This subscriber listens to form events to automatically run filtering on the attached entity, like Validation is done.
Наследование: implements Symfony\Component\EventDispatcher\EventSubscriberInterface
 public function testAssertEventsBinding()
 {
     $bindedEvents = $this->listener->getSubscribedEvents();
     $this->assertArrayHasKey(FormEvents::POST_SUBMIT, $bindedEvents);
 }