString($template));
     }
 
-    public function testTitle()
+    public function testTitle(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -312,7 +312,7 @@ public function testTitle()
         $this->assertSame('Though She Be Little', $parser->renderString($template));
     }
 
-    public function testUpper()
+    public function testUpper(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -326,7 +326,7 @@ public function testUpper()
         $this->assertSame('THOUGH SHE BE LITTLE', $parser->renderString($template));
     }
 
-    public function testLocalNumberBase()
+    public function testLocalNumberBase(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -340,7 +340,7 @@ public function testLocalNumberBase()
         $this->assertSame('1,234,567.8912', $parser->renderString($template));
     }
 
-    public function testLocalNumberPrecision()
+    public function testLocalNumberPrecision(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -354,7 +354,7 @@ public function testLocalNumberPrecision()
         $this->assertSame('1,234,567.89', $parser->renderString($template));
     }
 
-    public function testLocalNumberType()
+    public function testLocalNumberType(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -368,7 +368,7 @@ public function testLocalNumberType()
         $this->assertSame('one million two hundred thirty-four thousand five hundred sixty-seven point eight nine one two three four six', $parser->renderString($template));
     }
 
-    public function testLocalNumberLocale()
+    public function testLocalNumberLocale(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -382,7 +382,7 @@ public function testLocalNumberLocale()
         $this->assertSame('1.234.567,8912', $parser->renderString($template));
     }
 
-    public function testLocalCurrency()
+    public function testLocalCurrency(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -396,7 +396,7 @@ public function testLocalCurrency()
         $this->assertSame("1.234.567,89\u{a0}€", $parser->renderString($template));
     }
 
-    public function testLocalCurrencyWithoutFraction()
+    public function testLocalCurrencyWithoutFraction(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
@@ -410,7 +410,7 @@ public function testLocalCurrencyWithoutFraction()
         $this->assertSame("1.234.568\u{a0}€", $parser->renderString($template));
     }
 
-    public function testParsePairWithAbs()
+    public function testParsePairWithAbs(): void
     {
         $parser = new Parser($this->config, $this->viewsDir, $this->loader);
 
diff --git a/tests/system/View/ParserPluginTest.php b/tests/system/View/ParserPluginTest.php
index daea90de7fa7..53caa6389213 100644
--- a/tests/system/View/ParserPluginTest.php
+++ b/tests/system/View/ParserPluginTest.php
@@ -35,14 +35,14 @@ protected function setUp(): void
         $this->validator = Services::validation();
     }
 
-    public function testCurrentURL()
+    public function testCurrentURL(): void
     {
         $template = '{+ current_url +}';
 
         $this->assertSame(current_url(), $this->parser->renderString($template));
     }
 
-    public function testPreviousURL()
+    public function testPreviousURL(): void
     {
         $template = '{+ previous_url +}';
 
@@ -52,7 +52,7 @@ public function testPreviousURL()
         $this->assertSame(previous_url(), $this->parser->renderString($template));
     }
 
-    public function testMailto()
+    public function testMailto(): void
     {
         $template = '{+ mailto email=foo@example.com title=Silly +}';
 
@@ -62,28 +62,28 @@ public function testMailto()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3523
      */
-    public function testMailtoWithDashAndParenthesis()
+    public function testMailtoWithDashAndParenthesis(): void
     {
         $template = '{+ mailto email=foo-bar@example.com title="Online español test level" +}';
 
         $this->assertSame(mailto('foo-bar@example.com', 'Online español test level'), $this->parser->renderString($template));
     }
 
-    public function testSafeMailto()
+    public function testSafeMailto(): void
     {
         $template = '{+ safe_mailto email=foo@example.com title=Silly +}';
 
         $this->assertSame(safe_mailto('foo@example.com', 'Silly'), $this->parser->renderString($template));
     }
 
-    public function testLang()
+    public function testLang(): void
     {
         $template = '{+ lang Number.terabyteAbbr +}';
 
         $this->assertSame('TB', $this->parser->renderString($template));
     }
 
-    public function testValidationErrors()
+    public function testValidationErrors(): void
     {
         $this->validator->setError('email', 'Invalid email address');
 
@@ -92,7 +92,7 @@ public function testValidationErrors()
         $this->assertSame($this->setHints($this->validator->showError('email')), $this->setHints($this->parser->renderString($template)));
     }
 
-    public function testRoute()
+    public function testRoute(): void
     {
         // prime the pump
         $routes = service('routes');
@@ -105,14 +105,14 @@ public function testRoute()
         $this->assertSame('/path/string/to/13', $this->parser->renderString($template));
     }
 
-    public function testSiteURL()
+    public function testSiteURL(): void
     {
         $template = '{+ siteURL +}';
 
         $this->assertSame('http://example.com/index.php', $this->parser->renderString($template));
     }
 
-    public function testValidationErrorsList()
+    public function testValidationErrorsList(): void
     {
         $this->validator->setError('email', 'Invalid email address');
         $this->validator->setError('username', 'User name must be unique');
@@ -126,7 +126,7 @@ public function setHints($output)
         return preg_replace('/(<!-- DEBUG-VIEW+) (\w+) (\d+)/', '${1}', $output);
     }
 
