diff --git a/core/modules/system/tests/modules/theme_test/lib/Drupal/theme_test/ThemeTestController.php b/core/modules/system/tests/modules/theme_test/lib/Drupal/theme_test/ThemeTestController.php
index c790a84..06f3fce 100644
--- a/core/modules/system/tests/modules/theme_test/lib/Drupal/theme_test/ThemeTestController.php
+++ b/core/modules/system/tests/modules/theme_test/lib/Drupal/theme_test/ThemeTestController.php
@@ -31,4 +31,10 @@ function functionTemplateOverridden() {
     );
   }
 
+  /**
+   * Calls a theme hook suggestion.
+   */
+  function themeTestSuggestion() {
+    return theme(array('theme_test__suggestion', 'theme_test'), array());
+  }
 }
diff --git a/core/modules/system/tests/modules/theme_test/theme_test.module b/core/modules/system/tests/modules/theme_test/theme_test.module
index 40a78f3..f44e345 100644
--- a/core/modules/system/tests/modules/theme_test/theme_test.module
+++ b/core/modules/system/tests/modules/theme_test/theme_test.module
@@ -47,8 +47,7 @@ function theme_test_system_theme_info() {
 function theme_test_menu() {
   $items['theme-test/suggestion'] = array(
     'title' => 'Suggestion',
-    'page callback' => '_theme_test_suggestion',
-    'access callback' => TRUE,
+    'route_name' => 'theme_test_suggestion',
     'theme callback' => '_theme_custom_theme',
     'type' => MENU_CALLBACK,
   );
@@ -143,13 +142,6 @@ function _theme_test_alter() {
 }
 
 /**
- * Page callback, calls a theme hook suggestion.
- */
-function _theme_test_suggestion() {
-  return theme(array('theme_test__suggestion', 'theme_test'), array());
-}
-
-/**
  * Implements hook_preprocess_HOOK() for html.tpl.php.
  */
 function theme_test_preprocess_html(&$variables) {
diff --git a/core/modules/system/tests/modules/theme_test/theme_test.routing.yml b/core/modules/system/tests/modules/theme_test/theme_test.routing.yml
index 866171e..9f36108 100644
--- a/core/modules/system/tests/modules/theme_test/theme_test.routing.yml
+++ b/core/modules/system/tests/modules/theme_test/theme_test.routing.yml
@@ -4,3 +4,10 @@ function_template_override:
     _content: '\Drupal\theme_test\ThemeTestController::functionTemplateOverridden'
   requirements:
     _permission: 'access content'
+
+theme_test_suggestion:
+  pattern: 'theme-test/suggestion'
+  defaults:
+    _content: '\Drupal\theme_test\ThemeTestController::themeTestSuggestion'
+  requirements:
+    _access: 'TRUE'