如何在 Kotlin 中使用 ViewModel 测试协程？

我无法测试我的方法，感觉它没有到达 uiScope.launch 块内部，并且我已经发布了我正在尝试测试的 viewModel 方法，并且fetchActivationCodeWithDuration是挂起功能。底部是我的测试类

我收到这条消息

java.lang.AssertionError: 
    Expected :ActivationCode(code=111111, expires=2019-05-23T10:03:50.614Z, duration=815960) Actual   :null

protected val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)

fun loadActivationCode() {
    uiScope.launch {
        progressMessageMutableData.postValue(true)
        when (val result = activationCodeRepository.fetchActivationCodeWithDuration()) {
            is Resource.Success<ActivationCode> -> {
                progressMessageMutableData.postValue(false)
                activationMutableData.postValue(result.data)
            }
            is Resource.Failure -> {
                progressMessageMutableData.postValue(false)
                errorMessageMutableData.postValue(result.message)
            }
        }
    }

suspend fun fetchActivationCodeWithDuration(): Resource<ActivationCode> {}

这是我的测试课

@ExperimentalCoroutinesApi
@RunWith(JUnit4::class)
class ActivationViewModelTest {
    @get:Rule
    val instantTaskExecutorRule = InstantTaskExecutorRule()

    @UseExperimental(ObsoleteCoroutinesApi::class)
    private val mainThreadSurrogate = newSingleThreadContext("UI thread")
    private lateinit var viewModel: ActivationViewModel
    private lateinit var serverTimeFetcher: IServerTimeFetcher
    private lateinit var activationCodeRepository: ActivationRepositoryCode

    @Before
    fun setup() {
        viewModel = ActivationViewModel()
        Dispatchers.setMain(mainThreadSurrogate)
        activationCodeRepository = mock(ActivationRepositoryCode::class.java)
        viewModel.activationCodeRepository = activationCodeRepository
    }

    @After
    fun tearDown() {
        Dispatchers.resetMain() // reset main dispatcher to the original Main dispatcher
        mainThreadSurrogate.close()
    }

    @Test
    fun whenSuccessMenuLoad_loadActivationCode() {
        runBlockingTest {
            Mockito.`when`(activationCodeRepository.fetchActivationCodeWithDuration()).
              thenReturn(Resource.Success(ActivationCode(code = "111111", expires = "2019-05-23T10:03:50.614Z", duration = 815960L)))
            viewModel.loadActivationCode()
            val expected = ActivationCode(code = "111111", expires = "2019-05-23T10:03:50.614Z", duration = 815960L)
            val actual = viewModel.activationData.value
            Assert.assertEquals(expected, actual)
        }
    }
}

更好的方法是将 coroutineDispatcher 传递给 viewModel，这样您就可以在测试中传递测试调度程序。所以你应该有：

class ActivationViewModel(val dispatcher:CoroutineDispatcher){}

在您的测试中，您可以像这样初始化 viewModel ：

val dispatcher=Dispatchers.Unconfined
val viewModelInTest=ActivationViewModel(dispatcher)

问题将会得到解决..