如何在单元测试中处理模拟的RxJava2可观察抛出异常

Question

过去几周我一直在使用MVP在Android中在Kotlin做TDD.事情进展顺利.

我使用Mockito来模拟类,但我似乎无法克服如何实现我想要运行的测试之一.

以下是我的测试:

1. 调用api,接收数据列表,然后显示列表. loadAllPlacesTest()
2. 调用api,接收空数据,然后显示列表. loadEmptyPlacesTest()
3. 调用api,路上会发生一些异常,然后显示错误信息. loadExceptionPlacesTest()

我成功地测试了#1和#2.问题在于#3,我不确定如何在代码中进行测试.

RestApiInterface.kt

interface RestApiInterface {

@GET(RestApiManager.PLACES_URL)
fun getPlacesPagedObservable(
        @Header("header_access_token") accessToken: String?,
        @Query("page") page: Int?
): Observable<PlacesWrapper>
}

RestApiManager.kt 实现接口的管理器类如下所示:

open class RestApiManager: RestApiInterface{
var api: RestApiInterface
    internal set
internal var retrofit: Retrofit
init {
    val logging = HttpLoggingInterceptor()
    // set your desired log level
    logging.setLevel(HttpLoggingInterceptor.Level.BODY)

    val client = okhttp3.OkHttpClient().newBuilder()
            .readTimeout(60, TimeUnit.SECONDS)
            .connectTimeout(60, TimeUnit.SECONDS)
            .addInterceptor(LoggingInterceptor())  
            .build()


    retrofit = Retrofit.Builder()
            .baseUrl(BASE_URL)
            .client(client)
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())//very important for RXJAVA and retrofit
            .build()
    api = retrofit.create(RestApiInterface::class.java)
}
override fun getPlacesPagedObservable(accessToken: String?, page: Int?): Observable<PlacesWrapper> {
    //return throw Exception("sorry2")
    return api.getPlacesPagedObservable(
            accessToken,
            page)
}
}

}

这是我的单元测试:

class PlacesPresenterImplTest : AndroidTest(){

lateinit var presenter:PlacesPresenterImpl
lateinit var view:PlacesView
lateinit var apiManager:RestApiManager
//lateinit var apiManager:RestApiManager

val EXCEPTION_MESSAGE1 = "SORRY"

val MANY_PLACES = Arrays.asList(PlaceItem(), PlaceItem());
var EXCEPTION_PLACES = Arrays.asList(PlaceItem(), PlaceItem());


val manyPlacesWrapper = PlacesWrapper(MANY_PLACES)
var exceptionPlacesWrapper = PlacesWrapper(EXCEPTION_PLACES)
val emptyPlacesWrapper = PlacesWrapper(Collections.emptyList())

@After
fun clear(){
    RxJavaPlugins.reset()
}
@Before
fun init(){
    //MOCKS THE subscribeOn(Schedulers.io()) to use the same thread the test is being run on
    //Schedulers.trampoline() runs the test in the same thread used by the test
    RxJavaPlugins.setIoSchedulerHandler { t -> Schedulers.trampoline() }

    view = Mockito.mock<PlacesView>(PlacesView::class.java)
    apiManager = Mockito.mock(RestApiManager::class.java)
    presenter = PlacesPresenterImpl(view,context(), Bundle(), Schedulers.trampoline())
    presenter.apiManager = apiManager

    //exceptionPlacesWrapper = throw Exception(EXCEPTION_MESSAGE1);
}


@Test
fun loadAllPlacesTest() {
    Mockito.`when`(apiManager.getPlacesPagedObservable(Mockito.anyString(), Mockito.anyInt())).thenReturn(Observable.just(manyPlacesWrapper))

    presenter.__populate()
    Mockito.verify(view, Mockito.atLeastOnce()).__showLoading()
    Mockito.verify(view, Mockito.atLeastOnce())._showList()
    Mockito.verify(view).__hideLoading()
    Mockito.verify(view).__showFullScreenMessage(Mockito.anyString())
}

@Test
fun loadEmptyPlacesTest() {

    Mockito.`when`(apiManager.getPlacesPagedObservable(Mockito.anyString(), Mockito.anyInt())).thenReturn(Observable.just(emptyPlacesWrapper))
    presenter.__populate()
    Mockito.verify(view, Mockito.atLeastOnce()).__showLoading()
    Mockito.verify(view, Mockito.atLeastOnce())._showList()
    Mockito.verify(view).__hideLoading()
    Mockito.verify(view).__showFullScreenMessage(Mockito.anyString())
}

@Test
fun loadExceptionPlacesTest() {
    Mockito.`when`(apiManager.getPlacesPagedObservable(Mockito.anyString(), Mockito.anyInt())).thenThrow(Exception(EXCEPTION_MESSAGE1))
    presenter.__populate()
    Mockito.verify(view, Mockito.atLeastOnce()).__showLoading()
    Mockito.verify(view, Mockito.never())._showList()
    Mockito.verify(view).__hideLoading()
    Mockito.verify(view).__showFullScreenMessage(EXCEPTION_MESSAGE1)
}
}

