public function testPurchaseFailure()
 {
     $httpResponse = $this->getMockHttpResponse('PurchaseFailure.txt');
     $response = new Response($this->getMockRequest(), $httpResponse->json());
     $this->assertFalse($response->isSuccessful());
     $this->assertFalse($response->isRedirect());
     $this->assertSame('ch_1IUAZQWFYrPooM', $response->getTransactionReference());
     $this->assertNull($response->getCardReference());
     $this->assertSame('Your card was declined', $response->getMessage());
     $this->assertNull($response->getSource());
 }