Kotlin 高级 Android 开发 05.3：测试协程和 Jetpack 集成

$ git clone https://github.com/google-developer-training/advanced-android-testing.git
$ cd android-testing
$ git checkout end_codelab_2

    // Dependencies for Android instrumented unit tests
    androidTestImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:$coroutinesVersion"

@MediumTest
@RunWith(AndroidJUnit4::class)
@ExperimentalCoroutinesApi // LOOK HERE
class TaskDetailFragmentTest {

    //... Setup and teardown

    @Test
    fun activeTaskDetails_DisplayedInUi() = runBlockingTest{ // LOOK HERE
        // GIVEN - Add active (incomplete) task to the DB.
        val activeTask = Task("Active Task", "AndroidX Rocks", false)
        repository.saveTask(activeTask) // LOOK HERE Example of calling a suspend function

        // WHEN - Details fragment launched to display task.
        val bundle = TaskDetailFragmentArgs(activeTask.id).toBundle()
        launchFragmentInContainer<TaskDetailFragment>(bundle, R.style.AppTheme)

        // THEN - Task details are displayed on the screen.
        // Make sure that the title/description are both shown and correct.
        // Lots of Espresso code...
    }

    // More tests...
}

class FakeTestRepository : TasksRepository {

    var tasksServiceData: LinkedHashMap<String, Task> = LinkedHashMap()

    private val observableTasks = MutableLiveData<Result<List<Task>>>()


    // More code...

    override fun observeTasks(): LiveData<Result<List<Task>>> {
        runBlocking { refreshTasks() } // LOOK HERE
        return observableTasks
    }

    override suspend fun refreshTasks() {
        observableTasks.value = getTasks()
    }
    
    // More code...
}

@Test
fun completeTask_dataAndSnackbarUpdated() {
    // Create an active task and add it to the repository.
    val task = Task("Title", "Description")
    tasksRepository.addTasks(task)

    // Mark the task as complete task.
    tasksViewModel.completeTask(task, true)

    // Verify the task is completed.
   assertThat(tasksRepository.tasksServiceData[task.id]?.isCompleted, `is`(true))

    // Assert that the snackbar has been updated with the correct text.
    val snackbarText: Event<Int> =  tasksViewModel.snackbarText.getOrAwaitValue()
    assertThat(snackbarText.getContentIfNotHandled(), `is`(R.string.task_marked_complete))
}

@ExperimentalCoroutinesApi
val testDispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()

@ExperimentalCoroutinesApi
@Before
fun setupDispatcher() {
    Dispatchers.setMain(testDispatcher)
}

@ExperimentalCoroutinesApi
@After
fun tearDownDispatcher() {
    Dispatchers.resetMain()
    testDispatcher.cleanupTestCoroutines()
}

@ExperimentalCoroutinesApi
class MainCoroutineRule(val dispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()):
   TestWatcher(),
   TestCoroutineScope by TestCoroutineScope(dispatcher) {
   override fun starting(description: Description?) {
       super.starting(description)
       Dispatchers.setMain(dispatcher)
   }

   override fun finished(description: Description?) {
       super.finished(description)
       cleanupTestCoroutines()
       Dispatchers.resetMain()
   }
}

// REPLACE@ExperimentalCoroutinesApi
val testDispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()

@ExperimentalCoroutinesApi
@Before
fun setupDispatcher() {
    Dispatchers.setMain(testDispatcher)
}

@ExperimentalCoroutinesApi
@After
fun tearDownDispatcher() {
    Dispatchers.resetMain()
    testDispatcher.cleanupTestCoroutines()
}
// WITH
@ExperimentalCoroutinesApi
@get:Rule
var mainCoroutineRule = MainCoroutineRule()

class DefaultTasksRepository(
    private val tasksRemoteDataSource: TasksDataSource,
    private val tasksLocalDataSource: TasksDataSource,
    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO) : TasksRepository { ... }

// Set the main coroutines dispatcher for unit testing.
@ExperimentalCoroutinesApi
@get:Rule
var mainCoroutineRule = MainCoroutineRule()

@Before
fun createRepository() {
    tasksRemoteDataSource = FakeDataSource(remoteTasks.toMutableList())
    tasksLocalDataSource = FakeDataSource(localTasks.toMutableList())
    // Get a reference to the class under test.
    tasksRepository = DefaultTasksRepository(
    // HERE Swap Dispatcher.Unconfined
        tasksRemoteDataSource, tasksLocalDataSource, Dispatchers.Main
    )
}

