使用 LiveData Method getMainLooper 在 android.os.Looper 中进行单元测试

Question

我无法在尝试进行单元测试时使liveData.postValue工作。我一直在谷歌中检查解决方案，这就是我现在拥有的代码。

public class ProjectListViewModelTest {
    GetProjectList getProjectList = Mockito.mock(GetProjectList.class);
    ProjectModel.Project project = new ProjectModel.Project("testing",
            "this is a test",
            "https://logo.jpg",
            new ProjectModel.Company("cat"),
            "20150404",
            "active");
    List<ProjectModel.Project> projects = Arrays.asList(project);
    ProjectModel.ProjectList projectsList = new ProjectModel.ProjectList(projects);
    ProjectsListViewModel projectsListViewModel;
    private PublishSubject<ProjectModel.ProjectList> projectsListPublishSubject = PublishSubject.create();
    @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule();
    @BeforeClass
    public static void setUpRxSchedulers() {
        Scheduler immediate = new Scheduler() {
            @Override
            public Disposable scheduleDirect(@NonNull Runnable run, long delay, @NonNull TimeUnit unit) {
                return super.scheduleDirect(run, 0, unit);
            }
            @Override
            public Scheduler.Worker createWorker() {
                return new ExecutorScheduler.ExecutorWorker(Runnable::run);
            }
        };
        RxJavaPlugins.setInitIoSchedulerHandler(scheduler -> immediate);
        RxJavaPlugins.setInitComputationSchedulerHandler(scheduler -> immediate);
        RxJavaPlugins.setInitNewThreadSchedulerHandler(scheduler -> immediate);
        RxJavaPlugins.setInitSingleSchedulerHandler(scheduler -> immediate);
        RxAndroidPlugins.setInitMainThreadSchedulerHandler(scheduler -> immediate);
    }
    @Before
    @Throws(exceptionClasses = Exception.class)
    public void setUp() {
        MockitoAnnotations.initMocks(this);
        projectsListViewModel = new ProjectsListViewModel(getProjectList);
        when(getProjectList.execute()).thenReturn(projectsListPublishSubject.take(1).singleOrError());
    }
    @Test
    public void testExecuteGetProjectsListSuccess() {
        LiveData<List<ProjectModel.MapProject>> liveData = projectsListViewModel.getLiveData();
        ProjectModel.MapProject expectedResult = new ProjectModel.MapProject(
                "testing", "this is a test", "https://logo.jpg",
                "cat", "2015-04-04", "active");
        projectsListViewModel.getProjects();
        projectsListPublishSubject.onNext(projectsList);
        Assert.assertEquals(expectedResult, liveData.getValue().get(0));
    }
    @After
    public void tearDownClass(){
        RxAndroidPlugins.reset();
    }

我在setUpRxSchedulers中的代码是强制性的，以避免与 Rx 相同的错误(Method getMainLooper in android.os.Looper not mocked(。但是我无法解决调用 liveData.post(项目列表(时遇到的此错误。在我检查的所有论坛中，他们都说应该用@Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule();解决问题。但不是我的情况。

我也把视图模型放在这里，以防它有帮助：

public class ProjectsListViewModel extends ViewModel {
    GetProjectList getProjectList;
    MutableLiveData<List<ProjectModel.MapProject>> liveData = new MutableLiveData<>();
    public ProjectsListViewModel(GetProjectList getProjectList){
        this.getProjectList = getProjectList;
    }
    public LiveData<List<ProjectModel.MapProject>> getLiveData(){
        return liveData;
    }
    public void getProjects(){
        getProjectList.execute()
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
                .map(ProjectModel.ProjectList::getProjects)
                .toObservable().flatMapIterable(projects -> projects)
                .map(project -> project.convertToMapProject()).toList()
        .subscribe(projectsList ->
            liveData.setValue(projectsList));
    }
}

Answer 1

InstantTaskExecutorRule的使用实际上可以解决这个问题。

我认为问题是在 JUnit 5 中似乎不再支持@Rule注释(因为扩展现在是要走的路(。代码将成功编译，但不会应用规则。

对此(至少(有两种解决方案：

使用 JUnit 4

绝对是更快的，可能不是最好的，这取决于你需要多少JUnit 5。

只需将setup方法的注释从 @BeforeEach 更改为 @Before 并从 JUnit 4 导入@Test注释即可完成此操作。以下是导入的外观。

import org.junit.Before
import org.junit.Rule
import org.junit.Test

实现InstantTaskExecutorExtension

如果您关心使用 JUnit 5 :)，这会更好

这是一篇讨论如何精确实现的文章 InstantTaskExecutorExtension .完成后，请记住使用@ExtendWith(InstantTaskExecutorExtension::class)注释而不是@Rule将其应用于您的测试类！