Omnipay\PayPal\RestGateway::authorize PHP Method

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

 public function testAuthorize()
 {
     $this->setMockHttpResponse('RestPurchaseSuccess.txt');
     $response = $this->gateway->authorize($this->options)->send();
     $this->assertTrue($response->isSuccessful());
     $this->assertEquals('44E89981F8714392Y', $response->getTransactionReference());
     $this->assertNull($response->getMessage());
 }