How to get a view from within Espresso to pass into an IdlingResource?

Question

I essentially have a custom IdlingResource that takes a View a constructor argument. I can\'t find anywhere that really talks about how to implemen

Answer 1

The accepted answer works as long as a test is running in the same activity. However, if the test navigates to another activity activityTestRule.getActivity() will return the wrong activity (the first one). To address this, one can create a helper method returning an actual activity:

public Activity getCurrentActivity() {
    final Activity[] currentActivity = new Activity[1];
    InstrumentationRegistry.getInstrumentation().runOnMainSync(new Runnable() {
        @Override
        public void run() {
            Collection allActivities = ActivityLifecycleMonitorRegistry.getInstance()
                    .getActivitiesInStage(Stage.RESUMED);
            if (!allActivities.isEmpty()) {
                currentActivity[0] = allActivities.iterator().next();
            }
        }
    });
    return currentActivity[0];
}

And then it could be used as the following:

Activity currentActivity = getCurrentActivity();
if (currentActivity != null) {
    currentActivity.findViewById(R.id.viewId);
}