Omnipay\PayPal\RestGateway::purchase PHP Method

    public function purchase(array $parameters = array())
    {
        return $this->createRequest('\\Omnipay\\PayPal\\Message\\RestPurchaseRequest', $parameters);
    }

 public function testPayWithSavedCard()
 {
     $this->setMockHttpResponse('RestCreateCardSuccess.txt');
     $response = $this->gateway->createCard($this->options)->send();
     $cardRef = $response->getCardReference();
     $this->setMockHttpResponse('RestPurchaseSuccess.txt');
     $response = $this->gateway->purchase(array('amount' => '10.00', 'cardReference' => $cardRef))->send();
     $this->assertTrue($response->isSuccessful());
     $this->assertEquals('44E89981F8714392Y', $response->getTransactionReference());
     $this->assertNull($response->getMessage());
 }