-    public function testCspScriptNonceWithCspEnabled()
+    public function testCspScriptNonceWithCspEnabled(): void
     {
         $config             = config('App');
         $config->CSPEnabled = true;
diff --git a/tests/system/View/ParserTest.php b/tests/system/View/ParserTest.php
index d1bd13620470..5ad221cdca31 100644
--- a/tests/system/View/ParserTest.php
+++ b/tests/system/View/ParserTest.php
@@ -41,7 +41,7 @@ protected function setUp(): void
         $this->parser   = new Parser($this->config, $this->viewsDir, $this->loader);
     }
 
-    public function testSetDelimiters()
+    public function testSetDelimiters(): void
     {
         // Make sure default delimiters are there
         $this->assertSame('{', $this->parser->leftDelimiter);
@@ -62,13 +62,13 @@ public function testSetDelimiters()
         $this->assertSame('}', $this->parser->rightDelimiter);
     }
 
-    public function testParseSimple()
+    public function testParseSimple(): void
     {
         $this->parser->setVar('teststring', 'Hello World');
         $this->assertSame("<h1>Hello World</h1>\n", $this->parser->render('template1'));
     }
 
-    public function testParseString()
+    public function testParseString(): void
     {
         $data = [
             'title' => 'Page Title',
@@ -83,7 +83,7 @@ public function testParseString()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testParseStringMissingData()
+    public function testParseStringMissingData(): void
     {
         $data = [
             'title' => 'Page Title',
@@ -98,7 +98,7 @@ public function testParseStringMissingData()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testParseStringUnusedData()
+    public function testParseStringUnusedData(): void
     {
         $data = [
             'title' => 'Page Title',
@@ -114,12 +114,12 @@ public function testParseStringUnusedData()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testParseNoTemplate()
+    public function testParseNoTemplate(): void
     {
         $this->assertSame('', $this->parser->renderString(''));
     }
 
-    public function testParseArraySingle()
+    public function testParseArraySingle(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -137,7 +137,7 @@ public function testParseArraySingle()
         $this->assertSame("Super Heroes\nyes\nno", $this->parser->renderString($template));
     }
 
-    public function testParseArrayMulti()
+    public function testParseArrayMulti(): void
     {
         $data = [
             'powers' => [
@@ -154,7 +154,7 @@ public function testParseArrayMulti()
         $this->assertSame("yes\nno\nsecond: yes no", $this->parser->renderString($template));
     }
 
-    public function testParseArrayNested()
+    public function testParseArrayNested(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -178,7 +178,7 @@ public function testParseArrayNested()
         $this->assertSame("Super Heroes\nyes\nplane broomstick", $this->parser->renderString($template));
     }
 
-    public function testParseArrayNestedObject()
+    public function testParseArrayNestedObject(): void
     {
         $eagle       = new stdClass();
         $eagle->name = 'Baldy';
@@ -205,7 +205,7 @@ public function testParseArrayNestedObject()
         $this->assertSame('Owl and Class: stdClass work at Resource', $this->parser->renderString($template));
     }
 
-    public function testParseLoop()
+    public function testParseLoop(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -225,7 +225,7 @@ public function testParseLoop()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5825
      */
-    public function testParseLoopVariableWithParentheses()
+    public function testParseLoopVariableWithParentheses(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -242,7 +242,7 @@ public function testParseLoopVariableWithParentheses()
         $this->assertSame("Super Heroes\n(Tom) (Dick) (Henry) ", $this->parser->renderString($template));
     }
 
-    public function testParseLoopObjectProperties()
+    public function testParseLoopObjectProperties(): void
     {
         $obj1 = new stdClass();
         $obj2 = new stdClass();
@@ -267,7 +267,7 @@ public function testParseLoopObjectProperties()
         $this->assertSame("Super Heroes\nTom Dick Henry ", $this->parser->renderString($template));
     }
 
-    public function testParseIntegerPositive()
+    public function testParseIntegerPositive(): void
     {
         $data = [
             'title'  => 'Count:',
@@ -280,7 +280,7 @@ public function testParseIntegerPositive()
         $this->assertSame('Count: 5', $this->parser->renderString($template));
     }
 
-    public function testParseIntegerNegative()
+    public function testParseIntegerNegative(): void
     {
         $data = [
             'title'  => 'Count:',
@@ -293,7 +293,7 @@ public function testParseIntegerNegative()
         $this->assertSame('Count: -5', $this->parser->renderString($template));
     }
 
-    public function testParseFloatPositive()
+    public function testParseFloatPositive(): void
     {
         $data = [
             'title'  => 'Rate:',
@@ -306,7 +306,7 @@ public function testParseFloatPositive()
         $this->assertSame('Rate: 5.5', $this->parser->renderString($template));
     }
 
-    public function testParseFloatNegative()
+    public function testParseFloatNegative(): void
     {
         $data = [
             'title'  => 'Rate:',
@@ -319,7 +319,7 @@ public function testParseFloatNegative()
         $this->assertSame('Rate: -5.5', $this->parser->renderString($template));
     }
 
