diff -u b/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutLinksTest.php b/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutLinksTest.php
--- b/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutLinksTest.php
+++ b/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutLinksTest.php
@@ -70,7 +70,7 @@
 
     // Test that the 'add to Default shortcuts' works as expected.
     $this->drupalLogin($this->root_user);
-    theme_enable(array('seven'));
+    \Drupal::service('theme_handler')->enable(array('seven'));
     \Drupal::config('system.theme')->set('admin', 'seven')->save();
     $this->container->get('config.factory')->get('node.settings')->set('use_admin_theme', '1')->save();
     $this->drupalGet('admin/config/system/cron');
@@ -91,7 +91,7 @@
       $this->drupalGet($url_target);
     }
 
-    //Test if the shortcut is added correctly after going to a different page.
+    // Test if the shortcut is added correctly after going to a different page.
     $this->drupalGet('admin/structure');
     $this->assertLink('Cron', 0, 'Added Shortcut found on page');
   }