// REPLACE
fun getTasks_requestsAllTasksFromRemoteDataSource() = runBlockingTest {

// WITH
fun getTasks_requestsAllTasksFromRemoteDataSource() = mainCoroutineRule.runBlockingTest {

// REPLACE
class StatisticsViewModel(application: Application) : AndroidViewModel(application) {

    private val tasksRepository = (application as TodoApplication).taskRepository

    // Rest of class
}

// WITH

class StatisticsViewModel(
    private val tasksRepository: TasksRepository
) : ViewModel() { 
    // Rest of class 
}

@Suppress("UNCHECKED_CAST")
class StatisticsViewModelFactory (
    private val tasksRepository: TasksRepository
) : ViewModelProvider.NewInstanceFactory() {
    override fun <T : ViewModel> create(modelClass: Class<T>) =
        (StatisticsViewModel(tasksRepository) as T)
}

// REPLACE
private val viewModel by viewModels<TasksViewModel>()

// WITH

private val viewModel by viewModels<StatisticsViewModel> {
    StatisticsViewModelFactory(
        (requireContext().applicationContext as TodoApplication).taskRepository
    )
}

@ExperimentalCoroutinesApi
class StatisticsViewModelTest {

    // Executes each task synchronously using Architecture Components.
    @get:Rule
    var instantExecutorRule = InstantTaskExecutorRule()

    // Set the main coroutines dispatcher for unit testing.
    @ExperimentalCoroutinesApi
    @get:Rule
    var mainCoroutineRule = MainCoroutineRule()

    // Subject under test
    private lateinit var statisticsViewModel: StatisticsViewModel

    // Use a fake repository to be injected into the view model.
    private lateinit var tasksRepository: FakeTestRepository

    @Before
    fun setupStatisticsViewModel() {
        // Initialise the repository with no tasks.
        tasksRepository = FakeTestRepository()

        statisticsViewModel = StatisticsViewModel(tasksRepository)
    }
}

fun refresh() {
   _dataLoading.value = true
       viewModelScope.launch {
           tasksRepository.refreshTasks()
           _dataLoading.value = false
       }
}

@Test
fun loadTasks_loading() {
    
    // Load the task in the view model.
    statisticsViewModel.refresh()

    // Then progress indicator is shown.
    assertThat(statisticsViewModel.dataLoading.getOrAwaitValue(), `is`(true))

    // Then progress indicator is hidden.
    assertThat(statisticsViewModel.dataLoading.getOrAwaitValue(), `is`(false))
}

fun refresh() {
   _dataLoading.value = true
   // YOU WANT TO CHECK HERE...
   viewModelScope.launch {
       tasksRepository.refreshTasks()
       _dataLoading.value = false
       // ...AND CHECK HERE.
   }
}

fun refresh() {
   _dataLoading.value = true
   // PAUSES EXECUTION HERE
   viewModelScope.launch {
       tasksRepository.refreshTasks()
       _dataLoading.value = false
   }
}

@Test
fun loadTasks_loading() {
    // Pause dispatcher so you can verify initial values.
    mainCoroutineRule.pauseDispatcher()

    // Load the task in the view model.
    statisticsViewModel.refresh()

    // Then assert that the progress indicator is shown.
    assertThat(statisticsViewModel.dataLoading.getOrAwaitValue(), `is`(true))

    // Execute pending coroutines actions.
    mainCoroutineRule.resumeDispatcher()

    // Then assert that the progress indicator is hidden.
    assertThat(statisticsViewModel.dataLoading.getOrAwaitValue(), `is`(false))
}

private var shouldReturnError = false

fun setReturnError(value: Boolean) {
    shouldReturnError = value
}

// Avoid import conflicts:
import com.example.android.architecture.blueprints.todoapp.data.Result
import com.example.android.architecture.blueprints.todoapp.data.Result.Error
import com.example.android.architecture.blueprints.todoapp.data.Result.Success


...

