Question

我是单元测试的新手，我使用rx android进行单元测试改造。我有一个observable从api获取访问令牌，我使用它来改造发送请求。我得到Null Pointer Exception，因为它是我的代码：

@RunWith(MockitoJUnitRunner.class)
public class AuthenticationTokenGetterTest {
    @Mock
    AuthenticatorInterface authenticatorservice;
    @InjectMocks
    AuthenticationTokenGetter tokengetter;

    @Test
    public void testtokkengetter() {
        when(authenticatorservice.servicecall(anyString(), anyString())).thenReturn(
                Observable.just("44fffffggggggg"));

        Observable<String> obs = tokengetter.getToken();
        TestSubscriber<String> testsubscriber = new TestSubscriber<>();
        obs.subscribe(testsubscriber);
        testsubscriber.assertNoErrors(); // Here I get exception
        List<String> value = testsubscriber.getOnNextEvents();
    }

}

但我一直都在收到java.lang.NullPointerException。我的可观察代码是我正在测试的：

@CheckResult
    public Observable<String> getToken() {
        return service.servicecall(key, code)
                .subscribeOn(Schedulers.newThread())
                .doOnNext(new Action1<String>() {
                    public void call(String token) {
                        savedToken = token;
                    }
                })
                .observeOn(AndroidSchedulers.mainThread());
    }

我的错误是：

java.lang.AssertionError: Unexpected onError events: 1

    at rx.observers.TestSubscriber.assertNoErrors(TestSubscriber.java:308)
    at AuthenticationTokenGetterTest.testtokkengetter(AuthenticationTokenGetterTest.java:47)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
    at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: java.lang.NullPointerException
    at rx.android.schedulers.LooperScheduler$HandlerWorker.schedule(LooperScheduler.java:77)
    at rx.android.schedulers.LooperScheduler$HandlerWorker.schedule(LooperScheduler.java:91)
    at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.schedule(OperatorObserveOn.java:190)
    at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber$1.request(OperatorObserveOn.java:147)
    at rx.Subscriber.setProducer(Subscriber.java:209)
    at rx.Subscriber.setProducer(Subscriber.java:205)
    at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.init(OperatorObserveOn.java:141)
    at rx.internal.operators.OperatorObserveOn.call(OperatorObserveOn.java:75)
    at rx.internal.operators.OperatorObserveOn.call(OperatorObserveOn.java:40)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:46)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.Observable.subscribe(Observable.java:8759)
    at rx.Observable.subscribe(Observable.java:8726)
.AuthenticationTokenGetterTest.testtokkengetter(AuthenticationTokenGetterTest.java:45)

Answer 1

你正在使用依赖于Android Looper类的AndroidSchedulers.mainThread()，这就是为什么空指针。不要创建使用多个线程的单元测试，在同一个线程上执行所有操作！

您可以通过执行调度程序注入来解决此问题。您的AuthenticationTokenGetter类应该通过构造函数中传递的mainThreadScheduler引用获取Scheduler实例，因此在您的普通代码中，您应该使用mainThreadScheduler创建对象，并在测试期间使用{创建对象{1}}同步执行所有内容的实现。

您也可以使用Scheduler来覆盖调度程序。

@edit 一些文章解释了如何注入/ ovveride调度程序：

https://medium.com/@peter.tackage/overriding-rxandroid-schedulers-in-rxjava-2-5561b3d14212

https://medium.com/@peter.tackage/an-alternative-to-rxandroidplugins-and-rxjavaplugins-scheduler-injection-9831bbc3dfaf

这两个解决方案都有它的优点和缺点，即使这些文章针对的是RxJava2，这种方法对RxJava1仍然有效（但是调度程序钩子/插件在Rx2中的工作方式略有不同）

Answer 2

我使用这种技术：

BaseSchedulerProvider（父亲）
ImmediateSchedulerProvider（测试）
SchedulerProvider（应用程序）

BaseSchedulerProvider：

public interface BaseSchedulerProvider {

    @NonNull
    Scheduler computation();

    @NonNull
    Scheduler io();

    @NonNull
    Scheduler ui();
}

ImmediateSchedulerProvider我用于测试：

public class ImmediateSchedulerProvider implements BaseSchedulerProvider {

    @NonNull
    @Override
    public Scheduler computation() {
        return Schedulers.immediate();
    }

    @NonNull
    @Override
    public Scheduler io() {
        return Schedulers.immediate();
    }

    @NonNull
    @Override
    public Scheduler ui() {
        return Schedulers.immediate();
    }
}

我在Presenter中使用的SchedulerProvider

public class SchedulerProvider implements BaseSchedulerProvider {

    // Prevent direct instantiation.
    public SchedulerProvider() {
    }

    @Override
    @NonNull
    public Scheduler computation() {
        return Schedulers.computation();
    }

    @Override
    @NonNull
    public Scheduler io() {
        return Schedulers.io();
    }

    @Override
    @NonNull
    public Scheduler ui() {
        return AndroidSchedulers.mainThread();
    }
}

在我的PresenterTest中，我设置如下：

public class TopicPresenterTest {

            @Mock
            private RemoteDataSource mRemoteDataSource;

            @Mock
            private TopicContract.View mView;

            private BaseSchedulerProvider mSchedulerProvider;

            TopicPresenter mPresenter;

            List<Topics> mList;

            @Before
            public void setup() {
            MockitoAnnotations.initMocks(this);

                    Topics topics = new Topics(1, "Discern The Beach");
                    Topics topicsTwo = new Topics(2, "Discern The Football Player");
                    mList = new ArrayList<>();
                    mList.add(topics);
                    mList.add(topicsTwo);
//ADD IMMEDIATESCHEDULERPROVIDER !!!!!!!!!!!!!!!
                    mSchedulerProvider = new 
                    ImmediateSchedulerProvider();

                    mPresenter = new TopicPresenter(mRemoteDataSource, mView, mSchedulerProvider);

            }

            @Test
            public void fetchData() {

                when(mRemoteDataSource.getTopicsRx())
                        .thenReturn(rx.Observable.just(mList));

                mThemePresenter.fetch();

                InOrder inOrder = Mockito.inOrder(mView);
                inOrder.verify(mView).setLoadingIndicator(false);
                inOrder.verify(mView).showTopics(mList);

            }

}

在我的演示者中

public class TopicPresenter {

        @NonNull
        private BaseSchedulerProvider mSchedulerProvider;

        public TopicPresenter(@NonNull RemoteDataSource remoteDataSource, @NonNull TopicContract.View view) {
                    this.mRemoteDataSource = checkNotNull(remoteDataSource, "remoteDataSource");
                    this.mView = checkNotNull(view, "view cannot be null!");
                    this.mSchedulerProvider = new SchedulerProvider();
 //ADD COMPOSITESUBSCRITPTION !!!!!!     
                    mSubscriptions = new CompositeSubscription();

                    mView.setPresenter(this);
        }
}

您可以查看my complete example in GitHub和this article.

使用改造和Rx android进行单元测试

2 个答案: