Mock ViewModel in Activity for UI Testing with Espresso

I’m try to setup UI testing similar GithubBrowserSample and look like sample project have only mock ViewModel for Fragment but for Activity it doesn’t.

So, on my code activityRule.activity.viewModelFactory = createViewModelFor(viewModel) it doesn’t set before onCreate() in Activity, meant it doesn’t use mock ViewModel.

class MainActivityTest {

    val viewModel = mock(MainViewModel::class.java)

    @Rule
    @JvmField
    val activityRule = ActivityTestRule<MainActivity>(MainActivity::class.java, true, true)

    private val liveData = MutableLiveData<Resource<Object>>()

    @Before
    open fun setUp() {
        activityRule.activity.viewModelFactory = createViewModelFor(viewModel)
        `when`(viewModel.liveData).thenReturn(liveData)
        viewModel.liveData?.observeForever(mock(Observer::class.java) as Observer<Resource<Object>>)
        liveData.postValue(Resource.success(Object()))
    }

    fun <T : ViewModel> createViewModelFor(model: T): ViewModelProvider.Factory =
        object : ViewModelProvider.Factory {
            override fun <T : ViewModel> create(modelClass: Class<T>): T {
                if (modelClass.isAssignableFrom(model.javaClass)) {
                    return model as T
                }
                throw IllegalArgumentException("unexpected model class " + modelClass)
            }
        }
}

Can someone help me about this issue please?

[kekefigure]

Use the following class to create the activity instance: https://developer.android.com/reference/android/support/test/runner/intercepting/SingleActivityFactory.html Then you can create different factories for mocked/injected activities. Example with dagger2 injection:

private SingleActivityFactory<MainActivity> injectedFactory = new SingleActivityFactory<MainActivity>(MainActivity.class) {
        @Override
        protected MainActivity create(Intent intent) {
            MainActivity activity = new MainActivity();
            activity.viewModelFactory = testApp.daggerTestAppComponent.vmFactory();
            return activity;
        }
 };

@Rule
public ActivityTestRule<MainActivity> mActivityTestRule = new ActivityTestRule<>(injectedFactory, false, false);

[aumarbello]

@danielwilson1702 Can you please post your final working code? I’m currently trying to mock an activity’s viewmodel and haven’t been able to achieve it.