AsyncTask.onPostExecute() never gets called in ServiceTestCase

Question

I am writing a unit test for a service using ServiceTestCase.

The service basically executes an AsyncTask that does some work and then does something else in onPostExecute().

The service works as expected when I run and debug it in a (virtual) device.

But in the test extending ServiceTestCase, I only get into doInBackground(). Once the methods returns, onPostExecute() never gets called. I am letting the test sleep() so the AsyncTask has time to complete its work.

This is the simplified service:

public class ServiceToTest extends Service {
    private AtomicBoolean busy = new AtomicBoolean(false);

    @Override
    public IBinder onBind(final Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(final Intent intent, final int flags,
        final int startId) {
        this.handleCommand();
        return START_NOT_STICKY;
    }

    /**
    * Workaround for http://code.google.com/p/android/issues/detail?id=12117
    */
    @Override
    public void onStart(final Intent intent, final int startId) {
        this.handleCommand();
    }

    public void handleCommand() {
        new TaskToTest().execute();
    }

    public boolean isBusy() {
        return busy.get();
    }

    private class TaskToTest extends AsyncTask<Boolean, Void, TestInfo> {
        @Override
        protected void onPreExecute() {
            busy.set(true);
        }

        @Override
        protected TestInfo doInBackground(final Boolean... args) {
            return null;
        }

        @Override
        protected void onPostExecute(final TestInfo info) {
            busy.set(false);
        }
    }
}

An this is the test for it:

public class ServiceTest extends ServiceTestCase<ServiceToTest> {
    public ServiceTest() {
        super(ServiceToTest.class);
    }

    public void testIsBusy() throws InterruptedException {
        startService(new Intent("this.is.the.ServiceToTest"));  
        ServiceToTest serviceToTest = this.getService();
        assertTrue(serviceToTest.isBusy());
        Thread.sleep(10000);
        assertFalse(serviceToTest.isBusy());
    }
}

I suppose that the environment provided by ServiceTestCase is somewhat limited so this doesn't work, but is there anything I can do to make it work anyway?

Cheers, Torsten

Answer 1

The problem is that your background thread is waiting for the UI to be "alive", you need to call Looper.prepare() and Looper.loop(). It's better explained in this page.

Answer 2

So just to follow up on how I got it to work with the info provided by dmon.

I changed my test to the below:

public class ServiceTest extends ServiceTestCase {

public ServiceTest() {
    super(ServiceToTest.class);
}

public void testIsBusy() throws InterruptedException {

    // Starts the service and asserts that onPreExecute() was called
    ServiceTestThread serviceTestThread = new ServiceTestThread();
    serviceTestThread.start();

    // Wait for the service to start and complete doInBackground()
    // TODO Implement something smarter than this...
    Thread.sleep(1000);

    // Assert that onPostExecute() was called
    assertFalse(serviceTestThread.serviceToTest.isBusy());

}

private class ServiceTestThread extends Thread {

    ServiceToTest serviceToTest;

    public void run() {
        Looper.prepare();

        startService(new Intent("this.is.the.ServiceToTest"));

        serviceToTest = getService();

        assertTrue(serviceToTest.isBusy());

        Looper.loop();
    }

}

}

I'll see now to make this ServiceTestThread more generic so it can be reused.

Torsten

Answer 3

Not sure if this is useful to anybody else, but this was my attempt at abstracting Tortens answer and making it more reusable.

    private synchronized boolean getWaitFlag()
    {
        return _waitFlag;
    }

    private boolean _waitFlag;

    private synchronized void setWaitFlag(boolean value)
    {
        _waitFlag = value;
    }

    private void waitForCompletionFlag() throws InterruptedException
    {
        Calendar cal = Calendar.getInstance();
        while (getWaitFlag() == false)
        {
            Thread.sleep(10);
            if (Calendar.getInstance().getTimeInMillis() - cal.getTimeInMillis() > 1000) // Wait at most 1 second
            {
                Log.e("timeout", "timed out waiting to complete task");
                break;
            }
        }
    }

private abstract class EmulatedUI extends Thread
    {
        public abstract void doWork();

        public void run()
        {
            Looper.prepare();
            doWork();
            Looper.loop();
        }
    }

public void testSomething() throws InterruptedException
{
    EmulatedUI thread = new EmulatedUI() {

        @Override
        public void doWork()
        {
            _objectToTest.someAsyncCall(new WorkCompletedCallback() {

                        @Override
                        public void onComplete()
                        {
                                   // could possibly assert things here
                            setWaitFlag(true);
                        }
                    });

        }
    };
    thread.start();
    waitForCompletionFlag();
    // assert things here since you know the async task has completed.
}

Answer 4

I had the same problem when attempting to bind to a service from the test runner thread, rather than the ui thread. Try calling startService from the ui thread.

public void testIsBusy() throws Exception {
  final CountDownLatch latch = new CountDownLatch(1);

  new Handler(Looper.getMainLooper()).post(new Runnable() {
    @Override
    public void run() {
      startService(new Intent("this.is.the.ServiceToTest"));  
      ServiceToTest serviceToTest = this.getService();
      assertTrue(serviceToTest.isBusy());
      Thread.sleep(10000);
      assertFalse(serviceToTest.isBusy());
      latch.countDown();
    }
  });

  latch.await(5, TimeUnit.SECONDS);
}