IdlingResource Espresso with RxJava

Question

I recently converted my application from using async tasks to rxjava. Now, my espresso tests no longer wait for my data calls to complete due to espresso not having an idling r

Answer 1

Here is how I solved the problem:

IdlingResource implementation:

public class IdlingApiServiceWrapper implements MyRestService, IdlingResource {

private final MyRestService           api;
private final AtomicInteger counter;
private final List<ResourceCallback> callbacks;

public IdlingApiServiceWrapper(MyRestService api) {
    this.api = api;
    this.callbacks = new ArrayList<>();
    this.counter = new AtomicInteger(0);
}

public Observable<MyData> loadData(){
    counter.incrementAndGet();
    return api.loadData().finallyDo(new Action0() {
        @Override
        public void call() {
            new Handler(Looper.getMainLooper()).post(new Runnable() {
                @Override
                public void run() {
                    counter.decrementAndGet();
                    notifyIdle();
                }
            });
        }
    });
}

@Override public String getName() {
    return this.getClass().getName();
}

@Override public boolean isIdleNow() {
    return counter.get() == 0;
}

@Override public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
    callbacks.add(resourceCallback);
}

private void notifyIdle() {
    if (counter.get() == 0) {
        for (ResourceCallback cb : callbacks) {
            cb.onTransitionToIdle();
        }
    }
   }
   }

and here is my test:

public class MyActivityTest extends ActivityInstrumentationTestCase2<MyActivity> {
@Inject
IdlingApiServiceWrapper idlingApiWrapper;

@Override
public void setUp() throws Exception {
    //object graph creation

    super.setUp();
    getActivity();
    Espresso.registerIdlingResources(idlingApiWrapper);
}

public void testClickOpenFirstSavedOffer() throws Exception {
    onData(is(instanceOf(DataItem.class)))
            .atPosition(0)
            .perform(click());
   }
  }

I used Dagger for dependency injection.

Answer 2

Wrote a little integration piece between RxJava Plugins and Espresso. Hope this helps someone else.

https://gist.github.com/digitalbuddha/d886eae1578bca78b9bf

Edit:

There is a much easier way to accomplish this task. Add the following rule to your tests

public class AsyncTaskSchedulerRule implements TestRule {
    final Scheduler asyncTaskScheduler = Schedulers.from(AsyncTask.THREAD_POOL_EXECUTOR);

    @Override
    public Statement apply(Statement base, Description description) {
        return new Statement() {
            @Override
            public void evaluate() throws Throwable {
                RxJavaHooks.setOnIOScheduler(scheduler -> asyncTaskScheduler);
                RxJavaHooks.setOnComputationScheduler(scheduler -> asyncTaskScheduler);
                RxJavaHooks.setOnNewThreadScheduler(scheduler -> asyncTaskScheduler);
                try {
                    base.evaluate();
                } finally {
                    RxJavaHooks.reset();
                }
            }
        };
    }
}

Answer 3

I am currently using this implementation. Its easier and works very well for me so far: https://github.com/rosshambrick/RxEspresso