PHPUnit_Framework_ExpectationFailedException::getComparisonFailure PHP Méthode

    public function getComparisonFailure()
    {
        return $this->comparisonFailure;
    }

 /**
  * @param Response $response
  * @param integer  $statusCode
  * @param string   $entityName
  * @param string   $requestType
  */
 protected function assertApiResponseStatusCodeEquals(Response $response, $statusCode, $entityName, $requestType)
 {
     try {
         $this->assertResponseStatusCodeEquals($response, $statusCode);
     } catch (\PHPUnit_Framework_ExpectationFailedException $e) {
         $e = new \PHPUnit_Framework_ExpectationFailedException(sprintf('Wrong %s response for "%s" request for entity: "%s". Error message: %s', $statusCode, $requestType, $entityName, $e->getMessage()), $e->getComparisonFailure());
         throw $e;
     }
 }