-    public function testParseNull()
+    public function testParseNull(): void
     {
         $data = [
             'title'  => 'Ticks:',
@@ -332,7 +332,7 @@ public function testParseNull()
         $this->assertSame('Ticks: ', $this->parser->renderString($template));
     }
 
-    public function testParseLoopEntityProperties()
+    public function testParseLoopEntityProperties(): void
     {
         $power = new class () extends Entity {
             public $foo    = 'bar';
@@ -362,7 +362,7 @@ public function toArray(bool $onlyChanged = false, bool $cast = true, bool $recu
         $this->assertSame("Super Heroes\n bar baz first second ", $this->parser->renderString($template));
     }
 
-    public function testParseLoopEntityObjectProperties()
+    public function testParseLoopEntityObjectProperties(): void
     {
         $power = new class () extends Entity {
             protected $attributes = [
@@ -399,7 +399,7 @@ public function __construct()
         $this->assertSame("Super Heroes\n bar baz first second ", $this->parser->renderString($template));
     }
 
-    public function testMismatchedVarPair()
+    public function testMismatchedVarPair(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -478,7 +478,7 @@ public function escValueTypes(): iterable
      * @param mixed      $value
      * @param mixed|null $expected
      */
-    public function testEscHandling($value, $expected = null)
+    public function testEscHandling($value, $expected = null): void
     {
         if ($expected === null) {
             $expected = $value;
@@ -489,7 +489,7 @@ public function testEscHandling($value, $expected = null)
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/3726
      */
-    public function testParseSimilarVariableNames()
+    public function testParseSimilarVariableNames(): void
     {
         $template = '{foo} {foo_bar}';
 
@@ -497,7 +497,7 @@ public function testParseSimilarVariableNames()
         $this->assertSame('bar foo-bar', $this->parser->renderString($template));
     }
 
-    public function testParsePairSimilarVariableNames()
+    public function testParsePairSimilarVariableNames(): void
     {
         $data = [
             'title'  => '<script>Heroes</script>',
@@ -517,7 +517,7 @@ public function testParsePairSimilarVariableNames()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/788
      */
-    public function testEscapingRespectsSetDataRaw()
+    public function testEscapingRespectsSetDataRaw(): void
     {
         $template = '{ foo }';
 
@@ -525,7 +525,7 @@ public function testEscapingRespectsSetDataRaw()
         $this->assertSame('<script>', $this->parser->renderString($template));
     }
 
-    public function testEscapingSetDataWithOtherContext()
+    public function testEscapingSetDataWithOtherContext(): void
     {
         $template = '{ foo }';
 
@@ -533,7 +533,7 @@ public function testEscapingSetDataWithOtherContext()
         $this->assertSame('http%3A%2F%2Ffoo.com', $this->parser->renderString($template));
     }
 
-    public function testNoEscapingSetData()
+    public function testNoEscapingSetData(): void
     {
         $template = '{ foo | noescape}';
 
@@ -541,20 +541,20 @@ public function testNoEscapingSetData()
         $this->assertSame('http://foo.com', $this->parser->renderString($template));
     }
 
-    public function testAutoEscaping()
+    public function testAutoEscaping(): void
     {
         $this->parser->setData(['foo' => 'http://foo.com'], 'unknown');
 
         $this->assertSame('html', $this->parser->shouldAddEscaping('{ foo | this | that }'));
     }
 
-    public function testAutoEscapingNot()
+    public function testAutoEscapingNot(): void
     {
         $this->parser->setData(['foo' => 'http://foo.com'], 'unknown');
         $this->assertFalse($this->parser->shouldAddEscaping('{ foo | noescape }'));
     }
 
-    public function testFilterWithNoArgument()
+    public function testFilterWithNoArgument(): void
     {
         $data = [
             'that_thing' => '<script>alert("ci4")</script>',
@@ -566,7 +566,7 @@ public function testFilterWithNoArgument()
         $this->assertSame('&lt;script&gt;alert(&quot;ci4&quot;)&lt;/script&gt;', $this->parser->renderString($template));
     }
 
-    public function testFilterWithArgument()
+    public function testFilterWithArgument(): void
     {
         $date = time();
 
@@ -580,7 +580,7 @@ public function testFilterWithArgument()
         $this->assertSame(date('Y-m-d', $date), $this->parser->renderString($template));
     }
 
-    public function testParserEscapesDataDefaultsToHTML()
+    public function testParserEscapesDataDefaultsToHTML(): void
     {
         $data = [
             'title'  => '<script>Heroes</script>',
@@ -594,7 +594,7 @@ public function testParserEscapesDataDefaultsToHTML()
         $this->assertSame('&lt;script&gt;Heroes&lt;/script&gt; &lt;a href=&#039;test&#039;&gt;Link&lt;/a&gt;', $this->parser->renderString($template));
     }
 
-    public function testParserNoEscape()
+    public function testParserNoEscape(): void
     {
         $data = [
             'title' => '<script>Heroes</script>',
@@ -605,7 +605,7 @@ public function testParserNoEscape()
         $this->assertSame('<script>Heroes</script>', $this->parser->renderString($template));
     }
 
