将活动放回前台时，startActivitySync会挂起

Question

I am writing a test that launches my main activity and, right after that, I put it into background by launching the home screen by using the following intent:

    Intent intent= new Intent(Intent.ACTION_MAIN);
    intent.addCategory(Intent.CATEGORY_HOME);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

After that, I try to put my app's activity back into foreground by using an intent similar to the one above (it doesn't have the CATEGORY_HOME flag and, instead, I am adding the activity's name and package). Since I need to make sure my app's activity was successfully launched, I am using the "startActivitySync" method from Instrumentation.

When I run the test I see that the app is being successfully put into background and then back to foreground, but the test run never finishes. It hangs forever in the "startActivitySync" method. Any ideas of why this is happening?

Answer 1

In my experience:

public testOne(){
 MyActivity first = startActivitySync(...);
 first.finish();
 MyActivity second = startActivitySync(...);
}

public testTwo(){
 MyActivity first = startActivitySync(...);
 ...
}

, testOne() will succeed,
but testTwo() will hang on "startActivitySync".

Suggested fix:
Cleanup your started activities at the end of every test, ex:

public testOne(){
 MyActivity first = startActivitySync(...);
 first.finish();
 MyActivity second = startActivitySync(...);
 second.finish();
}

public testTwo(){
 MyActivity first = startActivitySync(...);
 first.finish();
}

Answer 2

There're lots of such questions but almost all answerers suggest to finish an activity which I suppose in most cases does not work.

If your activity doesn't finish it just means that some UI operation continues to run. And actually it could mean that something wrong with your activity. For instance recently I faced similar problem and found out that an animation was not appropriately stopped:

Animation anim = AnimationUtils.loadAnimation(getContext(), R.anim.rotate_infinite_clockwise);
view.startAnimation(anim);

So the most straight forward method of solving the problem is disabling views one by one.

Answer 3

Instead of using this constructor:

Intent intent = new Intent(String action);

try this one:

Intent intent = new Intent(Context packageContext, Class<?> cls):

I ran into a similar issue with startActivitySync(Intent) hanging, and this resolved it for me. It worked fine on the first test but failed on subsequent tests in the same class. Why? I don't know.