Espresso: How do i assert if a particular activity is launched when i click on a item using espresso

Issue

How do I assert an activity in Espresso after I click on a view item?

onView(withId(com.example.android.notepad.R.id.XYZ)).perform(click());

Solution

You should simulate the process of clicking a button and then test if the activity at the top of the stack is the one you're looking for

@RunWith(AndroidJUnit4.class)
public class YourTestClass{


    @Test
    public void testButton() {
        Espresso.onView(ViewMatchers.withId(R.id.yourButtonId)).perform(ViewActions.click());

        Assert.assertEquals(getActivityInstance().getClass(), YourActivityThatShouldStart.class);
    }

    private Activity getActivityInstance() {
        final Activity[] currentActivity = {null};
        InstrumentationRegistry.getInstrumentation().runOnMainSync(new Runnable() {
            public void run() {
                Collection resumedActivities = ActivityLifecycleMonitorRegistry.getInstance().getActivitiesInStage(Stage.RESUMED);
                if (resumedActivities.iterator().hasNext()) {
                    currentActivity[0] = (Activity) resumedActivities.iterator().next();
                }
            }
        });

        return currentActivity[0];
    }

}

On the testButton function, there are two lines, the first one to click on your button, the second one is to check the resulting activity

Espresso works on the main thread so your fine

Answered By - William Kinaan