android - 使用 Repository + LiveData + Coroutines 进行 ViewModel 单元测试
问题描述
所以我对如何对我的 ViewModel 实施单元测试感到困惑。我正在使用改造来获取我的 API 并使用存储库。
视图模型.kt
@HiltViewModel
class MoviesViewModel @Inject constructor(private val moviesRepository: MoviesRepository) :
ViewModel() {
private val _navigatetoDetail = MutableLiveData<Movies?>()
fun getPopularMovies() = liveData(Dispatchers.Default) {
emit(Resource.loading(null))
try {
emit(Resource.success(moviesRepository.getPopularMovies()))
} catch (e: Exception) {
emit(
Resource.error(
null,
e.message ?: "Unknown Error"
)
)
Log.e("viewModel", "popularMovies error: ${e.message}")
}
}
fun getMovieDetails(movie_id: String) = liveData(Dispatchers.Default) {
emit(Resource.loading(null))
try {
emit(Resource.success(moviesRepository.getMovieDetails(movie_id)))
} catch (e: Exception) {
emit(
Resource.error(
null,
e.message ?: "Unknown Error"
)
)
Log.e("viewModel", "movieDetails error: ${e.message}")
}
}
fun navigatetoDetail(): LiveData<Movies?> {
return _navigatetoDetail
}
fun onMovieClicked(movies: Movies?) {
_navigatetoDetail.value = movies
}
fun onMovieDetailNavigated() {
_navigatetoDetail.value = null
}
存储库.kt
class MoviesRepository @Inject constructor(private var apiInterface: ApiInterface) {
init {
apiInterface = ApiBuilder.createService()
}
suspend fun getPopularMovies() = apiInterface.getPopularMovies()
suspend fun getMovieDetails(movie_id: String) = apiInterface.getMovieDetails(movie_id)
suspend fun getPopularTvShows() = apiInterface.getPopularTvShows()
suspend fun getTvShowDetails(tvshow_id: String) = apiInterface.getTvShowDetails(tvshow_id)
api接口.kt
interface ApiInterface {
@GET("/3/movie/popular?api_key=$API_KEY&language=en-US")
suspend fun getPopularMovies(): Envelope<List<Movies>>
@GET("/3/movie/{movie_id}?api_key=$API_KEY&language=en-US")
suspend fun getMovieDetails(@Path("movie_id") movie_id: String?): Movies
@GET("3/tv/popular?api_key=$API_KEY&language=en-US&page=1")
suspend fun getPopularTvShows(): Envelope<List<TvShows>>
@GET("/3/tv/{tvshow_id}?api_key=$API_KEY&language=en-US")
suspend fun getTvShowDetails(@Path("tvshow_id") tvshow_id: String?): TvShows
我已经尝试通过如下方式测试我的 ViewModel:
@Test
fun testGetPopularMovies() = coroutinesTestRule.testDispatcher.runBlockingTest {
val moviesList = viewModel.getPopularMovies().value
viewModel.getPopularMovies().observeForever(observer)
verify(observer).onChanged(argumentCaptor.capture())
assertEquals(20, moviesList?.data?.results?.size)
}
但它在viewModel.getPopularMovies().observeForever(observer)上返回 NullPointerException
解决方案
这是等待实时数据结果的扩展功能。在您的测试包下使用以下代码创建 koltin 扩展函数。
import androidx.annotation.VisibleForTesting
import androidx.lifecycle.LiveData
import androidx.lifecycle.Observer
import java.util.concurrent.CountDownLatch
import java.util.concurrent.TimeUnit
import java.util.concurrent.TimeoutException
@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
}
这是示例视图模型类测试。LoginViewmodel 类扩展了 AndroidViewModel 而不是 ViewModel。
import androidx.arch.core.executor.testing.InstantTaskExecutorRule
import androidx.test.core.app.ApplicationProvider
import androidx.test.ext.junit.runners.AndroidJUnit4
import com.mymaskreminder.ui.getOrAwaitValue
import org.junit.Assert
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith
@RunWith(AndroidJUnit4::class)
class LoginViewModelTest {
@get:Rule
var instantExecutorRule = InstantTaskExecutorRule()
@Test
fun sendLoginRequest() {
val loginViewModel = LoginViewModel(ApplicationProvider.getApplicationContext())
loginViewModel.sendLoginRequest("test@gmail.com", "12345")
//shadowOf(Looper.getMainLooper()).idle()
val value_error = loginViewModel.loginErrorResponse.getOrAwaitValue()
Assert.assertEquals(value_error.toString(),
"Unauthorized !"
)
}
}
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