public function testSignature()
 {
     $client = new Client($this->configParams);
     $parameters['SellerId'] = $this->configParams['merchant_id'];
     $parameters['AWSAccessKeyId'] = $this->configParams['access_key'];
     $parameters['Version'] = 'test';
     $parameters['SignatureMethod'] = 'HmacSHA256';
     $parameters['SignatureVersion'] = 2;
     $parameters['Timestamp'] = $this->getFormattedTimestamp();
     uksort($parameters, 'strcmp');
     $signatureObj = new Signature($this->configParams, $parameters);
     $expectedSignature = $signatureObj->getSignature();
     $this->callPrivateMethod($client, 'createServiceUrl', null);
     $signature = $this->callPrivateMethod($client, 'signParameters', $parameters);
     $this->assertEquals($signature, $expectedSignature);
 }