diff --git a/.editorconfig b/.editorconfig
index 3149f1c2..f1938bbd 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -4,5 +4,5 @@ trim_trailing_whitespace = true
 indent_style = space
 indent_size = 2
 
-[*.php]
+[{*.php, *.xml, *.xml.dist}]
 indent_size = 4
diff --git a/app/Http/Resources/AlbumResource.php b/app/Http/Resources/AlbumResource.php
index f10efc12..0e3860a2 100644
--- a/app/Http/Resources/AlbumResource.php
+++ b/app/Http/Resources/AlbumResource.php
@@ -23,7 +23,7 @@ class AlbumResource extends JsonResource
             'artist_name' => $this->album->artist->name,
             'cover' => $this->album->cover,
             'created_at' => $this->album->created_at,
-            'length' => $this->album->length,
+            'length' => (float) $this->album->length,
             'play_count' => (int) $this->album->play_count,
             'song_count' => (int) $this->album->song_count,
         ];
diff --git a/app/Providers/RouteServiceProvider.php b/app/Providers/RouteServiceProvider.php
index a4f9c549..27b04974 100644
--- a/app/Providers/RouteServiceProvider.php
+++ b/app/Providers/RouteServiceProvider.php
@@ -22,11 +22,25 @@ class RouteServiceProvider extends ServiceProvider
 
         Route::group([], base_path(sprintf('routes/%s.base.php', $type)));
 
-        $apiVersion = request()->header('X-Api-Version');
+        $apiVersion = self::getApiVersion();
         $routeFile = $apiVersion ? base_path(sprintf('routes/%s.%s.php', $type, $apiVersion)) : null;
 
         if ($routeFile && file_exists($routeFile)) {
             Route::group([], $routeFile);
         }
     }
+
+    private static function getApiVersion(): ?string
+    {
+        // In the test environment, the route service provider is loaded _before_ the request is made,
+        // so we can't rely on the header.
+        // Instead, we manually set the API version as an env variable in applicable test cases.
+        $version = app()->runningUnitTests() ? env('X_API_VERSION') : request()->header('X-Api-Version');
+
+        if ($version) {
+            Assert::oneOf($version, ['v6']);
+        }
+
+        return $version;
+    }
 }
diff --git a/tests/Feature/DownloadTest.php b/tests/Feature/DownloadTest.php
index d35215a9..9ca42ac4 100644
--- a/tests/Feature/DownloadTest.php
+++ b/tests/Feature/DownloadTest.php
@@ -16,8 +16,7 @@ use Mockery\MockInterface;
 
 class DownloadTest extends TestCase
 {
-    /** @var MockInterface|DownloadService */
-    private $downloadService;
+    private MockInterface|DownloadService $downloadService;
 
     public function setUp(): void
     {
diff --git a/tests/Feature/TestCase.php b/tests/Feature/TestCase.php
index 4884853d..e1abf418 100644
--- a/tests/Feature/TestCase.php
+++ b/tests/Feature/TestCase.php
@@ -12,8 +12,7 @@ abstract class TestCase extends BaseTestCase
     {
         /** @var User $user */
         $user = $user ?: User::factory()->create();
-        $headers['X-Requested-With'] = 'XMLHttpRequest';
-        $headers['Authorization'] = 'Bearer ' . $user->createToken('koel')->plainTextToken;
+        $this->withToken($user->createToken('koel')->plainTextToken);
 
         return parent::json($method, $uri, $data, $headers);
     }
diff --git a/tests/Feature/V6/AlbumTest.php b/tests/Feature/V6/AlbumTest.php
new file mode 100644
index 00000000..54a0df95
--- /dev/null
+++ b/tests/Feature/V6/AlbumTest.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace Tests\Feature\V6;
+
+use App\Models\Album;
+
+class AlbumTest extends TestCase
+{
+    private const JSON_STRUCTURE = [
+        'type',
+        'id',
+        'name',
+        'artist_id',
+        'artist_name',
+        'cover',
+        'created_at',
+        'length',
+        'play_count',
+        'song_count',
+    ];
+
+    private const JSON_COLLECTION_STRUCTURE = [
+        'data' => [
+            '*' => self::JSON_STRUCTURE,
+        ],
+    ];
+
+    public function testIndex(): void
+    {
+        Album::factory(10)->create();
+
+        $this->getAsUser('api/albums')
+            ->assertJsonStructure(self::JSON_COLLECTION_STRUCTURE);
+    }
+
+    public function testShow(): void
+    {
+        /** @var Album $album */
+        $album = Album::factory()->create();
+
+        $this->getAsUser('api/albums/' . $album->id)
+            ->assertJsonStructure(self::JSON_STRUCTURE);
+    }
+}
diff --git a/tests/Feature/V6/TestCase.php b/tests/Feature/V6/TestCase.php
new file mode 100644
index 00000000..1c9a9e3e
--- /dev/null
+++ b/tests/Feature/V6/TestCase.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Tests\Feature\V6;
+
+use Tests\Feature\TestCase as BaseTestCase;
+
+abstract class TestCase extends BaseTestCase
+{
+    public function setUp(): void
+    {
+        putenv('X_API_VERSION=v6');
+
+        parent::setUp();
+    }
+}