Issue #2244087 by cs_shadow, andrei.dincu, joachim: Add explanation comment in NodeCreationTest

core/modules/node/lib/Drupal/node/Tests/NodeCreationTest.php

@@ -89,6 +89,8 @@ class NodeCreationTest extends NodeTestBase {
     );
 
     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.'));
     }