What is the right way to mock an RxJava Observable - android

I have an API which returns Observable's to be used with RxJava. For testing I want to avoid network operations so plan to mock the responses. However as all responses must me wrapped with Observable and the from() method expects a Future not a concrete type, my mock class is convoluted with anonymous wrapper classes and I think there must be a better way.
Here is what I have:
public class MockApi implements MyApi {
#Override
public Observable<MyData> getMyData() {
return Observable.from(new Future<MyData>() {
#Override public boolean cancel(boolean mayInterruptIfRunning) { return false; }
#Override public boolean isCancelled() { return false; }
#Override public boolean isDone() { return false; }
#Override
public MyData get(long timeout, TimeUnit unit) throws InterruptedException,
ExecutionException, TimeoutException {
return get();
}
#Override
public MyData get() throws InterruptedException, ExecutionException {
return new MyData();
}
});
}
...
}
Is there a better way?

return Observable.just(new MyData());
You can find the documentation here. And for more complicated mock => list of creating operators.

You can use Observable.defer(() -> Observable.just(new MyData()), or use PublishSubject for sending data through it. Notice, you have to use .defer() operator in first case because it will use the same value from first call otherwise

Related

Android paging works not as expected

I tried to use paging in my project. Unfortunately, it works not as I expected. I expected that the liveDataObserver will work after callBack.onResult.But in fact, the liveDataObserver observes immediately when the loadInitial finished.The callBack works later, and didn't post data to the observer.
The code:
First I wrote a class extend PageKeyedDataSource and interface SingleCreator
public class MyPagingDataSource<T> extends PageKeyedDataSource<Integer, T>
public interface SingleCreator<T> {
SingleSubscribeProxy<Page<T>> createSingle(int page, int pageSize);
}
Then the constructor of MyPagingDataSource:
public MyPagingDataSource(SingleCreator<T> singleCreator) {
this.singleCreator = singleCreator;
}
And override loadInitial:
#Override
public void loadInitial(#NonNull LoadInitialParams<Integer> params, #NonNull LoadInitialCallback<Integer, T> callback) {
singleCreator.createSingle(1, params.requestedLoadSize)
.subscribe(new SingleObserver<Page<T>>() {
#Override
public void onSubscribe(Disposable d) {
}
#Override
public void onSuccess(Page<T> ts) {
callback.onResult(ts.list, ts.pageNumber, ts.total, ts.pageNumber - 1, ts.pageNumber + 1);
Timber.d("registerLiveData" + ts.list.size());
}
#Override
public void onError(Throwable e) {
e.printStackTrace();
}
});
try {
//when I add this, observer will work after callback
//And if not observer works before callback.onResult
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
Then the datasourceFactory is just newInstanced in viewModel:
public LiveData<PagedList<MyData>> page = loadPageData();
public LiveData<PagedList<MyData>> loadPageData() {
return new LivePagedListBuilder<>(new DataSource.Factory<Integer, MyData>() {
#Override
public DataSource<Integer, MyData> create() {
return new HBPagingDataSource<>((page, pageSize) -> loadPageSingle(page, pageSize));
}
}, 2).build();
}
the single
private SingleSubscribeProxy<Page<MyData>> loadPageSingle(int pageNum, int pageSize) {
return mModel.loadMyDates(pageNum, pageSize)
.doOnError(Throwable::printStackTrace)
.as(autoDisposable(this));
}
at fragment
mViewModel.page.observe(this, myDatas -> {
Timber.d("registerLiveData%s", myDatas.size());
myAdapter.submitList(myDatas);
});
Maybe related things:
I wrote subscribeOn and observeOn in retrofit's callAdapter
The viewModel is a scopeProvider since I'm using autoDispose
I tried some example in github. And it seems, the setValue for pageLivedata is always work after loadInitial. In this case, how can I use single?
It's seems solved.
The error is because schedule the thread using rxjava.
It makes single and datasource work in different thread.
In this case, callback onResult run after the observer.
So, I updated the callAdapter where I wrote subscribeOn and observeOn for single.
Filter by className when It's Page class, it won't do subscribeOn and observeOn.
Now the conclusion is, let paging handle the thread.

