我在我的 Android 单元测试中尝试使用 MockWebServer + Retrofit + Coroutines 失败。在调试过程中,我发现 OkHttp 在不同的线程上运行,这就是为什么我的测试总是失败。
这是我设置测试调度程序的规则:
class MainCoroutineRule(
private val scheduler: TestCoroutineScheduler = TestCoroutineScheduler(),
val testDispatcher: TestDispatcher = UnconfinedTestDispatcher(scheduler)
) : TestWatcher() {
val testScope = TestScope(testDispatcher)
override fun starting(description: Description) {
super.starting(description)
Dispatchers.setMain(testDispatcher)
}
override fun finished(description: Description) {
super.finished(description)
Dispatchers.resetMain()
}
}
这是我的 View 模型:
@HiltViewModel
class TestViewModel @Inject constructor(
private val repository: TestRepository,
@MainDispatcher private val dispatcher: CoroutineDispatcher
) : ViewModel() {
val hasData = MutableLiveData(false)
fun fetchSomething() {
viewModelScope.launch(dispatcher) {
when (repository.getSomething()) {
is Success -> {
hasData.value = true
}
else -> {
hasData.value = false
}
}
}
}
}
最后是测试:
class TestViewModelTest : MockServerSuite() {
@get:Rule
val taskExecutorRule = InstantTaskExecutorRule()
@get:Rule
val mainTestRule = MainCoroutineRule()
@Test
fun `my test`() = mainTestRule.testScope.runTest {
// setting up MockWebServer
val viewModel = TestViewModel(
repository = TestRepository(
api = testApi(server),
),
dispatcher = mainTestRule.testDispatcher
)
viewModel.fetchSomething()
assertThat(viewModel.hasData.value).isTrue
}
}
由于 Retrofit 是主安全的,我不知道如何让它在我的 testDispatcher 上运行。我错过了什么吗?
正如 Petrus 提到的,我已经使用了 getOrAwaitValue
,它适用于简单的场景。
在我们的大多数用例中,我们的请求在收到一些数据后会触发其他请求。
通常,我收到 getOrAwaitValue 的中间值,而不是我期望的最终 LiveData。
最佳答案
尝试使用 getOrAwaitValue
:)
class TestViewModelTest {
@Test
fun `my test`() = mainTestRule.testScope.runTest {
// setting up MockWebServer
val viewModel = TestViewModel(
repository = TestRepository(
api = testApi(server),
),
dispatcher = mainTestRule.testDispatcher
)
viewModel.fetchSomething()
assertThat(viewModel.hasData.getOrAwaitValue()).isTrue
}
}
@VisibleForTesting(otherwise = VisibleForTesting.NONE)
fun <T> LiveData<T>.getOrAwaitValue(
time: Long = 2,
timeUnit: TimeUnit = TimeUnit.SECONDS,
afterObserve: () -> Unit = {}
): T {
var data: T? = null
val latch = CountDownLatch(1)
val observer = object : Observer<T> {
override fun onChanged(o: T?) {
data = o
latch.countDown()
this@getOrAwaitValue.removeObserver(this)
}
}
this.observeForever(observer)
try {
afterObserve.invoke()
// Don't wait indefinitely if the LiveData is not set.
if (!latch.await(time, timeUnit)) {
throw TimeoutException("LiveData value was never set.")
}
} finally {
this.removeObserver(observer)
}
@Suppress("UNCHECKED_CAST")
return data as T
}
关于android - 如何让 MockWebServer + Retrofit + Coroutines 在同一个调度器中运行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/71489875/