Android Studio 3.0 Beta2
我正在测试使用 RxJava2 获取端点列表。该应用程序在正常运行时运行良好。但是，当我使用 espresso 进行测试时，当我尝试 subscribeOn(scheduler) 时出现空指针异常。对于调度程序，我对注入(inject)的 subscribeOn 和 observeOn 使用了 trampoline()。
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'io.reactivex.Observable io.reactivex.Observable.subscribeOn(io.reactivex.Scheduler)' on a null object reference
为了使用 espresso 测试 RxJava2，对于 subscribeOn 和 observeOn 有什么我应该做的不同吗？
@Singleton
@Component(modules = {
MockNetworkModule.class,
MockAndroidModule.class,
MockExoPlayerModule.class
})
public interface TestBusbyBakingComponent extends BusbyBakingComponent {
TestRecipeListComponent add(MockRecipeListModule mockRecipeListModule);
}
这是我正在测试的类
public class RecipeListModelImp
implements RecipeListModelContract {
private RecipesAPI recipesAPI;
private RecipeSchedulers recipeSchedulers;
private CompositeDisposable compositeDisposable = new CompositeDisposable();
@Inject
public RecipeListModelImp(@NonNull RecipesAPI recipesAPI, @NonNull RecipeSchedulers recipeSchedulers) {
this.recipesAPI = Preconditions.checkNotNull(recipesAPI);
this.recipeSchedulers = Preconditions.checkNotNull(recipeSchedulers);
}
@Override
public void getRecipesFromAPI(final RecipeGetAllListener recipeGetAllListener) {
compositeDisposable.add(recipesAPI.getAllRecipes()
.subscribeOn(recipeSchedulers.getBackgroundScheduler()) /* NULLPOINTER EXCEPTION HERE */
.observeOn(recipeSchedulers.getUIScheduler())
.subscribeWith(new DisposableObserver<List<Recipe>>() {
@Override
protected void onStart() {}
@Override
public void onNext(@io.reactivex.annotations.NonNull List<Recipe> recipeList) {
recipeGetAllListener.onRecipeGetAllSuccess(recipeList);
}
@Override
public void onError(Throwable e) {
recipeGetAllListener.onRecipeGetAllFailure(e.getMessage());
}
@Override
public void onComplete() {}
}));
}
@Override
public void releaseResources() {
if(compositeDisposable != null && !compositeDisposable.isDisposed()) {
compositeDisposable.clear();
compositeDisposable.dispose();
}
}
}
调度程序的接口(interface)在这里，为了测试我正在使用注入(inject)的蹦床
@Module
public class MockAndroidModule {
@Singleton
@Provides
Context providesContext() {
return Mockito.mock(Context.class);
}
@Singleton
@Provides
Resources providesResources() {
return Mockito.mock(Resources.class);
}
@Singleton
@Provides
SharedPreferences providesSharedPreferences() {
return Mockito.mock(SharedPreferences.class);
}
@Singleton
@Provides
RecipeSchedulers provideRecipeSchedulers() {
return new RecipeSchedulers() {
@Override
public Scheduler getBackgroundScheduler() {
return Schedulers.trampoline();
}
@Override
public Scheduler getUIScheduler() {
return Schedulers.trampoline();
}
};
}
}
RecipleAPI 模拟模块
@Module
public class MockNetworkModule {
@Singleton
@Provides
public RecipesAPI providesRecipeAPI() {
return Mockito.mock(RecipesAPI.class);
}
}
组件是这样创建的
public class TestBusbyBakingApplication extends BusbyBakingApplication {
private TestBusbyBakingComponent testBusbyBakingComponent;
private TestRecipeListComponent testRecipeListComponent;
@Override
public TestBusbyBakingComponent createApplicationComponent() {
testBusbyBakingComponent = createTestBusbyBakingComponent();
testRecipeListComponent = createTestRecipeListComponent();
return testBusbyBakingComponent;
}
private TestBusbyBakingComponent createTestBusbyBakingComponent() {
testBusbyBakingComponent = DaggerTestBusbyBakingComponent.builder()
.build();
return testBusbyBakingComponent;
