diff --git a/core/modules/system/tests/modules/twig_extension_test/lib/Drupal/twig_extension_test/TwigExtensionTestController.php b/core/modules/system/tests/modules/twig_extension_test/lib/Drupal/twig_extension_test/TwigExtensionTestController.php
index 7869194..b4d74f7 100644
--- a/core/modules/system/tests/modules/twig_extension_test/lib/Drupal/twig_extension_test/TwigExtensionTestController.php
+++ b/core/modules/system/tests/modules/twig_extension_test/lib/Drupal/twig_extension_test/TwigExtensionTestController.php
@@ -26,16 +26,17 @@ public static function create(ContainerInterface $container) {
    * Menu callback for testing Twig filters in a Twig template.
    */
   public function testFilterRender() {
-    return theme('twig_extension_test_filter', array(
-      'message' => 'Every animal is not a mineral.',
-    ));
+    return array(
+      '#theme' => 'twig_extension_test_filter',
+      '#message' => 'Every animal is not a mineral.',
+    );
   }
 
   /**
    * Menu callback for testing Twig functions in a Twig template.
    */
   public function testFunctionRender() {
-    return theme('twig_extension_test_function');
+    return array('#theme' => 'twig_extension_test_function');
   }
 
 }
diff --git a/core/modules/system/tests/modules/twig_extension_test/twig_extension_test.module b/core/modules/system/tests/modules/twig_extension_test/twig_extension_test.module
index ae3723a..7e89470 100644
--- a/core/modules/system/tests/modules/twig_extension_test/twig_extension_test.module
+++ b/core/modules/system/tests/modules/twig_extension_test/twig_extension_test.module
@@ -1,6 +1,11 @@
 <?php
 
 /**
+ * @file
+ * Helper module for Twig extension tests.
+ */
+
+/**
  * Implements hook_theme().
  */
 function twig_extension_test_theme($existing, $type, $theme, $path) {
@@ -10,6 +15,7 @@ function twig_extension_test_theme($existing, $type, $theme, $path) {
       'template' => 'twig_extension_test.filter',
     ),
     'twig_extension_test_function' => array(
+      'render element' => 'element',
       'template' => 'twig_extension_test.function',
     ),
   );