diff -u b/core/tests/Drupal/Tests/Core/Plugin/DefaultLazyPluginCollectionTest.php b/core/tests/Drupal/Tests/Core/Plugin/DefaultLazyPluginCollectionTest.php
--- b/core/tests/Drupal/Tests/Core/Plugin/DefaultLazyPluginCollectionTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/DefaultLazyPluginCollectionTest.php
@@ -233,8 +233,9 @@
     $this->assertSame(['value' => 'pineapple', 'id' => 'apple'], $plugin->getConfiguration());
 
     $this->defaultPluginCollection->setConfiguration(['cherry' => ['value' => 'kiwi', 'id' => 'cherry']]);
+    $expected['cherry'] = ['value' => 'kiwi', 'id' => 'cherry'];
     $config = $this->defaultPluginCollection->getConfiguration();
-    $this->assertSame(['cherry' => ['value' => 'kiwi', 'id' => 'cherry']], $config);
+    $this->assertSame($expected['cherry'], $config);
 
   }