painless-dagger-mainfragmenttest.kt

@RunWith(AndroidJUnit4::class)
class MainFragmentTest {
​
    @MockK
    private lateinit var fakeViewModel: MainFragmentViewModel
​
    @Before
    fun setUp() = MockKAnnotations.init(this)
​
    @Test
    fun `testFragmentUpdateData`() {
        // mock the viewmodel behavior
        every { fakeViewModel.isLoading() } returns MutableLiveData(false)
        every { fakeViewModel.getData() } returns MutableLiveData("Hello World from Mock")
​
        // use androidx.test to launch fragment in isolation and inject in mocked ViewModel
        launchFragmentInContainer<MainFragment>(
            Bundle.EMPTY,
            R.style.FragmentScenarioEmptyFragmentActivityTheme,
            FragFactoryFake(fakeViewModel)
        )
​
        // verify results
        onView(withId(R.id.loadingView))
            .check(matches(withEffectiveVisibility(Visibility.GONE)))
        onView(withId(R.id.textView))
            .check(matches(withText("Hello World from Mock")))
    }
}