如何使用 Retrofit 2.0 和新的 MockRetrofit 类模拟服务？

Question

我们使用 Retrofit 1 来模拟 Web 服务并模拟网络延迟，如下所示：

MockRestAdapter mockRestAdapter = MockRestAdapter.from(restAdapter);
return mockRestAdapter.create(MyService.class, new MyServiceMock());

MyService 是服务接口（将响应作为 Rx Observables 返回），MyServiceMock 是实现此接口的类。

在 Retrofit 2.0.0-beta3 中，有一个全新的模拟系统（请参阅：https://github.com/square/retrofit/pull/1343）尚未记录。 当尝试做类似的事情时，我得到：

MockRetrofit mockRetrofit = new MockRetrofit.Builder(retrofit).build();
BehaviorDelegate<AuthService> delegate = mockRetrofit.create(MyService.class);

如何将呼叫转接到MyServiceMock？

Answer 1

假设接口定义如下：

public interface MyService {
    @GET("/name")
    rx.Observable<String> name();
}

呼叫将使用BehaviorDelegate 转接到MyServiceMock。 BehaviorDelegate 将 NetworkBehavior 应用于模拟创建的响应。请注意，下面的模拟实现将BehaviorDelegate 作为构造函数参数并使用它来返回响应。

public class MyServiceMock implements MyService {
    private final BehaviorDelegate<MyService> delegate;

    public MyServiceMock(BehaviorDelegate<MyService> delegate) {
        this.delegate = delegate;
    }

    public Observable<String> name() {
        return delegate.returningResponse("test").name();
    }
}

使用模拟服务的测试示例如下所示：

public class MyServiceTest {

    private final NetworkBehavior behavior = NetworkBehavior.create();
    private final rx.observers.TestSubscriber<String> testSubscriber = TestSubscriber.create();
    private MyService mockService;

    @Before
    public void setUp() throws Exception {
        Retrofit retrofit = new Retrofit.Builder()
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .baseUrl("http://example.com").build();

        MockRetrofit mockRetrofit = new MockRetrofit.Builder(retrofit)
                .networkBehavior(behavior).build();

        final BehaviorDelegate<MyService> delegate = mockRetrofit.create(MyService.class);

        mockService = new MyServiceMock(delegate);
    }

    @Test
    public void testSuccessResponse() throws Exception {
        givenNetworkFailurePercentIs(0);

        mockService.name().subscribe(testSubscriber);

        testSubscriber.assertValue("test");
        testSubscriber.assertCompleted();
    }

    @Test
    public void testFailureResponse() throws Exception {
        givenNetworkFailurePercentIs(100);

        mockService.name().subscribe(testSubscriber);

        testSubscriber.assertNoValues();
        testSubscriber.assertError(IOException.class);
    }

    private void givenNetworkFailurePercentIs(int failurePercent) {
        behavior.setDelay(0, MILLISECONDS);
        behavior.setVariancePercent(0);
        behavior.setFailurePercent(failurePercent);
    }
}