reverted:
--- b/core/tests/Drupal/Tests/Core/Menu/LocalActionDefaultTest.php
+++ a/core/tests/Drupal/Tests/Core/Menu/LocalActionDefaultTest.php
@@ -16,7 +16,7 @@
  * @coversDefaultClass \Drupal\Core\Menu\LocalActionDefault
  * @group Menu
  */
+class LocalActionDefaultTest extends UnitTestCase {
-class 1LocalActionDefaultTest extends UnitTestCase {
 
   /**
    * The tested local action default plugin.