PlacesPresenterImpl.kt 这是演示者.

   class PlacesPresenterImpl
constructor(var view: PlacesView, var context: Context, var savedInstanceState:Bundle?, var mainThread: Scheduler)
: BasePresenter(), BasePresenterInterface, PlacesPresenterInterface {

lateinit var apiManager:RestApiInterface
var placeListRequest: Disposable? = null


override fun __firstInit() {
    apiManager = RestApiManager()
}

override fun __init(context: Context, savedInstanceState: Bundle, view: BaseView?) {
    this.view = view as PlacesView
    if (__isFirstTimeLoad())
        __firstInit()
}


override fun __destroy() {
    placeListRequest?.dispose()
}

override fun __populate() {
    _callPlacesApi()
}


override fun _callPlacesApi() {
    view.__showLoading()
    apiManager.getPlacesPagedObservable("", 0)
            .subscribeOn(Schedulers.io())
            .observeOn(mainThread)
            .subscribe (object : DisposableObserver<PlacesWrapper>() {
                override fun onNext(placesWrapper: PlacesWrapper) {
                    placesWrapper?.let {
                        val size = placesWrapper.place?.size
                        view.__hideLoading()
                        view._showList()
                        System.out.println("Great I found " + size + " records of places.")
                        view.__showFullScreenMessage("Great I found " + size + " records of places.")
                    }
                    System.out.println("onNext()")
                }

                override fun onError(e: Throwable) {
                    System.out.println("onError()")
                    //e.printStackTrace()
                    view.__hideLoading()
                    if (ExceptionsUtil.isNoNetworkException(e)){
                        view.__showFullScreenMessage("So sad, can not connect to network to get place list.")
                    }else{
                        view.__showFullScreenMessage("Oops, something went wrong. ["+e.localizedMessage+"]")
                    }

                    this.dispose()
                }

                override fun onComplete() {
                    this.dispose()
                    //System.out.printf("onComplete()")
                }
            })


}

private fun _getEventCompletionObserver(): DisposableObserver<String> {
    return object : DisposableObserver<String>() {
        override fun onNext(taskType: String) {
            //_log(String.format("onNext %s task", taskType))
        }

        override fun onError(e: Throwable) {
            //_log(String.format("Dang a task timeout"))
            //Timber.e(e, "Timeout Demo exception")
        }

        override fun onComplete() {
            //_log(String.format("task was completed"))
        }
    }
}}

问题/问题 loadExceptionPlacesTest()

1. 我不确定为什么代码不会转到Presenter的onError(). 如果我错了,请纠正我,但这就是我的想法:

•     a - `apiManager.getPlacesPagedObservable("",0)`observable本身抛出一个异常,这就是为什么`.subscribe()`不能发生/继续,并且观察者的方法不会被调用,
•     b - 当observable中的操作遇到类似JSONException的异常时,它只会转到onError()

2. 因为loadExceptionPlacesTest()我认为上面的1b是让演示者onError()被调用并让测试通过的方法.它是否正确？如果是在测试中如何做到这一点.如果不是,你们可以指出我错过了什么或做错了吗？

Answer 1

我将把它留在这里以供将来参考,并且能够详细说明,即使我已在评论中回答.

您要完成的是将onError流放入流中.不幸的是,通过嘲笑它:

Mockito.`when`(apiManager.getPlacesPagedObservable(
                   Mockito.anyString(), Mockito.anyInt()))
                           .thenThrow(Exception(EXCEPTION_MESSAGE1))

你实际上是在告诉Mockito设置你的模拟,只是调用apiManager.getPlacesPagedObservable(anystring, anystring)应该抛出一个异常.

确实在Rx流中抛出异常将导致整个流停止并最终进入该onError方法.但是,这正是您正在使用的方法的问题.抛出异常时,您不在流中.

相反,你想要做的就是告诉Mockito,一旦你打电话给apiManager.getPlacesPagedObservable(anystring, anystring)你想要返回一个最终会出现的流onError.这可以通过以下方式轻松实现Observable.error():

Mockito.`when`(apiManager.getPlacesPagedObservable(
               Mockito.a??nyString(), Mockito.anyInt()))
                    .thenReturn(Observable.error(
                                Exception(EXCEPTION_MESSAGE1)))

(您可能需要在此处添加此部分中的某些类型信息Observable.error(),您可能还需要使用其他内容而不是可观察的内容 - 单个,可完成等)

上面的模拟将告诉Mockito设置你的模拟返回一个可以在订阅时出错的observable.这将反过来将您的订阅者直接放入onError具有指定异常的流中.