diff -u b/core/modules/system/tests/modules/entity_test/src/EntityTestForm.php b/core/modules/system/tests/modules/entity_test/src/EntityTestForm.php
--- b/core/modules/system/tests/modules/entity_test/src/EntityTestForm.php
+++ b/core/modules/system/tests/modules/entity_test/src/EntityTestForm.php
@@ -13,6 +13,8 @@
  */
 class EntityTestForm extends ContentEntityForm {
 
+  protected $validatedEntity;
+
   /**
    * {@inheritdoc}
    */
@@ -49,7 +51,6 @@
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
     $entity = parent::validateForm($form, $form_state);
-
     if (\Drupal::state()->get('test_ensure_saving_the_validated_entity')) {
       // Store the entity for comparision later in ::save.
       $this->validatedEntity = $entity;