Fix S3 adapter to use correct path separator and update related tests

src/Illuminate/Filesystem/AwsS3V3Adapter.php

@@ -6,6 +6,7 @@
 use Illuminate\Support\Traits\Conditionable;
 use League\Flysystem\FilesystemAdapter as FlysystemAdapter;
 use League\Flysystem\FilesystemOperator;
+use League\Flysystem\PathPrefixer;
 
 class AwsS3V3Adapter extends FilesystemAdapter
 {
@@ -31,6 +32,10 @@ public function __construct(FilesystemOperator $driver, FlysystemAdapter $adapte
         parent::__construct($driver, $adapter, $config);
 
         $this->client = $client;
+
+        $this->prefixer = isset($config['prefix'])
+            ? new PathPrefixer($this->prefixer->prefixPath($config['prefix']), '/')
+            : new PathPrefixer($config['root'] ?? '', '/');
     }
 
     /**

tests/Filesystem/FilesystemAdapterTest.php

@@ -715,6 +715,21 @@ public function testProvidesTemporaryUrlsForS3Adapter()
         $this->assertTrue($filesystemAdapter->providesTemporaryUrls());
     }
 
+    public function testUsesRightSeperatorForS3Adapter()
+    {
+        $filesystem = new FilesystemManager(new Application);
+        $filesystemAdapter = $filesystem->createS3Driver([
+            'region' => 'us-west-1',
+            'bucket' => 'laravel',
+            'root' => 'something',
+            'directory_separator' => '\\',
+        ]);
+
+        $path = $filesystemAdapter->path('different');
+        $this->assertStringContainsString('/', $path);
+        $this->assertStringNotContainsString('\\', $path);
+    }
+
     public function testProvidesTemporaryUrlsForAdapterWithoutTemporaryUrlSupport()
     {
         $filesystemAdapter = new FilesystemAdapter($this->filesystem, $this->adapter);