MainActivityTest.java

@LargeTest
@RunWith(AndroidJUnit4.class)
public class MainActivityTest {

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

    @Test
    public void mainActivityTest() {

        ViewInteraction textView = onView(allOf(withId(R.id.textview),
                withText("Hello World")));
        textView.check(matches(withText("Hello World")));

        ViewInteraction appCompatButton = onView(
                allOf(withId(R.id.button), withText("Click"), isDisplayed()));
        appCompatButton.perform(click());
        try {
            Thread.sleep(300);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        ViewInteraction textView2 = onView(allOf(withId(R.id.textview),
                withText("Bye World")));
        textView.check(matches(withText("Bye World")));

    }
}