Mockito unit test BaseObserver and static method with context

I am facing with Unit testing for the first time and I would like to know what is the best approach for the following scenario.
I am using Mockito for the tests. The following test is for logic(Presenter) layer and I am trying to verify certain behaviors of the view.
App classes
The method of the Presenter that need to be include in the test:
public void loadWeather() {
CityDetailsModel selectedCity = getDbHelper().getSelectedCityModel();
if (selectedCity != null) {
getCompositeDisposableHelper().execute(
getApiHelper().weatherApiRequest(selectedCity.getLatitude(), selectedCity.getLongitude()),
new WeatherObserver(getMvpView()));
} else {
getMvpView().showEmptyView();
}
}
WeatherObserver:
public class WeatherObserver extends BaseViewSubscriber<DayMvpView, WeatherResponseModel> {
public WeatherObserver(DayMvpView view) {
super(view);
}
#Override public void onNext(WeatherResponseModel weatherResponseModel) {
super.onNext(weatherResponseModel);
if (weatherResponseModel.getData().isEmpty()) {
getMvpView().showEmptyView();
} else {
getMvpView().showWeather(weatherResponseModel.getData());
}
}
}
BaseViewSubscriber (Default DisposableObserver base class to be used whenever we want default error handling):
public class BaseViewSubscriber<V extends BaseMvpView, T> extends DisposableObserver<T> {
private ErrorHandlerHelper errorHandlerHelper;
private V view;
public BaseViewSubscriber(V view) {
this.view = view;
errorHandlerHelper = WeatherApplication.getApplicationComponent().errorHelper();
}
public V getView() {
return view;
}
public boolean shouldShowError() {
return true;
}
protected boolean shouldShowLoading() {
return true;
}
#Override public void onStart() {
if (!AppUtils.isNetworkAvailable(WeatherApplication.getApplicationComponent().context())) {
onError(new InternetConnectionException());
return;
}
if (shouldShowLoading()) {
view.showLoading();
}
super.onStart();
}
#Override public void onError(Throwable e) {
if (view == null) {
return;
}
if (shouldShowLoading()) {
view.hideLoading();
}
if (shouldShowError()) {
view.onError(errorHandlerHelper.getProperErrorMessage(e));
}
}
#Override public void onComplete() {
if (view == null) {
return;
}
if (shouldShowLoading()) {
view.hideLoading();
}
}
#Override public void onNext(T t) {
if (view == null) {
return;
}
}
}
CompositeDisposableHelper (CompositeDisposable helper class):
public class CompositeDisposableHelper {
public CompositeDisposable disposables;
public TestScheduler testScheduler;
#Inject public CompositeDisposableHelper(CompositeDisposable disposables) {
this.disposables = disposables;
testScheduler = new TestScheduler();
}
public <T> void execute(Observable<T> observable, DisposableObserver<T> observer) {
addDisposable(observable.subscribeOn(testScheduler)
.observeOn(testScheduler)
.subscribeWith(observer));
}
public void dispose() {
if (!disposables.isDisposed()) {
disposables.dispose();
}
}
public TestScheduler getTestScheduler() {
return testScheduler;
}
public void addDisposable(Disposable disposable) {
disposables.add(disposable);
}
}
My test:
#Test public void loadSuccessfully() {
WeatherResponseModel responseModel = new WeatherResponseModel();
List<WeatherModel> list = new ArrayList<>();
list.add(new WeatherModel());
responseModel.setData(list);
CityDetailsModel cityDetailsModel = new CityDetailsModel();
cityDetailsModel.setLongitude("");
cityDetailsModel.setLatitude("");
when(dbHelper.getSelectedCityModel()).thenReturn(cityDetailsModel);
when(apiHelper.weatherApiRequest(anyString(), anyString())).thenReturn(
Observable.just(responseModel));
dayPresenter.loadWeather();
compositeDisposableHelper.getTestScheduler().triggerActions();
verify(dayMvpView).showWeather(list);
verify(dayMvpView, never()).showEmptyView();
verify(dayMvpView, never()).onError(anyString());
}
When I try to run the test, I get NullPointer, because new WeatherObserver(getMvpView()) is called, and in the BaseViewSubscriber errorHandlerHelper is null because getApplicationCopomnent is null.
As well NullPointer is thrown in the static method AppUtils.isNetworkAvailable() for the same reason.
When I try to comment these lines, the test is OK.
My questions are:
Should I use Dagger for the Unit test as well or? If yes please give
me example for my test.
Should I use PowerMockito for the static method
AppUtils.isNetworkAvailable()? If yes, is it ok just because of
this method to use PowerMockito Runner
#RunWith(PowerMockRunner.class)?
Should I use Dagger for the Unit test as well or? If yes please give me example for my test.
You don't have to use Dagger necessarily at the test, but that's where Dependency Injection will benefit you, as it will help you strip your dependencies out, and tests will be able to replace them.
Should I use PowerMockito for the static method AppUtils.isNetworkAvailable()? If yes, is it ok just because of this method to use PowerMockito Runner
#RunWith(PowerMockRunner.class)?
Static methods are generally bad for testing, as you cannot replace them (at least not easily and without PowerMock) for testing purposes.
The better practice is to use Dagger for the production code to inject those dependencies, preferably at Constructor, so at tests you can simply provide those dependencies according to test needs (using mocks or fakes where necessary).
In your case, you can add both ErrorHandlerHelper and AppUtils to BaseViewSubscriber Constructor. as BaseViewSubscriber shouldn't be injected, you will need to provide those modules to it from outside, in the presenter, that where you should use Injection to get those Objects. again at the Constructor.
At test, simply replace or provide this objects to the presenter that in it's turn will hand it over to the BaseViewSubscriber.
You can read more about tests seams at android here.
Besides that, it some very odd to me the OO hierarchy of Observer and Disposable that wraps the Observable for getting common behavior, it's essentially breaking the functional stream oriented reactive approach, you might want to consider using patterns like compose using Transformers and using doOnXXX operators do apply common behavior at reactive streams.

