如何模拟包中的响应?

我试图在使用时模拟响应 php-oppwa

我为这个包创建了这个包装:

use Bryangruneberg\OPPWA\Factory;
use Bryangruneberg\OPPWA\OPPWAResponse;
use Illuminate\Support\Facades\Config;

class OppwaService
{
    public function client()
    {
        $client = Factory::createClient(
            Config::get('gateways.oopwa_user_id'),
            Config::get('gateways.oopwa_password'),
            Config::get('gateways.oopwa_entity_id'),
            Config::get('gateways.oopwa_url'),
        );

        $api = Factory::createAPI($client);

        return $api;
    }

    public function setupCheckout(int $amount, string $currency, string $paymentType, array $options = [])
    {
        return $this->client()->prepareCheckout($amount, $currency, $paymentType, $options);
    }

    public function checkoutSetupWasSuccessful(OPPWAResponse $response)
    {
        return $this->client()->isPrepareCheckoutSuccess($response);
    }
}

我的控制器里有这个:

    public function __construct(OppwaService $service)
    {
        $this->service = $service;
    }

    public function show()
    {
        $checkout = $this->service->setupCheckout(23, 'USD', OPPWA::PAYMENT_TYPE_DEBIT);

        if ($this->service->checkoutSetupWasSuccessful($checkout)) {
            $checkoutId = $checkout->getId(); // I am trying to mock this response
        }

        return view('index',['checkoutId' => $checkoutId ?? null);
    }

我试图嘲笑 getId 在我的测试中,

    /** @test */
    public function checkout_id_exists()
    {
        $this->mock(OPPWAResponse::class, function ($mock) {
            $mock->shouldReceive('getId')->once()->andReturn('555555555-555555555');
        });

        $this->get(route('checkout.show'))->assertSee('555555555-555555555');
    }

但是,这行不通。是因为 OPPWAResponse 是在 vendor 目录? 我该如何嘲笑对方的回应?