【发布时间】：2018-10-12 09:46:14
【问题描述】：
设置：
在我们的项目中（在工作中 - 我无法发布真实代码），我们实现了干净的 MVVM。视图通过 LiveData 与 ViewModel 通信。 ViewModel 承载两种用例：做某事的“动作用例”和“状态更新用例”。反向通信是异步的（就动作反应而言）。它不像 API 调用，您可以从调用中获取结果。是BLE，所以写完特性后会有一个我们监听的通知特性。所以我们使用了大量的 Rx 来更新状态。它在 Kotlin 中。
视图模型：
@PerFragment
class SomeViewModel @Inject constructor(private val someActionUseCase: SomeActionUseCase,
someUpdateStateUseCase: SomeUpdateStateUseCase) : ViewModel() {
private val someState = MutableLiveData<SomeState>()
private val stateSubscription: Disposable
// region Lifecycle
init {
stateSubscription = someUpdateStateUseCase.state()
.subscribeIoObserveMain() // extension function
.subscribe { newState ->
someState.value = newState
})
}
override fun onCleared() {
stateSubscription.dispose()
super.onCleared()
}
// endregion
// region Public Functions
fun someState() = someState
fun someAction(someValue: Boolean) {
val someNewValue = if (someValue) "This" else "That"
someActionUseCase.someAction(someNewValue)
}
// endregion
}
更新状态用例：
@Singleton
class UpdateSomeStateUseCase @Inject constructor(
private var state: SomeState = initialState) {
private val statePublisher: PublishProcessor<SomeState> =
PublishProcessor.create()
fun update(state: SomeState) {
this.state = state
statePublisher.onNext(state)
}
fun state(): Observable<SomeState> = statePublisher.toObservable()
.startWith(state)
}
我们正在使用 Spek 进行单元测试。
@RunWith(JUnitPlatform::class)
class SomeViewModelTest : SubjectSpek<SomeViewModel>({
setRxSchedulersTrampolineOnMain()
var mockSomeActionUseCase = mock<SomeActionUseCase>()
var mockSomeUpdateStateUseCase = mock<SomeUpdateStateUseCase>()
var liveState = MutableLiveData<SomeState>()
val initialState = SomeState(initialValue)
val newState = SomeState(newValue)
val behaviorSubject = BehaviorSubject.createDefault(initialState)
subject {
mockSomeActionUseCase = mock()
mockSomeUpdateStateUseCase = mock()
whenever(mockSomeUpdateStateUseCase.state()).thenReturn(behaviorSubject)
SomeViewModel(mockSomeActionUseCase, mockSomeUpdateStateUseCase).apply {
liveState = state() as MutableLiveData<SomeState>
}
}
beforeGroup { setTestRxAndLiveData() }
afterGroup { resetTestRxAndLiveData() }
context("some screen") {
given("the action to open the screen") {
on("screen opened") {
subject
behaviorSubject.startWith(initialState)
it("displays the initial state") {
assertEquals(liveState.value, initialState)
}
}
}
given("some setup") {
on("some action") {
it("does something") {
subject.doSomething(someValue)
verify(mockSomeUpdateStateUseCase).someAction(someOtherValue)
}
}
on("action updating the state") {
it("displays new state") {
behaviorSubject.onNext(newState)
assertEquals(liveState.value, newState)
}
}
}
}
}
一开始我们使用的是 Observable 而不是 BehaviorSubject：
var observable = Observable.just(initialState)
...
whenever(mockSomeUpdateStateUseCase.state()).thenReturn(observable)
...
observable = Observable.just(newState)
assertEquals(liveState.value, newState)
而不是：
val behaviorSubject = BehaviorSubject.createDefault(initialState)
...
whenever(mockSomeUpdateStateUseCase.state()).thenReturn(behaviorSubject)
...
behaviorSubject.onNext(newState)
assertEquals(liveState.value, newState)
但是单元测试很不稳定。大多数情况下它们会通过（总是在孤立运行时），但有时它们会在运行整个套装时失败。考虑到它与 Rx 的异步特性有关，我们移至 BehaviourSubject 以便能够控制 onNext() 何时发生。当我们在本地机器上从 AndroidStudio 运行它们时，测试现在通过了，但它们在构建机器上仍然不稳定。重新启动构建通常会使它们通过。
失败的测试总是我们断言 LiveData 值的测试。所以嫌疑人是 LiveData、Rx、Spek 或它们的组合。
问题：是否有人有类似的使用 LiveData、Spek 或 Rx 编写单元测试的经历，您是否找到了解决这些脆弱性问题的编写方法？
........
使用的辅助函数和扩展函数：
fun instantTaskExecutorRuleStart() =
ArchTaskExecutor.getInstance().setDelegate(object : TaskExecutor() {
override fun executeOnDiskIO(runnable: Runnable) {
runnable.run()
}
override fun isMainThread(): Boolean {
return true
}
override fun postToMainThread(runnable: Runnable) {
runnable.run()
}
})
fun instantTaskExecutorRuleFinish() = ArchTaskExecutor.getInstance().setDelegate(null)
fun setRxSchedulersTrampolineOnMain() = RxAndroidPlugins.setInitMainThreadSchedulerHandler { Schedulers.trampoline() }
fun setTestRxAndLiveData() {
setRxSchedulersTrampolineOnMain()
instantTaskExecutorRuleStart()
}
fun resetTestRxAndLiveData() {
RxAndroidPlugins.reset()
instantTaskExecutorRuleFinish()
}
fun <T> Observable<T>.subscribeIoObserveMain(): Observable<T> =
subscribeOnIoThread().observeOnMainThread()
fun <T> Observable<T>.subscribeOnIoThread(): Observable<T> = subscribeOn(Schedulers.io())
fun <T> Observable<T>.observeOnMainThread(): Observable<T> =
observeOn(AndroidSchedulers.mainThread())
【问题讨论】：
标签： android unit-testing rx-java android-livedata spek