diff --git a/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php b/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php
index 50d299c..165c52f 100644
--- a/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php
+++ b/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php
@@ -368,18 +368,6 @@ protected function extensionConfig() {
   }
 
   /**
-   * Returns a given config object.
-   *
-   * @param string $name
-   *   The name of the config object to load.
-   *
-   * @return \Drupal\Core\Config\Config
-   */
-  protected function config($name) {
-    return $this->container->get('config.factory')->get($name);
-  }
-
-  /**
    * Returns the active configuration storage.
    *
    * @return \Drupal\Core\Config\ConfigStorageInterface
diff --git a/core/tests/Drupal/Tests/Core/DrupalTest.php b/core/tests/Drupal/Tests/Core/DrupalTest.php
index 39ffb57..4af023d 100644
--- a/core/tests/Drupal/Tests/Core/DrupalTest.php
+++ b/core/tests/Drupal/Tests/Core/DrupalTest.php
@@ -133,7 +133,7 @@ public function testConfig() {
       ->will($this->returnValue(TRUE));
     $this->setMockContainerService('config.factory', $config);
 
-    $this->assertNotNull($this->config('test_config'));
+    $this->assertNotNull(\Drupal::config('test_config'));
   }
 
   /**