diff -u b/core/tests/Drupal/Tests/Core/Render/RendererTest.php b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
--- b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
@@ -126,7 +126,7 @@
       ],
       "This is <script>alert('XSS')</script> test",
     ];
-      // XSS filtering test.
+    // XSS filtering test.
     $data[] = [
       [
         'child' => [