讓掛起函數不返回任何東西

Question

考慮這個類：

class TestViewModel(private val interactor: LoginInteractor) : ViewModel() {

    private val _loading = MutableLiveData<Boolean>().apply { value = false }
    val loading: LiveData<Boolean> = _loading

    fun loginClicked() {
        viewModelScope.launch {
            _loading.value = true
            val isLoggedIn = interactor.login()
            _loading.value = false
        }
    }

}

interface LoginInteractor {
    suspend fun login(): Boolean
}

和測試：

class TestViewModelTest {

    @Rule
    @JvmField
    var rule = InstantTaskExecutorRule()

    @Mock
    private lateinit var interactor: LoginInteractor
    @InjectMocks
    private lateinit var tested: TestViewModel

    @Before
    fun setUp() {
        MockitoAnnotations.initMocks(this)
        Dispatchers.setMain(TestCoroutineDispatcher())
    }

    @Test
    fun `should set loading to true while loading`() = runBlockingTest {
        given(interactor.login()).willReturn(true)

        tested.loginClicked()

        Assert.assertTrue(tested.loading.value!!)
    }
}

當斷言loading值為true ，顯然它實際上不是。

當我們使用 RxJava 時， LoginInteractor看起來像：

interface LoginInteractor {
    fun login(): Single<Boolean>
}

在測試中，我們可以做到

given(interactor.login()).willReturn(Single.never())

測試登錄時ViewModel的狀態； 當loginClicked()被調用但interactor.login()尚未返回時，如何延遲/不返回交互器的任何suspend函數login()以測試ViewModel 的狀態？

Answer 1

選項1：

為了保證你的狀態發生變化，你可以訂閱加載狀態的變化：

@Test
 fun `should set loading to true while loading`() = runBlockingTest {
     given(interactor.login()).willReturn(true)

     var invocationCounter = 0
     tested.loading.observerForever { loading -> 
         assertEquals(invocationCounter == 0, loading)
         invocationCounter++
     }

     tested.loginClicked()

     Assert.assertTrue(tested.loading.value!!)
 }

選項 2：

   ```
     given(interactor.login()).willAnswer {
         assertTrue(tested.loading.value)
         true
    }

    tested.loginClicked()

    Assert.assertFalse(tested.loading.value!!)