-    public function testParserNoEscapeAndDelimiterChange()
+    public function testParserNoEscapeAndDelimiterChange(): void
     {
         $this->parser->setDelimiters('{{', '}}');
 
@@ -618,7 +618,7 @@ public function testParserNoEscapeAndDelimiterChange()
         $this->assertSame('<script>Heroes</script>', $this->parser->renderString($template));
     }
 
-    public function testIgnoresComments()
+    public function testIgnoresComments(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -637,7 +637,7 @@ public function testIgnoresComments()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testNoParse()
+    public function testNoParse(): void
     {
         $data = [
             'title'  => 'Super Heroes',
@@ -656,7 +656,7 @@ public function testNoParse()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testIfConditionalTrue()
+    public function testIfConditionalTrue(): void
     {
         $data = [
             'doit'     => true,
@@ -669,7 +669,7 @@ public function testIfConditionalTrue()
         $this->assertSame('HowdyWelcome', $this->parser->renderString($template));
     }
 
-    public function testElseConditionalFalse()
+    public function testElseConditionalFalse(): void
     {
         $data = [
             'doit' => true,
@@ -681,7 +681,7 @@ public function testElseConditionalFalse()
         $this->assertSame('Howdy', $this->parser->renderString($template));
     }
 
-    public function testElseConditionalTrue()
+    public function testElseConditionalTrue(): void
     {
         $data = [
             'doit' => false,
@@ -693,7 +693,7 @@ public function testElseConditionalTrue()
         $this->assertSame('Welcome', $this->parser->renderString($template));
     }
 
-    public function testElseifConditionalTrue()
+    public function testElseifConditionalTrue(): void
     {
         $data = [
             'doit'     => false,
@@ -706,7 +706,7 @@ public function testElseifConditionalTrue()
         $this->assertSame('Welcome', $this->parser->renderString($template));
     }
 
-    public function testConditionalBadSyntax()
+    public function testConditionalBadSyntax(): void
     {
         $this->expectException(ViewException::class);
         $data = [
@@ -721,13 +721,13 @@ public function testConditionalBadSyntax()
         $this->assertSame('HowdyWelcome', $this->parser->renderString($template));
     }
 
-    public function testWontParsePHP()
+    public function testWontParsePHP(): void
     {
         $template = "<?php echo 'Foo' ?> - <?= 'Bar' ?>";
         $this->assertSame('&lt;?php echo \'Foo\' ?&gt; - &lt;?= \'Bar\' ?&gt;', $this->parser->renderString($template));
     }
 
-    public function testParseHandlesSpaces()
+    public function testParseHandlesSpaces(): void
     {
         $data = [
             'title' => 'Page Title',
@@ -742,7 +742,7 @@ public function testParseHandlesSpaces()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testParseRuns()
+    public function testParseRuns(): void
     {
         $data = [
             'title' => 'Page Title',
@@ -757,7 +757,7 @@ public function testParseRuns()
         $this->assertSame($result, $this->parser->renderString($template));
     }
 
-    public function testCanAddAndRemovePlugins()
+    public function testCanAddAndRemovePlugins(): void
     {
         $this->parser->addPlugin('first', static fn ($str) => $str);
 
@@ -772,14 +772,14 @@ public function testCanAddAndRemovePlugins()
         $this->assertArrayNotHasKey('first', $setParsers);
     }
 
-    public function testParserPluginNoMatches()
+    public function testParserPluginNoMatches(): void
     {
         $template = 'hit:it';
 
         $this->assertSame('hit:it', $this->parser->renderString($template));
     }
 
-    public function testParserPluginNoParams()
+    public function testParserPluginNoParams(): void
     {
         $this->parser->addPlugin('hit:it', static fn ($str) => str_replace('here', 'Hip to the Hop', $str), true);
 
@@ -788,7 +788,7 @@ public function testParserPluginNoParams()
         $this->assertSame(' stuff Hip to the Hop ', $this->parser->renderString($template));
     }
 
-    public function testParserPluginClosure()
+    public function testParserPluginClosure(): void
     {
         $config                   = $this->config;
         $config->plugins['hello'] = static fn (array $params = []) => 'Hello, ' . trim($params[0]);
@@ -800,7 +800,7 @@ public function testParserPluginClosure()
         $this->assertSame('Hello, world', $this->parser->renderString($template));
     }
 
-    public function testParserPluginParams()
+    public function testParserPluginParams(): void
     {
         $this->parser->addPlugin('growth', static function ($str, array $params) {
             $step  = $params['step'] ?? 1;
@@ -820,7 +820,7 @@ public function testParserPluginParams()
         $this->assertSame(' 2 4 6 8', $this->parser->renderString($template));
     }
 
-    public function testParserSingleTag()
+    public function testParserSingleTag(): void
     {
         $this->parser->addPlugin('hit:it', static fn () => 'Hip to the Hop', false);
 
@@ -829,7 +829,7 @@ public function testParserSingleTag()
         $this->assertSame('Hip to the Hop', $this->parser->renderString($template));
     }
 
-    public function testParserSingleTagWithParams()
+    public function testParserSingleTagWithParams(): void
     {
         $this->parser->addPlugin('hit:it', static fn (array $params = []) => "{$params['first']} to the {$params['last']}", false);
 
