Inject ViewModelFactory.Provider in activity for espresso testing

Question

Related to this question: Espresso, Dagger2 set ViemodelProvider.Factory on BaseActivity

I went through hell and back to get a ViewModelFactory.Provider on an Activity during my tests, in order to get espresso tests working regarding Android Architecture Components. I expected it to be simple, but I guess it's not...

The example to get it working with fragments is straightforward:
https://github.com/googlesamples/android-architecture-components/blob/master/GithubBrowserSample/app/src/androidTest/java/com/android/example/github/ui/user/UserFragmentTest.java

@Before
public void init() {
    UserFragment fragment = UserFragment.create("foo");
    viewModel = mock(UserViewModel.class);
    when(viewModel.getUser()).thenReturn(userData);
    when(viewModel.getRepositories()).thenReturn(repoListData);
    navigationController = mock(NavigationController.class);
    fragmentBindingAdapters = mock(FragmentBindingAdapters.class);

    fragment.viewModelFactory = ViewModelUtil.createFor(viewModel);
    fragment.navigationController = navigationController;
    fragment.dataBindingComponent = () -> fragmentBindingAdapters;

    activityRule.getActivity().setFragment(fragment);
}

However, this simply won't work with activities as I can't get the dependencies on the activity before its creation using an ActivityTestRule.
I followed the same new dependency injection flow with Dagger2 as in the example above using the HasActivityInjector interface.

I would appreciate your help!

Answer 1

It’s possible to set injected activity attribute by registering a custom ActivityLifecycleCallbacks in your TestApp in the @Before Method.

Example:

 @Before
public void init(){


    UserFragment fragment = UserFragment.create("foo");
    viewModel = mock(UserViewModel.class);
    when(viewModel.getUser()).thenReturn(userData);
    when(viewModel.getRepositories()).thenReturn(repoListData);
    navigationController = mock(NavigationController.class);


    TestApp testApp = ((TestApp) InstrumentationRegistry.getContext().getApplicationContext());
    testApp.registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {
        @Override
        public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
            //will be called before the onCreate method of your activity
            activity.setViewModelFactory(ViewModelUtil.createFor(viewModel));
        }

        @Override
        public void onActivityStarted(Activity activity) {

        }

        @Override
        public void onActivityResumed(Activity activity) {

        }

        @Override
        public void onActivityPaused(Activity activity) {

        }

        @Override
        public void onActivityStopped(Activity activity) {

        }

        @Override
        public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

        }

        @Override
        public void onActivityDestroyed(Activity activity) {

        }
    });


    fragment.viewModelFactory = ViewModelUtil.createFor(viewModel);
    fragment.navigationController = navigationController;
    fragment.dataBindingComponent = () -> fragmentBindingAdapters;

    activityRule.getActivity().setFragment(fragment);


}