override suspend fun getTask(taskId: String, forceUpdate: Boolean): Result<Task> {
    if (shouldReturnError) {
        return Result.Error(Exception("Test exception"))
    }
    tasksServiceData[taskId]?.let {
        return Success(it)
    }
    return Error(Exception("Could not find task"))
}

override suspend fun getTasks(forceUpdate: Boolean): Result<List<Task>> {
    if (shouldReturnError) {
        return Error(Exception("Test exception"))
    }
    return Success(tasksServiceData.values.toList())
}

class StatisticsViewModel(
    private val tasksRepository: TasksRepository
) : ViewModel() {

    private val tasks: LiveData<Result<List<Task>>> = tasksRepository.observeTasks()

    // Other variables...    
  
    val error: LiveData<Boolean> = tasks.map { it is Error }
    val empty: LiveData<Boolean> = tasks.map { (it as? Success)?.data.isNullOrEmpty() }

    // Rest of the code...    
}

@Test
fun loadStatisticsWhenTasksAreUnavailable_callErrorToDisplay() {
    // Make the repository return errors.
    tasksRepository.setReturnError(true)
    statisticsViewModel.refresh()

    // Then empty and error are true (which triggers an error message to be shown).
    assertThat(statisticsViewModel.empty.getOrAwaitValue(), `is`(true))
    assertThat(statisticsViewModel.error.getOrAwaitValue(), `is`(true))
}

    androidTestImplementation "androidx.arch.core:core-testing:$archTestingVersion"

@ExperimentalCoroutinesApi
@RunWith(AndroidJUnit4::class)
@SmallTest
class TasksDaoTest {

    // Executes each task synchronously using Architecture Components.
    @get:Rule
    var instantExecutorRule = InstantTaskExecutorRule()

}

private lateinit var database: ToDoDatabase

@Before
fun initDb() {
    // Using an in-memory database so that the information stored here disappears when the
    // process is killed.
    database = Room.inMemoryDatabaseBuilder(
        getApplicationContext(),
        ToDoDatabase::class.java
    ).build()
}

@After
fun closeDb() = database.close()

@ExperimentalCoroutinesApi
@RunWith(AndroidJUnit4::class)
@SmallTest
class TasksDaoTest {

    // Executes each task synchronously using Architecture Components.
    @get:Rule
    var instantExecutorRule = InstantTaskExecutorRule()


    private lateinit var database: ToDoDatabase

    @Before
    fun initDb() {
        // Using an in-memory database so that the information stored here disappears when the
        // process is killed.
        database = Room.inMemoryDatabaseBuilder(
            getApplicationContext(),
            ToDoDatabase::class.java
        ).allowMainThreadQueries().build()
    }

    @After
    fun closeDb() = database.close()

}

@Test
fun insertTaskAndGetById() = runBlockingTest {
    // GIVEN - Insert a task.
    val task = Task("title", "description")
    database.taskDao().insertTask(task)

    // WHEN - Get the task by id from the database.
    val loaded = database.taskDao().getTaskById(task.id)

    // THEN - The loaded data contains the expected values.
    assertThat<Task>(loaded as Task, notNullValue())
    assertThat(loaded.id, `is`(task.id))
    assertThat(loaded.title, `is`(task.title))
    assertThat(loaded.description, `is`(task.description))
    assertThat(loaded.isCompleted, `is`(task.isCompleted))
}

import androidx.arch.core.executor.testing.InstantTaskExecutorRule
import androidx.room.Room
import androidx.test.core.app.ApplicationProvider.getApplicationContext
import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.filters.SmallTest
import com.example.android.architecture.blueprints.todoapp.data.Task
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.test.runBlockingTest
import org.hamcrest.CoreMatchers.`is`
import org.hamcrest.CoreMatchers.notNullValue
import org.hamcrest.MatcherAssert.assertThat
import org.junit.After
import org.junit.Before
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith

@Test
fun updateTaskAndGetById() {
    // 1. Insert a task into the DAO.

    // 2. Update the task by creating a new task with the same ID but different attributes.
    
    // 3. Check that when you get the task by its ID, it has the updated values.
}

@ExperimentalCoroutinesApi
@RunWith(AndroidJUnit4::class)
@MediumTest
class TasksLocalDataSourceTest {

    // Executes each task synchronously using Architecture Components.
    @get:Rule
    var instantExecutorRule = InstantTaskExecutorRule()

}

private lateinit var localDataSource: TasksLocalDataSource
private lateinit var database: ToDoDatabase

@Before
fun setup() {
    // Using an in-memory database for testing, because it doesn't survive killing the process.
    database = Room.inMemoryDatabaseBuilder(
        ApplicationProvider.getApplicationContext(),
        ToDoDatabase::class.java
    )
        .allowMainThreadQueries()
        .build()

    localDataSource =
        TasksLocalDataSource(
            database.taskDao(),
            Dispatchers.Main
        )
}