@@ -838,7 +838,7 @@ public function testParserSingleTagWithParams()
         $this->assertSame('foo to the bar', $this->parser->renderString($template));
     }
 
-    public function testParserSingleTagWithSingleParams()
+    public function testParserSingleTagWithSingleParams(): void
     {
         $this->parser->addPlugin('hit:it', static fn (array $params = []) => "{$params[0]} to the {$params[1]}", false);
 
@@ -847,7 +847,7 @@ public function testParserSingleTagWithSingleParams()
         $this->assertSame('foo to the bar', $this->parser->renderString($template));
     }
 
-    public function testParserSingleTagWithQuotedParams()
+    public function testParserSingleTagWithQuotedParams(): void
     {
         $this->parser->addPlugin('count', static function (array $params = []) {
             $out = '';
@@ -864,7 +864,7 @@ public function testParserSingleTagWithQuotedParams()
         $this->assertSame('0. foo bar 1. baz 2. foo bar ', $this->parser->renderString($template));
     }
 
-    public function testParserSingleTagWithNamedParams()
+    public function testParserSingleTagWithNamedParams(): void
     {
         $this->parser->addPlugin('read_params', static function (array $params = []) {
             $out = '';
@@ -884,7 +884,7 @@ public function testParserSingleTagWithNamedParams()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/705
      */
-    public function testParseLoopWithDollarSign()
+    public function testParseLoopWithDollarSign(): void
     {
         $data = [
             'books' => [
@@ -950,7 +950,7 @@ public function testParseLoopWithHashInPrecession(): void
         $this->assertSame($expected, $this->parser->renderString($template));
     }
 
-    public function testCachedRender()
+    public function testCachedRender(): void
     {
         $this->parser->setVar('teststring', 'Hello World');
 
@@ -960,13 +960,13 @@ public function testCachedRender()
         $this->assertSame($expected, $this->parser->render('template1', ['cache' => 10, 'cache_name' => 'HelloWorld']));
     }
 
-    public function testRenderFindsView()
+    public function testRenderFindsView(): void
     {
         $this->parser->setData(['testString' => 'Hello World']);
         $this->assertSame("<h1>Hello World</h1>\n", $this->parser->render('Simpler'));
     }
 
-    public function testRenderCannotFindView()
+    public function testRenderCannotFindView(): void
     {
         $this->expectException(ViewException::class);
         $this->expectExceptionMessageMatches('!\AInvalid file: \"(?:.+)View(?:/|\\\\)Views(?:/|\\\\)Simplest\.php\"\z!');
@@ -975,7 +975,7 @@ public function testRenderCannotFindView()
         $this->parser->render('Simplest');
     }
 
-    public function testRenderSavingData()
+    public function testRenderSavingData(): void
     {
         $expected = "<h1>Hello World</h1>\n";
 
@@ -988,7 +988,7 @@ public function testRenderSavingData()
         $this->assertArrayHasKey('testString', $this->parser->getData());
     }
 
-    public function testRenderStringSavingData()
+    public function testRenderStringSavingData(): void
     {
         $expected = '<h1>Hello World</h1>';
         $pattern  = '<h1>{testString}</h1>';
@@ -1002,14 +1002,14 @@ public function testRenderStringSavingData()
         $this->assertArrayHasKey('testString', $this->parser->getData());
     }
 
-    public function testRenderFindsOtherView()
+    public function testRenderFindsOtherView(): void
     {
         $this->parser->setData(['testString' => 'Hello World']);
         $expected = '<h1>Hello World</h1>';
         $this->assertSame($expected, $this->parser->render('Simpler.html'));
     }
 
-    public function testChangedConditionalDelimitersTrue()
+    public function testChangedConditionalDelimitersTrue(): void
     {
         $this->parser->setConditionalDelimiters('{%', '%}');
 
@@ -1028,7 +1028,7 @@ public function testChangedConditionalDelimitersTrue()
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/5831
      */
-    public function testChangeConditionalDelimitersWorkWithJavaScriptCode()
+    public function testChangeConditionalDelimitersWorkWithJavaScriptCode(): void
     {
         $this->parser->setConditionalDelimiters('{%', '%}');
 
diff --git a/tests/system/View/TableTest.php b/tests/system/View/TableTest.php
index 6e56d2a3fe22..2c9bff35c4f0 100644
--- a/tests/system/View/TableTest.php
+++ b/tests/system/View/TableTest.php
@@ -34,7 +34,7 @@ protected function setUp(): void
 
     // Setter Methods
 
-    public function testSetTemplate()
+    public function testSetTemplate(): void
     {
         $this->assertFalse($this->table->setTemplate('not an array'));
 
@@ -44,13 +44,13 @@ public function testSetTemplate()
         $this->assertSame($template, $this->table->template);
     }
 
-    public function testSetEmpty()
+    public function testSetEmpty(): void
     {
         $this->table->setEmpty('nada');
         $this->assertSame('nada', $this->table->emptyCells);
     }
 
