public function assert(RequestHelper $requestHelper)
 {
     if ($this->expectedJsonString) {
         $requestHelper->getTestCase()->assertJsonStringEqualsJsonString($this->expectedJsonString, $requestHelper->getClient()->getResponse()->getContent());
     }
     $data = $this->jsonDecode($requestHelper, false);
     foreach ($this->propertyHelpers as $propertyHelper) {
         $propertyHelper->assert($data);
     }
 }