diff -u b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityStorageTest.php b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityStorageTest.php
--- b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityStorageTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityStorageTest.php
@@ -512,6 +512,7 @@
     $config_object->get('id')->willReturn('foo');
     $config_object->isNew()->willReturn(FALSE);
     $config_object->getName()->willReturn('foo');
+    $config_object->hasOverrides()->willReturn(FALSE);
     $config_object->getCacheContexts()->willReturn([]);
     $config_object->getCacheTags()->willReturn(['config:foo']);
     $config_object->getCacheMaxAge()->willReturn(Cache::PERMANENT);