MainViewModel extends ViewModel { public void onClickButtonClicks() { attachedActivity.startActivity(ClickCountActivity.class); } MainViewModel(@NonNull ActivityComponent activityComponent,
                  @Nullable State savedInstanceState); void onClickButtonClicks(); void onClickButtonRecyclerView(); void onClickHiBrianLee();  }
@Test public void testOnClickButtonClicks() { viewModel.onClickButtonClicks(); verify(attachedActivity).startActivity(ClickCountActivity.class); }