diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigSchemaTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigSchemaTest.php
index f15b612..6795fc1 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigSchemaTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigSchemaTest.php
@@ -648,7 +648,10 @@ public function testConfigSaveWithWrappingSchemaDoubleBrackets() {
       ->save();
     $tests = \Drupal::service('config.typed')->get('wrapping.config_schema_test.other_double_brackets')->get('tests')->getElements();
     $definition = $tests[0]->getDataDefinition()->toArray();
+    // Check that definition type is a merge of the expected types.
     $this->assertEqual($definition['type'], 'wrapping.test.other_double_brackets.*||test.double_brackets.cat:*.*');
+    // Check that breed was inherited from parent definition.
+    $this->assertEqual($definition['mapping']['breed'], ['type' => 'string']);
   }
 
 }