JoseAlcerreca

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
public class LiveDataTestUtil {
    public static <T> T getOrAwaitValue(final LiveData<T> liveData) throws InterruptedException {
        final Object[] data = new Object[1];
        final CountDownLatch latch = new CountDownLatch(1);
        Observer<T> observer = new Observer<T>() {
            @Override
            public void onChanged(@Nullable T o) {
                data[0] = o;

JoseAlcerreca

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
fun <T> LiveData<T>.getOrAwaitValue(
    time: Long = 2,
    timeUnit: TimeUnit = TimeUnit.SECONDS
): T {
    var data: T? = null
    val latch = CountDownLatch(1)
    val observer = object : Observer<T> {
        override fun onChanged(o: T?) {

JoseAlcerreca

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
@Test
fun isLiveDataEmitting_observeForever() {
    viewModel.setNewValue("foo")

    // This works but can be improved.
    viewModel.liveData2.observeForever { }

    // Passes because it's not a result of a Transformation:

JoseAlcerreca

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
fun isLiveDataEmitting() {
    viewModel.setNewValue("foo")

    assertEquals(viewModel.liveData1.value, "foo") // Passes
    
    assertEquals(viewModel.liveData2.value, "FOO") // Fails!
}

JoseAlcerreca

/* Copyright 2019 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */
class MyViewModel : ViewModel() {
    private val _liveData1 = MutableLiveData<String>()
    val liveData1: LiveData<String> = _liveData1

    // [Transformations.map] on liveData1 that converts the value to uppercase:
    val liveData2 = _liveData1.map { it.toUpperCase() }

    fun setNewValue(newValue: String) {

JoseAlcerreca

coroutineScope {
    launch { tasksRemoteDataSource.saveTask(it) }
    launch { tasksLocalDataSource.saveTask(it) }
}

JoseAlcerreca

fun View.showSnackbar(snackbarText: String, timeLength: Int) {
    Snackbar.make(this, snackbarText, timeLength).show()
}

JoseAlcerreca

object EspressoIdlingResource {

    fun increment() { // NO-OP }

    fun decrement() { // NO-OP }
}

JoseAlcerreca

suspend fun getTask(taskId: String): Result<Task> {

    EspressoIdlingResource.increment() // Set app as busy.

    // Get off the main thread or suspend
    return withContext(ioDispatcher) {         …
        EspressoIdlingResource.decrement() // Set app as idle.
        return@withContext data
    }
}

JoseAlcerreca

fun View.showSnackbar(snackbarText: String, timeLength: Int) {
    Snackbar.make(this, snackbarText, timeLength).run {
        addCallback(object: Snackbar.Callback() {
            override fun onShown(sb: Snackbar?) {
                EspressoIdlingResource.increment()
            }

            override fun onDismissed(transientBottomBar: Snackbar?, event: Int) {
                EspressoIdlingResource.decrement()
            }