How to combine Espresso with IdlingResource with RxJava's Subject

I have a problem with combining Google's Espresso test automation library.
In production code the following transformer to apply Schedulers to Observable is used:
public SCProductionUiSchedulersTransformer() {
schedulersTransformer = new Observable.Transformer() {
#Override
public Object call(Object observable) {
return ((Observable) observable)
.subscribeOn(rxFactory.getIoScheduler())
.observeOn(rxFactory.getMainThreadScheduler());
}
};
}
In Espresso automation tests the following is used:
public <T> SCIdlingUiSchedulersTransformer(Context context, final CountingIdlingResource countingIdlingResource) {
schedulersTransformer = new Observable.Transformer<T, T>() {
#Override
public Observable<T> call(Observable<T> observable) {
return observable
.subscribeOn(rxFactory.getIoScheduler())
.observeOn(rxFactory.getMainThreadScheduler())
.doOnSubscribe(new Action0() {
#Override
public void call() {
countingIdlingResource.increment();
}
})
.doOnTerminate(new Action0() {
#Override
public void call() {
countingIdlingResource.decrement();
}
});
}
};
}
CountingIdlingResource is the regular Espresso one used to inform automation Thread that application is not idle and it has to wait for the operation to complete.
For regular Observable the following code works without problems.
The problem is with Observable of type Subject. Of course it does not work, because subscription to Subject is made on Activity start and causes the automation Thread to hang.
Is there any way to align the code to make it work for Subject? Maybe detecting that observable is of type Subject?

