HomeFragmentTest.java

package com.mani.fuellog;

@RunWith(AndroidJUnit4.class)
public class HomeFragmentTest {

    @Mock
    private FuelLogViewModel fuelLogViewModel;

    private MutableLiveData<FuelStat> doubleMutableLiveData = new MutableLiveData<>();


    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);

        when(fuelLogViewModel.getAverageFuelConsumption()).thenReturn(doubleMutableLiveData);


         FragmentScenario.launchInContainer(HomeFragment.class,null,new FragmentFactory(){
            @NonNull
            @Override
            public Fragment instantiate(@NonNull ClassLoader classLoader, @NonNull String className) {
                return HomeFragment.newInstance(ViewModelUtil.createFor(fuelLogViewModel));
            }
        }).moveToState(Lifecycle.State.RESUMED);
    }


    @Test
    public void shouldDisplay_averageConsumptionValue_postedValidDoubleOnMutableLiveData() {
        doubleMutableLiveData.postValue(new FuelStat(4.5d,4.5d,0,0,0));

        onView(withId(R.id.average_consumption_value)).check(matches(withText("4.5")));
        onView(withId(R.id.driving_cost_value)).check(matches(withText("4.5")));
        onView(withId(R.id.total_distance_value)).check(matches(withText("0")));
        onView(withId(R.id.total_amount_value)).check(matches(withText("0")));
        onView(withId(R.id.total_consumption_value)).check(matches(withText("0")));

    }

    @Test
    public void shouldDisplay_averageConsumptionValue_postedNullOnMutableLiveData() {
        doubleMutableLiveData.postValue(null);

        onView(withId(R.id.average_consumption_value)).check(matches(withText("--")));
        onView(withId(R.id.driving_cost_value)).check(matches(withText("--")));
        onView(withId(R.id.total_distance_value)).check(matches(withText("--")));
        onView(withId(R.id.total_amount_value)).check(matches(withText("--")));
        onView(withId(R.id.total_consumption_value)).check(matches(withText("--")));
    }

}