@ExperimentalCoroutinesApi
@RunWith(AndroidJUnit4::class)
@MediumTest
class TasksLocalDataSourceTest {

    private lateinit var localDataSource: TasksLocalDataSource
    private lateinit var database: ToDoDatabase


    // Executes each task synchronously using Architecture Components.
    @get:Rule
    var instantExecutorRule = InstantTaskExecutorRule()

    @Before
    fun setup() {
        // Using an in-memory database for testing, because it doesn't survive killing the process.
        database = Room.inMemoryDatabaseBuilder(
            ApplicationProvider.getApplicationContext(),
            ToDoDatabase::class.java
        )
            .allowMainThreadQueries()
            .build()

        localDataSource =
            TasksLocalDataSource(
                database.taskDao(),
                Dispatchers.Main
            )
    }

    @After
    fun cleanUp() {
        database.close()
    }
    
}

import com.example.android.architecture.blueprints.todoapp.data.source.TasksDataSource
import com.example.android.architecture.blueprints.todoapp.data.Result.Success
import com.example.android.architecture.blueprints.todoapp.data.Task
import com.example.android.architecture.blueprints.todoapp.data.succeeded
import kotlinx.coroutines.runBlocking
import org.hamcrest.CoreMatchers.`is`
import org.junit.Assert.assertThat
import org.junit.Test

// runBlocking is used here because of https://github.com/Kotlin/kotlinx.coroutines/issues/1204
// TODO: Replace with runBlockingTest once issue is resolved
@Test
fun saveTask_retrievesTask() = runBlocking {
    // GIVEN - A new task saved in the database.
    val newTask = Task("title", "description", false)
    localDataSource.saveTask(newTask)

    // WHEN  - Task retrieved by ID.
    val result = localDataSource.getTask(newTask.id)

    // THEN - Same task is returned.
    assertThat(result.succeeded, `is`(true))
    result as Success
    assertThat(result.data.title, `is`("title"))
    assertThat(result.data.description, `is`("description"))
    assertThat(result.data.isCompleted, `is`(false))
}

assertThat(result.succeeded, `is`(true))
result as Success

@Test
fun completeTask_retrievedTaskIsComplete(){
    // 1. Save a new active task in the local data source.

    // 2. Mark it as complete.

    // 3. Check that the task can be retrieved from the local data source and is complete.

}

@RunWith(AndroidJUnit4::class)
@LargeTest
class TasksActivityTest {

    private lateinit var repository: TasksRepository

    @Before
    fun init() {
        repository = ServiceLocator.provideTasksRepository(getApplicationContext())
        runBlocking {
            repository.deleteAllTasks()
        }
    }

    @After
    fun reset() {
        ServiceLocator.resetRepository()
    }
}

@Test
fun editTask() = runBlocking {
    // Set initial state.
    repository.saveTask(Task("TITLE1", "DESCRIPTION"))
    
    // Start up Tasks screen.
    val activityScenario = ActivityScenario.launch(TasksActivity::class.java)


    // Espresso code will go here.


    // Make sure the activity is closed before resetting the db:
    activityScenario.close()
}

@Test
fun editTask() = runBlocking {

    // Set initial state.
    repository.saveTask(Task("TITLE1", "DESCRIPTION"))
    
    // Start up Tasks screen.
    val activityScenario = ActivityScenario.launch(TasksActivity::class.java)

    // Click on the task on the list and verify that all the data is correct.
    onView(withText("TITLE1")).perform(click())
    onView(withId(R.id.task_detail_title_text)).check(matches(withText("TITLE1")))
    onView(withId(R.id.task_detail_description_text)).check(matches(withText("DESCRIPTION")))
    onView(withId(R.id.task_detail_complete_checkbox)).check(matches(not(isChecked())))

    // Click on the edit button, edit, and save.
    onView(withId(R.id.edit_task_fab)).perform(click())
    onView(withId(R.id.add_task_title_edit_text)).perform(replaceText("NEW TITLE"))
    onView(withId(R.id.add_task_description_edit_text)).perform(replaceText("NEW DESCRIPTION"))
    onView(withId(R.id.save_task_fab)).perform(click())

