test: add test for regex error

Author: kenjis

tests/system/Autoloader/AutoloaderTest.php

@@ -17,6 +17,7 @@
 use Config\Modules;
 use Config\Services;
 use InvalidArgumentException;
+use RuntimeException;
 use UnnamespacedClass;
 
 /**
@@ -222,6 +223,16 @@ public function testSanitizationFilenameEdges()
         $this->loader->sanitizeFilename($test);
     }
 
+    public function testSanitizationRegexError()
+    {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('Malformed UTF-8 characters, possibly incorrectly encoded filename:');
+
+        $test = mb_convert_encoding('クラスファイル.php', 'EUC-JP', 'UTF-8');
+
+        $this->loader->sanitizeFilename($test);
+    }
+
     public function testSanitizationAllowUnicodeChars()
     {
         $test = 'Ä/path/to/some/file.php';