-    public function testSetCaption()
+    public function testSetCaption(): void
     {
         $this->table->setCaption('awesome cap');
         $this->assertSame('awesome cap', $this->table->caption);
@@ -59,7 +59,7 @@ public function testSetCaption()
     /**
      * @depends testPrepArgs
      */
-    public function testSetHeading()
+    public function testSetHeading(): void
     {
         // uses _prep_args internally, so we'll just do a quick
         // check to verify that func_get_args and prep_args are
@@ -77,7 +77,7 @@ public function testSetHeading()
         );
     }
 
-    public function testSetFooting()
+    public function testSetFooting(): void
     {
         // uses _prep_args internally, so we'll just do a quick
         // check to verify that func_get_args and prep_args are
@@ -96,7 +96,7 @@ public function testSetFooting()
         );
     }
 
-    public function testSetHeadingWithStyle()
+    public function testSetHeadingWithStyle(): void
     {
         $template = [
             'heading_cell_start' => '<td>',
@@ -122,7 +122,7 @@ public function testSetHeadingWithStyle()
         );
     }
 
-    public function testSetFootingWithStyle()
+    public function testSetFootingWithStyle(): void
     {
         $template = [
             'footing_cell_start' => '<td>',
@@ -151,7 +151,7 @@ public function testSetFootingWithStyle()
     /**
      * @depends testPrepArgs
      */
-    public function testAddRow()
+    public function testAddRow(): void
     {
         // uses _prep_args internally, so we'll just do a quick
         // check to verify that func_get_args and prep_args are
@@ -175,7 +175,7 @@ public function testAddRow()
 
     // Uility Methods
 
-    public function testPrepArgs()
+    public function testPrepArgs(): void
     {
         $expected = [
             ['data' => 'name'],
@@ -201,7 +201,7 @@ public function testPrepArgs()
         );
     }
 
-    public function testDefaultTemplateKeys()
+    public function testDefaultTemplateKeys(): void
     {
         $keys = [
             'table_open',
@@ -229,7 +229,7 @@ public function testDefaultTemplateKeys()
         }
     }
 
-    public function testCompileTemplate()
+    public function testCompileTemplate(): void
     {
         $this->assertFalse($this->table->setTemplate('invalid_junk'));
 
@@ -248,7 +248,7 @@ public function testCompileTemplate()
         $this->assertSame('</table junk>', $this->table->template['table_close']);
     }
 
-    public function testMakeColumns()
+    public function testMakeColumns(): void
     {
         // Test bogus parameters
         $this->assertFalse($this->table->makeColumns('invalid_junk'));
@@ -281,7 +281,7 @@ public function testMakeColumns()
         );
     }
 
-    public function testClear()
+    public function testClear(): void
     {
         $this->table->setHeading('Name', 'Color', 'Size');
 
@@ -309,7 +309,7 @@ public function testClear()
         $this->assertEmpty($this->table->rows);
     }
 
-    public function testSetFromArray()
+    public function testSetFromArray(): void
     {
         $data = [
             [
@@ -353,7 +353,7 @@ public function testSetFromArray()
         $this->assertSame($expected, $this->table->rows[1]);
     }
 
-    public function testSetFromObject()
+    public function testSetFromObject(): void
     {
         // This needs to be passed by reference to CI_DB_result::__construct()
         $dummy           = new stdClass();
@@ -379,7 +379,7 @@ public function testSetFromObject()
         $this->assertSame($expected, $this->table->rows[1]);
     }
 
-    public function testGenerate()
+    public function testGenerate(): void
     {
         // Prepare the data
         $data = [
@@ -445,7 +445,7 @@ public function testGenerate()
         $this->assertStringContainsString('<td>12345</td>', $table);
     }
 
-    public function testGenerateTdWithClassStyle()
+    public function testGenerateTdWithClassStyle(): void
     {
         $template = [
             'table_open'         => '<table border="1" cellpadding="4" cellspacing="0">',
@@ -494,7 +494,7 @@ public function testGenerateTdWithClassStyle()
         $this->assertStringContainsString('<td style="' . $this->styleTableTwo . '" class="thr"><small class="text-light">IDR <span class="badge badge-info">10</span></small></td>', $table);
     }
 
-    public function testGenerateThWithClassStyle()
+    public function testGenerateThWithClassStyle(): void
     {
         $template = [
             'table_open'         => '<table border="1" cellpadding="4" cellspacing="0">',
@@ -543,7 +543,7 @@ public function testGenerateThWithClassStyle()
         $this->assertStringContainsString('<th style="' . $this->styleTableTwo . '" class="thr"><small class="text-light">IDR <span class="badge badge-info">10</span></small></th>', $table);
     }
 
-    public function testGenerateInvalidHeadingFooting()
+    public function testGenerateInvalidHeadingFooting(): void
     {
         $template = [
             'table_open'         => '<table border="1" cellpadding="4" cellspacing="0">',
@@ -592,7 +592,7 @@ public function testGenerateInvalidHeadingFooting()
         $this->assertStringContainsString('<footer><small class="text-light">IDR <span class="badge badge-info">10</span></small></footer>', $table);
     }
 
