diff --git a/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php b/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
index 7d55719..0f68047 100644
--- a/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
+++ b/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
@@ -5,7 +5,7 @@
  * Contains \Drupal\Tests\Core\Template\TwigExtensionTest.
  */
 
-namespace Drupal\Tests\Core\Template;
+namespace Drupal\Tests\Core\Template {
 
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Render\RenderableInterface;
@@ -195,3 +195,16 @@ public function __toString() {
   }
 
 }
+
+}
+
+namespace {
+  if (!function_exists('t')) {
+    function t($string, array $args = []) {
+      return strtr($string, $args);
+    }
+  }
+  if (!function_exists('file_create_url')) {
+    function file_create_url() {}
+  }
+}