Neos\Flow\Security\Cryptography\HashService::validateHmac PHP Method

    public function validateHmac($string, $hmac)
    {
        return $this->generateHmac($string) === $hmac;
    }

 /**
  * @test
  */
 public function generatedHashWillNotBeValidatedIfHashHasBeenChanged()
 {
     $string = 'asdf';
     $hash = 'myhash';
     $this->assertFalse($this->hashService->validateHmac($string, $hash));
 }