-    public function testGenerateInvalidHeadingFootingHTML()
+    public function testGenerateInvalidHeadingFootingHTML(): void
     {
         $template = [
             'table_open'         => '<table border="1" cellpadding="4" cellspacing="0">',
@@ -641,7 +641,7 @@ public function testGenerateInvalidHeadingFootingHTML()
         $this->assertStringContainsString('td><small class="text-light">IDR <span class="badge badge-info">10</span></small></td>', $table);
     }
 
-    public function testGenerateEmptyCell()
+    public function testGenerateEmptyCell(): void
     {
         // Prepare the data
         $data = [
@@ -674,7 +674,7 @@ public function testGenerateEmptyCell()
         $this->assertStringContainsString('<td>Huh?</td>', $table);
     }
 
-    public function testWithConfig()
+    public function testWithConfig(): void
     {
         $customSettings = [
             'table_open' => '<table border="1" cellpadding="2" cellspacing="1" class="mytable">',
@@ -711,7 +711,7 @@ public function testWithConfig()
         $this->assertStringContainsString('<table border="1" cellpadding="2" cellspacing="1" class="mytable">', $generated);
     }
 
-    public function testGenerateFromDBResult()
+    public function testGenerateFromDBResult(): void
     {
         // This needs to be passed by reference to CI_DB_result::__construct()
         $dummy           = new stdClass();
@@ -730,7 +730,7 @@ public function testGenerateFromDBResult()
         $this->assertStringContainsString('<td>foo@bar.com</td>', $table);
     }
 
-    public function testUndefined()
+    public function testUndefined(): void
     {
         // Prepare the data
         $data = [];
@@ -740,7 +740,7 @@ public function testUndefined()
         $this->assertSame('Undefined table data', $table);
     }
 
-    public function testCallback()
+    public function testCallback(): void
     {
         $this->table->setHeading('Name', 'Color', 'Size');
         $this->table->addRow('Fred', '<strong>Blue</strong>', 'Small');
@@ -752,7 +752,7 @@ public function testCallback()
         $this->assertStringContainsString('<td>Fred</td><td>&lt;strong&gt;Blue&lt;/strong&gt;</td><td>Small</td>', $generated);
     }
 
-    public function testInvalidCallback()
+    public function testInvalidCallback(): void
     {
         $this->table->setHeading('Name', 'Color', 'Size');
         $this->table->addRow('Fred', '<strong>Blue</strong>', 'Small');
diff --git a/tests/system/View/ViewTest.php b/tests/system/View/ViewTest.php
index 537740231f66..2a9e161b56d3 100644
--- a/tests/system/View/ViewTest.php
+++ b/tests/system/View/ViewTest.php
@@ -38,7 +38,7 @@ protected function setUp(): void
         $this->config   = new Config\View();
     }
 
-    public function testSetVarStoresData()
+    public function testSetVarStoresData(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -47,7 +47,7 @@ public function testSetVarStoresData()
         $this->assertSame(['foo' => 'bar'], $view->getData());
     }
 
-    public function testSetVarOverwrites()
+    public function testSetVarOverwrites(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -57,7 +57,7 @@ public function testSetVarOverwrites()
         $this->assertSame(['foo' => 'baz'], $view->getData());
     }
 
-    public function testSetDataStoresValue()
+    public function testSetDataStoresValue(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -71,7 +71,7 @@ public function testSetDataStoresValue()
         $this->assertSame($expected, $view->getData());
     }
 
-    public function testSetDataMergesData()
+    public function testSetDataMergesData(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -90,7 +90,7 @@ public function testSetDataMergesData()
         $this->assertSame($expected, $view->getData());
     }
 
-    public function testSetDataOverwritesData()
+    public function testSetDataOverwritesData(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -108,7 +108,7 @@ public function testSetDataOverwritesData()
         $this->assertSame($expected, $view->getData());
     }
 
-    public function testSetVarWillEscape()
+    public function testSetVarWillEscape(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -117,7 +117,7 @@ public function testSetVarWillEscape()
         $this->assertSame(['foo' => 'bar&amp;'], $view->getData());
     }
 
-    public function testSetDataWillEscapeAll()
+    public function testSetDataWillEscapeAll(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -134,7 +134,7 @@ public function testSetDataWillEscapeAll()
         $this->assertSame($expected, $view->getData());
     }
 
-    public function testRenderFindsView()
+    public function testRenderFindsView(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -144,7 +144,7 @@ public function testRenderFindsView()
         $this->assertStringContainsString($expected, $view->render('simple'));
     }
 
-    public function testRenderString()
+    public function testRenderString(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -154,13 +154,13 @@ public function testRenderString()
         $this->assertSame($expected, $view->renderString('<h1><?= $testString ?></h1>'));
     }
 
-    public function testRenderStringNullTempdata()
+    public function testRenderStringNullTempdata(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
         $this->assertSame('test string', $view->renderString('test string'));
     }
 
-    public function testRendersThrowsExceptionIfFileNotFound()
+    public function testRendersThrowsExceptionIfFileNotFound(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -170,7 +170,7 @@ public function testRendersThrowsExceptionIfFileNotFound()
         $view->render('missing');
     }
 
-    public function testRenderScrapsData()
+    public function testRenderScrapsData(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -180,7 +180,7 @@ public function testRenderScrapsData()
         $this->assertEmpty($view->getData());
     }
 
