Braintree\Gateway::addOn PHP Метод

    public function addOn()
    {
        return new AddOnGateway($this);
    }

 /**
  * @expectedException Braintree\Exception\Configuration
  * @expectedExceptionMessage needs to be set (or accessToken needs to be passed to Braintree\Gateway).
  */
 public function testConfigGetsAssertedValid()
 {
     Braintree\Configuration::environment('development');
     //Braintree\Configuration::merchantId('integration_merchant_id');
     Braintree\Configuration::publicKey('integration_public_key');
     Braintree\Configuration::privateKey('integration_private_key');
     $gateway = new Braintree\Gateway(Braintree\Configuration::$global);
     $gateway->addOn();
 }