diff -u b/core/modules/color/tests/src/Functional/ColorTranslationPreviewTest.php b/core/modules/color/tests/src/Functional/ColorTranslationPreviewTest.php
--- b/core/modules/color/tests/src/Functional/ColorTranslationPreviewTest.php
+++ b/core/modules/color/tests/src/Functional/ColorTranslationPreviewTest.php
@@ -15,41 +15,51 @@
    * Modules to enable.
    *
-   * @var string[]
+   * @var array
    */
-  public static $modules = ['color', 'color_test'];
+  public static $modules = ['color', 'color_test', 'language', 'locale'];
 
   /**
-   * A user with administrative permissions.
+   * Profile to enable.
    *
-   * @var \Drupal\user\UserInterface
+   * @var string
    */
-  protected $bigUser;
+  protected $profile = 'standard';
 
   /**
    * {@inheritdoc}
    */
   protected function setUp() {
     parent::setUp();
-    // Create user.
-    $this->bigUser = $this->drupalCreateUser([
-      'administer themes',
-    ]);
-    $this->drupalLogin($this->bigUser);
-    // Install the color test theme.
-    \Drupal::service('theme_handler')->install(['color_test_theme']);
-    $this->config('system.theme')->set('default', 'color_test_theme')->save();
-    $this->rebuildContainer();
+    // Add a default locale storage.
+    $this->storage = $this->container->get('locale.storage');
   }
 
   /**
    * Ensuring the the text in the preview.html.twig file is wrapped with trans tag.
    */
   public function testTranslationPreview() {
-    // Markup is being printed from a Twig file located in:
-    // core/modules/color/tests/modules/color_test/themes/color_test_theme/color/preview.html.twig
-    $url_preview = 'core/modules/color/tests/modules/color_test/themes/color_test_theme/color/preview.html.twig';
-    $this->preview = file_get_contents($url_preview);
-    $this->assertRegExp('/{% trans %}/', $this->preview);
-    $this->assertRegExp('/{% endtrans %}/', $this->preview);
+    $account = $this->drupalCreateUser(['administer languages', 'administer themes']);
+    $this->drupalLogin($account);
+    // Add French language.
+    $edit = [
+      'predefined_langcode' => 'fr',
+    ];
+    $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add language'));
+    $this->rebuildContainer();
+    // Translate 'Example heading' to French ('Exemple de titre').
+    $source = $this->storage->createString([
+      'source' => 'Example heading',
+      'context' => '',
+    ])->save();
+    $this->storage->createTranslation([
+      'lid' => $source->lid,
+      'language' => 'fr',
+      'translation' => 'Exemple de titre',
+    ])->save();
+    //Checking the string 'Example heading' is translating to French.
+    $this->drupalGet('fr/admin/appearance/settings/bartik');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->pageTextContains('Exemple de titre');
+
   }
 }