-    public function testRenderCanSaveData()
+    public function testRenderCanSaveData(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -192,7 +192,7 @@ public function testRenderCanSaveData()
         $this->assertSame($expected, $view->getData());
     }
 
-    public function testRenderCanSaveDataThroughConfigSetting()
+    public function testRenderCanSaveDataThroughConfigSetting(): void
     {
         $this->config->saveData = true;
 
@@ -206,7 +206,7 @@ public function testRenderCanSaveDataThroughConfigSetting()
         $this->assertSame($expected, $view->getData());
     }
 
-    public function testCanDeleteData()
+    public function testCanDeleteData(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -218,7 +218,7 @@ public function testCanDeleteData()
         $this->assertSame([], $view->getData());
     }
 
-    public function testCachedRender()
+    public function testCachedRender(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -230,7 +230,7 @@ public function testCachedRender()
         $this->assertStringContainsString($expected, $view->render('simple', ['cache' => 10]));
     }
 
-    public function testRenderStringSavingData()
+    public function testRenderStringSavingData(): void
     {
         $view     = new View($this->config, $this->viewsDir, $this->loader);
         $expected = '<h1>Hello World</h1>';
@@ -245,7 +245,7 @@ public function testRenderStringSavingData()
         $this->assertArrayHasKey('testString', $view->getData());
     }
 
-    public function testPerformanceLogging()
+    public function testPerformanceLogging(): void
     {
         // Make sure debugging is on for our view
         $view = new View($this->config, $this->viewsDir, $this->loader, true);
@@ -257,7 +257,7 @@ public function testPerformanceLogging()
         $this->assertCount(1, $view->getPerformanceData());
     }
 
-    public function testPerformanceNonLogging()
+    public function testPerformanceNonLogging(): void
     {
         // Make sure debugging is on for our view
         $view = new View($this->config, $this->viewsDir, $this->loader, false);
@@ -269,7 +269,7 @@ public function testPerformanceNonLogging()
         $this->assertCount(0, $view->getPerformanceData());
     }
 
-    public function testRenderLayoutExtendsCorrectly()
+    public function testRenderLayoutExtendsCorrectly(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -279,7 +279,7 @@ public function testRenderLayoutExtendsCorrectly()
         $this->assertStringContainsString($expected, $view->render('extend'));
     }
 
-    public function testRenderLayoutExtendsMultipleCalls()
+    public function testRenderLayoutExtendsMultipleCalls(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -291,7 +291,7 @@ public function testRenderLayoutExtendsMultipleCalls()
         $this->assertStringContainsString($expected, $view->render('extend'));
     }
 
-    public function testRenderLayoutMakesDataAvailableToBoth()
+    public function testRenderLayoutMakesDataAvailableToBoth(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -301,7 +301,7 @@ public function testRenderLayoutMakesDataAvailableToBoth()
         $this->assertStringContainsString($expected, $view->render('extend'));
     }
 
-    public function testRenderLayoutSupportsMultipleOfSameSection()
+    public function testRenderLayoutSupportsMultipleOfSameSection(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -311,7 +311,7 @@ public function testRenderLayoutSupportsMultipleOfSameSection()
         $this->assertStringContainsString($expected, $view->render('extend_two'));
     }
 
-    public function testRenderLayoutWithInclude()
+    public function testRenderLayoutWithInclude(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -324,7 +324,7 @@ public function testRenderLayoutWithInclude()
         $this->assertSame(2, substr_count($content, 'Hello World'));
     }
 
-    public function testRenderLayoutBroken()
+    public function testRenderLayoutBroken(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -335,7 +335,7 @@ public function testRenderLayoutBroken()
         $this->assertStringContainsString($expected, $view->render('broken'));
     }
 
-    public function testRenderLayoutNoContentSection()
+    public function testRenderLayoutNoContentSection(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -345,7 +345,7 @@ public function testRenderLayoutNoContentSection()
         $this->assertStringContainsString($expected, $view->render('apples'));
     }
 
-    public function testRenderSaveDataCover()
+    public function testRenderSaveDataCover(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
         $this->setPrivateProperty($view, 'saveData', true);
@@ -354,7 +354,7 @@ public function testRenderSaveDataCover()
         $this->assertTrue($this->getPrivateProperty($view, 'saveData'));
     }
 
-    public function testRenderSaveDataUseAfterSaveDataFalse()
+    public function testRenderSaveDataUseAfterSaveDataFalse(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
         $view->setVar('testString', 'test');
@@ -363,7 +363,7 @@ public function testRenderSaveDataUseAfterSaveDataFalse()
         $this->assertStringContainsString('<h1>test</h1>', $view->render('simple', null, false));
     }
 
-    public function testCachedAutoDiscoverAndRender()
+    public function testCachedAutoDiscoverAndRender(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);
 
@@ -375,7 +375,7 @@ public function testCachedAutoDiscoverAndRender()
         $this->assertStringContainsString($expected, $view->render('Nested/simple', ['cache' => 10]));
     }
 
-    public function testRenderNestedSections()
+    public function testRenderNestedSections(): void
     {
         $view = new View($this->config, $this->viewsDir, $this->loader);