diff --git a/core/modules/node/lib/Drupal/node/Tests/NodeCreationTest.php b/core/modules/node/lib/Drupal/node/Tests/NodeCreationTest.php
index c5b4514f9f35b0b6384a931d7659f12e368b710c..540f95242af3ca84107d5a0b5444e03f97114463 100644
--- a/core/modules/node/lib/Drupal/node/Tests/NodeCreationTest.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeCreationTest.php
@@ -89,6 +89,8 @@ function testFailedPageCreation() {
     );
 
     try {
+      // An exception is generated by node_test_exception_node_insert() if the
+      // title is 'testing_transaction_exception'.
       entity_create('node', $edit)->save();
       $this->fail(t('Expected exception has not been thrown.'));
     }