/**
  * @expectedException \Aws\Sns\Exception\InvalidSnsMessageException
  * @expectedExceptionMessage The message signature is invalid.
  */
 public function testValidateFailsWhenMessageIsInvalid()
 {
     $validator = new MessageValidator($this->getMockCertServerClient());
     $message = $this->getTestMessage(['Signature' => $this->getSignature('foo')]);
     $validator->validate($message);
 }