android - MediatorLiveData源在测试期间不会更新

Question

我的 View 模型中有一个MediatorLiveData，应该对模型层的LiveData发射使用react，并在必要时采取措施并更新其侦听器。由于某些原因，源在测试期间不会更新。

class MyViewModel(private val repository: Repository) : ViewModel() {
    private val liveData1: LiveData<String> = repository.getString1()
    private val livedata2: LiveData<String> = repository.getString2()

    val currentState = MediatorLiveData<MyState>

    init {
        currentState.addSource(liveData1) {
            it?.let { string1 ->
                doSomething()
                currentState.postValue(String1Updated)
            }
        }
        currentState.addSource(liveData2) {
            it?.let { string1 ->
                doSomethingElse()
                currentState.postValue(String2Updated)
            }
        }
    }
}

模拟观察者和存储库方法似乎无济于事。永远不会调用doSomething()，并且currentState不会更新为String1Updated。

@RunWith(MockitoJUnitRunner::class)
class MyViewModelTest {
    @get:Rule instantTaskExecutorRule = InstantTaskExecutorRule()

    @Mock lateinit var mockRepository: Repository

    @Mock lateinit var mockLiveData1: MutableLiveData<String>

    @Mock lateinit var mockLiveData2: MutableLiveData<String>

    @Mock lateinit var mockStateObserver: Observer<MyState>

    lateinit var myViewModel: MyViewModel

    @Before
    fun setup() {
        whenever(mockRepository.getLiveData1()).thenReturn(mockLiveData1)
        whenever(mockRepository.getLiveData2()).thenReturn(mockLiveData2)

        myViewModel = myViewModel(mockRepository)
    }

    @Test
    fun `Does something when live data 1 is updated`() {
        myViewModel.state.observeForever(mockStateObserver)
        mockLiveData1.postValue("hello world")

        verify(mockStateObserver).onChanged(String1Updated)
    }
}

即使将观察者除了直接放在调解器上的mockLiveData1和mockLiveData2上，也不会导致在调解器中更新源。

Answer 1

如我的帖子中所示，我正在使用模拟LiveData作为调解器数据的源。这些应该只是LiveData实现。

@Before
fun setup() {
    liveData1 = MutableLiveData()
    whenever(mockRepository.getLiveData1()).thenReturn(liveData1)
    liveData1.postValue("initial value")
    myViewModel.state.observeForever(mockStateObserver)
}