基于viewModelScope的Kotlin协同测试流程采集
基于viewModelScope的Kotlin协同测试流程采集
提问于 2019-09-26 10:48:49
我想测试一个收集流的ViewModel方法。在收集器内部，一个LiveData对象会发生变异，我想在最后检查它。这大致是设置的样子：
//Outside viewmodel
val f = flow { emit("Test") }.flowOn(Dispatchers.IO)
//Inside viewmodel
val liveData = MutableLiveData<String>()
fun action() {
viewModelScope.launch { privateAction() }
}
suspend fun privateAction() {
f.collect {
liveData.value = it
}
}现在，当我在单元测试中调用action()方法时，测试在收集流之前就完成了。这就是测试的样子：
@Test
fun example() = runBlockingTest {
viewModel.action()
assertEquals(viewModel.liveData.value, "Test")
}我通过这个TestCoroutineDispatcher扩展使用Junit5，同时也使用LiveData的即时执行器扩展：
class TestCoroutineDispatcherExtension : BeforeEachCallback, AfterEachCallback, ParameterResolver {
@SuppressLint("NewApi") // Only used in unit tests
override fun supportsParameter(parameterContext: ParameterContext?, extensionContext: ExtensionContext?): Boolean {
return parameterContext?.parameter?.type === testDispatcher.javaClass
}
override fun resolveParameter(parameterContext: ParameterContext?, extensionContext: ExtensionContext?): Any {
return testDispatcher
}
private val testDispatcher = TestCoroutineDispatcher()
override fun beforeEach(context: ExtensionContext?) {
Dispatchers.setMain(testDispatcher)
}
override fun afterEach(context: ExtensionContext?) {
Dispatchers.resetMain()
testDispatcher.cleanupTestCoroutines()
}
}
class InstantExecutorExtension : BeforeEachCallback, AfterEachCallback {
override fun beforeEach(context: ExtensionContext?) {
ArchTaskExecutor.getInstance()
.setDelegate(object : TaskExecutor() {
override fun executeOnDiskIO(runnable: Runnable) = runnable.run()
override fun postToMainThread(runnable: Runnable) = runnable.run()
override fun isMainThread(): Boolean = true
})
}
override fun afterEach(context: ExtensionContext?) {
ArchTaskExecutor.getInstance().setDelegate(null)
}
}回答 2
Stack Overflow用户
回答已采纳
发布于 2020-08-18 06:31:48
因此，我最后所做的只是将Dispatcher传递给viewmodel构造函数：
class MyViewModel(..., private val dispatcher = Dispatchers.Main)然后像这样使用它：
viewModelScope.launch(dispatcher) {}现在，当我用一个ViewModel实例化测试中的TestCoroutineDispatcher时，我可以重写它，然后提前时间，使用testCoroutineDispatcher.runBlockingTest {}等等。
Stack Overflow用户
发布于 2019-09-26 12:55:35
你也可以试试，
fun action() = viewModelScope.launch { privateAction() }
suspend fun privateAction() {
f.collect {
liveData.value = it
}
}
@Test
fun example() = runBlockingTest {
viewModel.action().join()
assertEquals(viewModel.liveData.value, "Test")
}或
fun action() {
viewModelScope.launch { privateAction()
}
suspend fun privateAction() {
f.collect {
liveData.value = it
}
}
@Test
fun example() = runBlockingTest {
viewModel.action()
viewModel.viewModelScope.coroutineContext[Job]!!.join()
assertEquals(viewModel.liveData.value, "Test")
}你也可以试试这个，
suspend fun <T> LiveData<T>.awaitValue(): T? {
return suspendCoroutine { cont ->
val observer = object : Observer<T> {
override fun onChanged(t: T?) {
removeObserver(this)
cont.resume(t)
}
}
observeForever(observer)
}
}
@Test
fun example() = runBlockingTest {
viewModel.action()
assertEquals(viewModel.liveData.awaitValue(), "Test")
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/58115153
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