Verify mock interactions within anonymous inner class

I am trying to test my ViewModel in my application, here is the constructor:
#Inject
public SearchUserViewModel(#Named("searchUser") UseCase searchUserUseCase) {
this.searchUserUseCase = searchUserUseCase;
}
In my test I create a SearchUserUseCase with mocks like this:
Observable error = Observable.error(new Throwable("Error"));
when(gitHubService.searchUser(MockFactory.TEST_USERNAME_ERROR)).thenReturn(error);
when(ObserverThread.getScheduler()).thenReturn(Schedulers.immediate());
when(SubscriberThread.getScheduler()).thenReturn(Schedulers.immediate());
searchUserUseCase = new SearchUserUseCase(gitHubService, SubscriberThread, ObserverThread);
In my ViewModel class I have this snippet which I want to test:
public void onClickSearch(View view) {
loadUsers();
}
private void loadUsers() {
if (username == null) {
fragmentListener.showMessage("Enter a username");
} else {
showProgressIndicator(true);
searchUserUseCase.execute(new SearchUserSubscriber(), username);
}
}
private final class SearchUserSubscriber extends DefaultSubscriber<SearchResponse> {
#Override
public void onCompleted() {
showProgressIndicator(false);
}
#Override
public void onError(Throwable e) {
showProgressIndicator(false);
fragmentListener.showMessage("Error loading users");
}
#Override
public void onNext(SearchResponse searchResponse) {
List<User> users = searchResponse.getUsers();
if (users.isEmpty()) {
fragmentListener.showMessage("No users found");
} else {
fragmentListener.addUsers(users);
}
}
}
Finally in my test I have this:
#Test
public void shouldDisplayErrorMessageIfErrorWhenLoadingUsers() {
SearchUserViewModel searchUserViewModel = new SearchUserViewModel(searchUserUseCase);
searchUserViewModel.setFragmentListener(mockFragmentListener);
searchUserViewModel.setUsername(MockFactory.TEST_USERNAME_ERROR);
searchUserViewModel.onClickSearch(view);
verify(mockFragmentListener).showMessage("Error loading users");
}
I get this error from Mockito:
Wanted but not invoked:
fragmentListener.showMessage(
"Error loading users"
);
I am not sure if this is a good test, but I somehow want to test the SearchUserSubscriber one way or another. Thanks
Edit: I have found similar questions to this problem here: Can't verify mock method call from RxJava Subscriber (which still isn't answered) and here: Verify interactions in rxjava subscribers. The latter question is similar but does not execute the subscriber in a separate class (which happens in SearchUserUseCase here).
I also tried RobolectricGradleTestRunner instead of MockitoJunitRunner and changed to Schedulers.io() and AndroidSchedulers.mainThread(), but I still get the same error.
Tried mocking SearchUserUseCase instead of GitHubService (which feels cleaner), but I'm not sure on how to test the subscriber that way since that is passed as an argument to the void method execute() in UseCase.
public void execute(Subscriber useCaseSubscriber, String query) {
subscription = buildUseCase(query)
.observeOn(postExecutionThread.getScheduler())
.subscribeOn(threadExecutor.getScheduler())
.subscribe(useCaseSubscriber);
}
And buildUseCase()
#Override
public Observable buildUseCase(String username) throws NullPointerException {
if (username == null) {
throw new NullPointerException("Query must not be null");
}
return getGitHubService().searchUser(username);
}
For me it worked out to add a Observable.Transformer<T, T> as followed:
void gatherData() {
service.doSomeMagic()
.compose(getSchedulerTransformer())
.subscribe(view::displayValue);
}
private <T> Observable.Transformer<T, T> getSchedulerTransformer() {
if (mTransformer == null) {
mTransformer = (Observable.Transformer<T, T>) observable -> observable.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
}
return mTransformer;
}
void setSchedulerTransformer(Observable.Transformer<Observable<?>, Observable<?>> transformer) {
mTransformer = transformer;
}
And to set the Transformer. I just passed this:
setSchedulerTransformer(observable -> {
if (observable instanceof Observable) {
Observable observable1 = (Observable) observable;
return observable1.subscribeOn(Schedulers.immediate())
.observeOn(Schedulers.immediate());
}
return null;
});
So just add a #Before method in your test and call presenter.setSchedulerTransformer and it should be able to test this. If you want more detail check this answer.
If you are using Mockito, you can probably get hold of a SearchUserSubscriber using an ArgumentCaptor, for example...
#Captor
private ArgumentCaptor<SearchUserSubscriber> subscriberCaptor;
private SearchUserSubscriber getSearchUserSubscriber() {
// TODO: ...set up the view model...
...
// Execute the code under test (making sure the line 'searchUserUseCase.execute(new SearchUserSubscriber(), username);' gets hit...)
viewModel.onClickSearch(view);
verify(searchUserUseCase).execute(subscriberCaptor.capture(), any(String.class));
return subscriberCaptor.getValue();
}
Now you can have test cases such as...
#Test
public void shouldDoSomethingWithTheSubscriber() {
SearchUserSubscriber subscriber = getSearchUserSubscriber();
...
}

