public function testContentDraftOnFlush()
 {
     $content = new MockContent();
     $this->assertNull($content->getDraft());
     $this->assertNull(self::$contentManager->getDraft($content));
     self::$em->persist($content);
     self::$em->flush($content);
     $this->assertNotNull($content->getDraft());
     $this->assertNotNull(self::$contentManager->getDraft($content));
     // Should create draft for content's elements that is instanceof BackBee\ClassContent\AbstractClassContent
     foreach ($content->getData() as $element) {
         if ($element instanceof AbstractClassContent) {
             $this->assertNotNull(self::$contentManager->getDraft($element));
         }
     }
 }