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

I haven't already used IdilingResources in Espresso, but did you saw these articles:

• Espresso: Custom Idling Resource by Chiuki
• Wait for it...a deep dive into Espresso's Idling Resources

Also please check official Android Docs: Idling Resources (reference)

To answer your question,

• the best way to do it is passing in an instance of one of the Views into the class's constructor. Check: Calling findViewById() from outside an activity

• another way is getting view by context. Check android - How to get view from context?

Here's an exmple taken from a link above:

Starting with a context, the root view of the associated activity can be had by

View rootView = ((Activity)_context).Window.DecorView.FindViewById(Android.Resource.Id.Content);

In Raw Android it'd look something like:

View rootView = ((Activity)mContext).getWindow().getDecorView().findViewById(android.R.id.content)

Then simply call the findViewById on this

View v = rootView.findViewById(R.id.your_view_id);

This might be also useful: How to call getResources() from a class which has no context?

Hope it help

Answer 2

Figured it out. To get the view to pass into an idling resource, all you have to do is take the member variable of your ActivityTestRule

For example:

@Rule
public ActivityTestRule<MainActivity> activityTestRule = new ActivityTestRule<>(
        MainActivity.class);

and then just call getActivity().findViewById(R.id.viewId)

So the end result is:

activityTestRule.getActivity().findViewById(R.id.viewId);

Answer 3

If you are using ActivityScenarioRule from androidx.test.ext.junit.rules (since ActivityTestRule "will be deprecated and eventually removed from library in the future"), you can get your Activity instance and call findViewById method:

import androidx.test.ext.junit.rules.activityScenarioRule
import androidx.test.ext.junit.runners.AndroidJUnit4

@RunWith(AndroidJUnit4::class) {

    @get: Rule
    var testRule = activityScenarioRule<MainActivity>()

    @Test
    fun mainTestCase() {
        testRule.scenario.onActivity { activity ->
            val view = activity.findViewById<YourView>(R.id.view)
        }
    }
}

Answer 4

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<Activity> 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);
}