retrofit with rxjava handling network exceptions globally

I am trying to handle exceptions in app on global level, so that retrofit throws an error i catch it in some specific class with logic for handling those errors.
I have an interface
#POST("/token")
AuthToken refreshToken(#Field("grant_type") String grantType, #Field("refresh_token") String refreshToken);
and observables
/**
* Refreshes auth token
*
* #param refreshToken
* #return
*/
public Observable<AuthToken> refreshToken(String refreshToken) {
return Observable.create((Subscriber<? super AuthToken> subscriber) -> {
try {
subscriber.onNext(apiManager.refreshToken(REFRESH_TOKEN, refreshToken));
subscriber.onCompleted();
} catch (Exception e) {
subscriber.onError(e);
}
}).subscribeOn(Schedulers.io());
}
When i get 401 from server (invalid token or some other network related error) i want to refresh the token and repeat the rest call. Is there a way to do this with rxjava for all rest calls with some kind of observable that will catch this error globally, handle it and repeat the call that throw-ed it?
For now i am using subject to catch the error on .subscribe() like this
private static BehaviorSubject errorEvent = BehaviorSubject.create();
public static BehaviorSubject<RetrofitError> getErrorEvent() {
return errorEvent;
}
and in some call
getCurrentUser = userApi.getCurrentUser().observeOn(AndroidSchedulers.mainThread())
.subscribe(
(user) -> {
this.user = user;
},
errorEvent::onNext
);
then in my main activity i subscribe to that behaviour subject and parse the error
SomeApi.getErrorEvent().subscribe(
(e) -> {
//parse the error
}
);
but i cant repeat the call for the observable that throw the error.
You need to use the operator onErrorResumeNext(Func1 resumeFunction), better explained in the official wiki:
The onErrorResumeNext( ) method returns an Observable that mirrors the behavior of the source Observable, unless that Observable invokes onError( ) in which case, rather than propagating that error to the Subscriber, onErrorResumeNext( ) will instead begin mirroring a second, backup Observable
In your case I would put something like this:
getCurrentUser = userApi.getCurrentUser()
.onErrorResumeNext(refreshTokenAndRetry(userApi.getCurrentUser()))
.observeOn(AndroidSchedulers.mainThread())
.subscribe(...)
where:
private <T> Func1<Throwable,? extends Observable<? extends T>> refreshTokenAndRetry(final Observable<T> toBeResumed) {
return new Func1<Throwable, Observable<? extends T>>() {
#Override
public Observable<? extends T> call(Throwable throwable) {
// Here check if the error thrown really is a 401
if (isHttp401Error(throwable)) {
return refreshToken().flatMap(new Func1<AuthToken, Observable<? extends T>>() {
#Override
public Observable<? extends T> call(AuthToken token) {
return toBeResumed;
}
});
}
// re-throw this error because it's not recoverable from here
return Observable.error(throwable);
}
};
}
Note also that this function can be easily used in other cases, because it's not typed with the actual values emitted by the resumed Observable.
#Override
public Observable<List<MessageEntity>> messages(String accountId, int messageType) {
return mMessageService.getLikeMessages(messageType)
.onErrorResumeNext(mTokenTrick.
refreshTokenAndRetry(mMessageService.getLikeMessages(messageType)));
}

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