}
private TestRecipeListComponent createTestRecipeListComponent() {
testRecipeListComponent = testBusbyBakingComponent.add(new MockRecipeListModule());
return testRecipeListComponent;
}
}
对于 expresso 测试，我正在执行以下操作:
@RunWith(MockitoJUnitRunner.class)
public class RecipeListViewAndroidTest {
@Inject RecipesAPI recipesAPI;
@Mock RecipeListModelContract.RecipeGetAllListener mockRecipeListener;
@Rule
public ActivityTestRule<MainActivity> mainActivity =
new ActivityTestRule<>(
MainActivity.class,
true,
false);
@Before
public void setup() throws Exception {
Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
BusbyBakingApplication busbyBakingApplication =
(BusbyBakingApplication)instrumentation.getTargetContext().getApplicationContext();
TestBusbyBakingComponent component = (TestBusbyBakingComponent)busbyBakingApplication.createApplicationComponent();
component.add(new MockRecipeListModule()).inject(this);
}
@Test
public void shouldReturnAListOfRecipes() throws Exception {
List<Recipe> recipeList = new ArrayList<>();
Recipe recipe = new Recipe();
recipe.setName("Test Brownies");
recipe.setServings(10);
recipeList.add(recipe);
when(recipesAPI.getAllRecipes()).thenReturn(Observable.just(recipeList));
doNothing().when(mockRecipeListener).onRecipeGetAllSuccess(recipeList);
mainActivity.launchActivity(new Intent());
onView(withId(R.id.rvRecipeList)).check(matches(hasDescendant(withText("Test Brownies"))));
}
}
堆栈跟踪:
at me.androidbox.busbybaking.recipieslist.RecipeListModelImp.getRecipesFromAPI(RecipeListModelImp.java:37)
at me.androidbox.busbybaking.recipieslist.RecipeListPresenterImp.retrieveAllRecipes(RecipeListPresenterImp.java:32)
at me.androidbox.busbybaking.recipieslist.RecipeListView.getAllRecipes(RecipeListView.java:99)
at me.androidbox.busbybaking.recipieslist.RecipeListView.onCreateView(RecipeListView.java:80)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2192)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1299)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2013)
at android.support.v4.app.FragmentController.execPendingActions(FragmentController.java:388)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:607)
at android.support.v7.app.AppCompatActivity.onStart(AppCompatActivity.java:178)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1237)
at android.support.test.runner.MonitoringInstrumentation.callActivityOnStart(MonitoringInstrumentation.java:544)
at android.app.Activity.performStart(Activity.java:6268)
非常感谢您的任何建议，
最佳答案
您的代码库中存在许多问题。但首要的是以下内容:您正在以某种方式实例化新的真实对象(不是模拟对象)，这就是您获得 NPE 的原因，这与 subscribeOn() 无关。
您应该使测试组件从生产组件扩展。目前不是。
public interface TestRecipeListComponent extends RecipeListComponent {...}在您的测试应用程序类中，您正在混合回调，即您正在
createApplicationComponent回调中创建TestRecipeListComponent，但您有另一个回调来执行此操作:createRecipeListComponent()。您应该不模拟您的
MockRecipeListModule中的所有内容。只是模拟组件，你真的需要模拟。例如，如果您模拟RecipeAdapter，那么您为什么期望回收器 View 在屏幕上绘制任何东西？您只需要模拟数据源提供程序，在您的情况下是RecipeApi。除此之外，不应模拟任何内容，这不是单元测试，这是仪器测试。在
RecipeListView#onCreate()中，您正在创建一个新的RecipeListComponent，而您不应该，您应该获取该组件来自Application类，因为您已经在那里创建了它。这会影响测试:您无法从那里控制依赖项，因为RecipeListView只会忽略您从测试中更改的所有依赖项，并将创建一个提供其他依赖项的新组件，因此您的 stub 将 < strong>not 返回您在测试中明确硬编码的数据(事实上，它们甚至不会被调用，真正的对象会被调用)。这正是您遇到问题的原因。
我已经解决了所有这些问题。我已经到了你写的断言没有通过的地步。你应该不厌其烦地继续这个，因为它与你正在使用的逻辑/架构有关。
我已经打开了一个拉取请求 here .
关于android - 使用 Espresso 测试 RxJava2 并在 suscribeOn 时出现空指针异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45717803/