manuelvicnt

class ShotViewModelTest {
    // This CoroutineDispatcher is injected in the ViewModel and use case
    private val testCoroutineDispatcher = TestCoroutineDispatcher()

    @After
    fun tearDown() {
        testCoroutineDispatcher.cleanupTestCoroutines()
    }

    @Test

manuelvicnt

// Bad practice
class MyViewModel() {
    fun example() {
        // ------------------ code smell ---------
        viewModelScope.launch(Dispatchers.IO) { … } 
    }
}

// Inject Dispatchers as shown below!

manuelvicnt

@Singleton
@Component(modules = [FeedCacheModule::class, DatabaseModule::class])
interface AppComponent { ... }

@Module
object FeedCacheModule {

    @Provides
    fun feedCache(feedDatabase: FeedDatabase): FeedCache {
        return RoomFeedCache(database.feedDao())

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
class DefaultSessionAndUserEventRepository(
    private val userEventDataSource: UserEventDataSource,
    private val sessionRepository: SessionRepository
) : SessionAndUserEventRepository {

    override fun getObservableUserEvent(
        userId: String?,
        eventId: SessionId

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
// Simplified version of the real code
class SessionDetailViewModel(
    private val loadUserSessionUseCase: LoadUserSessionUseCase,
    ...
): ViewModel() {

    private fun listenForUserSessionChanges(sessionId: SessionId) {
        viewModelScope.launch {

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
override fun getObservableUserEvent(userId: String, eventId: SessionId): Flow<UserEventResult> {

    // 1) Create Flow with channelFlow
    return channelFlow<UserEventResult> {

        val eventDocument = firestore.collection(USERS_COLLECTION)
            .document(userId)
            .collection(EVENTS_COLLECTION)

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
class FirebaseAuthStateUserDataSource(...) : AuthStateUserDataSource {

    private val channel = ConflatedBroadcastChannel<Result<AuthenticatedUserInfo>>()

    private val listener: ((FirebaseAuth) -> Unit) = { auth ->
        // Data processing logic

        // Send the current user for observers

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
fun loginUser(userId: String?, password: String?, completion: Continuation<Any?>) {
    ...

    val continuation = completion as? LoginUserStateMachine ?: LoginUserStateMachine(completion)

    when(continuation.label) {
        0 -> {
            // Checks for failures

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
fun loginUser(userId: String?, password: String?, completion: Continuation<Any?>) {
    ...

    val continuation = completion as? LoginUserStateMachine ?: LoginUserStateMachine(completion)

    when(continuation.label) {
        ...
        2 -> {

manuelvicnt

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
fun loginUser(userId: String?, password: String?, completion: Continuation<Any?>) {

    class LoginUserStateMachine(
        // completion parameter is the callback to the function that called loginUser
        completion: Continuation<Any?>
    ): CoroutineImpl(completion) {
        // objects to store across the suspend function
        var user: User? = null