如何使用 Koin 对 MVVM 进行单元测试？

Question

如何使用 Koin 对 MVVM 进行单元测试？

我正在尝试测试：link

但是，我不知道为什么我在 ViewModelTest 中得到error("No Data in ViewModel") fun getLookUpLeagueList()

存储库

class LookUpLeagueRepository {

    fun getLookUpLeague(idLeague: String): MutableLiveData<LookUpLeague> {
        val lookUpLeague = MutableLiveData<LookUpLeague>()
        APIService().getLookUpLeague(idLeague).enqueue(object : Callback<LookUpLeague> {
            override fun onFailure(call: Call<LookUpLeague>, t: Throwable) {
                d("TAG", "lookUpLeagueOnFailure ${t.localizedMessage}")
            }

            override fun onResponse(call: Call<LookUpLeague>, response: Response<LookUpLeague>) {
                lookUpLeague.value = response.body()
            }
        })
        return lookUpLeague
    }
}

视图模型

class LookUpLeagueViewModel(private val lookUpLeagueRepository: LookUpLeagueRepository) :
    ViewModel() {

    var lookUpLeagueList = MutableLiveData<LookUpLeague>()

    fun getLookUpLeagueList(idLeague: String) {
        lookUpLeagueList = lookUpLeagueRepository.getLookUpLeague(idLeague)
    }
}

模块

val lookUpLeagueModule = module {
    single { LookUpLeagueRepository() }
    viewModel { LookUpLeagueViewModel(get()) }
}

ViewModel 测试

class LookUpLeagueViewModelTest : KoinTest {

    val lookUpLeagueViewModel: LookUpLeagueViewModel by inject()

    val idLeague = "4328"

    @get:Rule
    val rule = InstantTaskExecutorRule()

    @Mock
    lateinit var observerData: Observer<LookUpLeague>

    @Before
    fun before() {
        MockitoAnnotations.initMocks(this)
        startKoin {
            modules(lookUpLeagueModule)
        }
    }

    @After
    fun after() {
        stopKoin()
    }

    @Test
    fun getLookUpLeagueList() {
        lookUpLeagueViewModel.lookUpLeagueList.observeForever(observerData)

        lookUpLeagueViewModel.getLookUpLeagueList(idLeague)

        val value = lookUpLeagueViewModel.lookUpLeagueList.value ?: error("No Data in ViewModel")

        Mockito.verify(observerData).onChanged(value)
    }
}

Answer 1

@Test
fun getLookUpLeagueList() {
    lookUpLeagueViewModel.lookUpLeagueList.observeForever(observerData)
    ...
}

此时lookUpLeagueList 是MutableLiveData 的一个实例。说这是MutableLiveData #1。

lookUpLeagueViewModel.getLookUpLeagueList(idLeague)

执行上面的代码会调用LookUpLeagueViewModel.getLookUpLeagueList 函数。让我们来看看它的内部。

lookUpLeagueList = lookUpLeagueRepository.getLookUpLeague(idLeague)

在LookUpLeagueRepository 内部创建了一个全新的MutableLiveData。这与observerData 正在观察的不同。此时lookUpLeagueViewModel.lookUpLeagueList指的是新的MutableLiveData #2，因为你重新分配给var lookUpLeagueList。

val value = lookUpLeagueViewModel.lookUpLeagueList.value ?: error("No Data in ViewModel")

因此，您实际上是在查询MutableLiveData #2，它是新的、未观察到的并且是空的。这就是为什么value 是null。与其声明为var，不如声明为val。不要重新分配变量 setValue 或 postValue 来传播更改。