public function testASignatureHashCanBeGeneratedFromBase64EncodedData()
 {
     $hashedSig = SignedRequest::hashSignature('WyJwYXlsb2FkIl0=', $this->appSecret);
     $expectedSig = base64_decode('bFofyO2sERX73y8uvuX26SLodv0mZ+Zk18d8b3zhD+s=');
     $this->assertEquals($expectedSig, $hashedSig);
 }