    // Verify task is displayed on screen in the task list.
    onView(withText("NEW TITLE")).check(matches(isDisplayed()))
    // Verify previous task is not displayed.
    onView(withText("TITLE1")).check(doesNotExist())
    // Make sure the activity is closed before resetting the db.
    activityScenario.close()
}

import androidx.test.core.app.ActivityScenario
import androidx.test.core.app.ApplicationProvider.getApplicationContext
import androidx.test.espresso.Espresso.onView
import androidx.test.espresso.action.ViewActions.click
import androidx.test.espresso.action.ViewActions.replaceText
import androidx.test.espresso.assertion.ViewAssertions.doesNotExist
import androidx.test.espresso.assertion.ViewAssertions.matches
import androidx.test.espresso.matcher.ViewMatchers.*
import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.filters.LargeTest
import com.example.android.architecture.blueprints.todoapp.data.Task
import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
import com.example.android.architecture.blueprints.todoapp.tasks.TasksActivity
import kotlinx.coroutines.runBlocking
import org.hamcrest.core.IsNot.not
import org.junit.After
import org.junit.Before
import org.junit.Test
import org.junit.runner.RunWith

onView(withId(R.id.next_screen_button)).perform(click()) // Step 1
onView(withId(R.id.screen_description)).check(matches(withText("The next screen"))) // Step 2

implementation "androidx.test.espresso:espresso-idling-resource:$espressoVersion"

    testOptions.unitTests {
        includeAndroidResources = true
        returnDefaultValues = true
    }

object EspressoIdlingResource {

    private const val RESOURCE = "GLOBAL"

    @JvmField
    val countingIdlingResource = CountingIdlingResource(RESOURCE)

    fun increment() {
        countingIdlingResource.increment()
    }

    fun decrement() {
        if (!countingIdlingResource.isIdleNow) {
            countingIdlingResource.decrement()
        }
    }
}

EspressoIdlingResource.increment()
try {
     doSomethingThatTakesALongTime()
} finally {
    EspressoIdlingResource.decrement()
}

inline fun <T> wrapEspressoIdlingResource(function: () -> T): T {
    // Espresso does not work well with coroutines yet. See
    // https://github.com/Kotlin/kotlinx.coroutines/issues/982
    EspressoIdlingResource.increment() // Set app as busy.
    return try {
        function()
    } finally {
        EspressoIdlingResource.decrement() // Set app as idle.
    }
}

wrapEspressoIdlingResource {
    doWorkThatTakesALongTime()
}

    override suspend fun getTasks(forceUpdate: Boolean): Result<List<Task>> {
        wrapEspressoIdlingResource {
            if (forceUpdate) {
                try {
                    updateTasksFromRemoteDataSource()
                } catch (ex: Exception) {
                    return Result.Error(ex)
                }
            }
            return tasksLocalDataSource.getTasks()
        }
    }

class DataBindingIdlingResource : IdlingResource {
    // List of registered callbacks
    private val idlingCallbacks = mutableListOf<IdlingResource.ResourceCallback>()
    // Give it a unique id to work around an Espresso bug where you cannot register/unregister
    // an idling resource with the same name.
    private val id = UUID.randomUUID().toString()
    // Holds whether isIdle was called and the result was false. We track this to avoid calling
    // onTransitionToIdle callbacks if Espresso never thought we were idle in the first place.
    private var wasNotIdle = false

    lateinit var activity: FragmentActivity

    override fun getName() = "DataBinding $id"

    override fun isIdleNow(): Boolean {
        val idle = !getBindings().any { it.hasPendingBindings() }
        @Suppress("LiftReturnOrAssignment")
        if (idle) {
            if (wasNotIdle) {
                // Notify observers to avoid Espresso race detector.
                idlingCallbacks.forEach { it.onTransitionToIdle() }
            }
            wasNotIdle = false
        } else {
            wasNotIdle = true
            // Check next frame.
            activity.findViewById<View>(android.R.id.content).postDelayed({
                isIdleNow
            }, 16)
        }
        return idle
    }

    override fun registerIdleTransitionCallback(callback: IdlingResource.ResourceCallback) {
        idlingCallbacks.add(callback)
    }

    /**
     * Find all binding classes in all currently available fragments.
     */
    private fun getBindings(): List<ViewDataBinding> {
        val fragments = (activity as? FragmentActivity)
            ?.supportFragmentManager
            ?.fragments

        val bindings =
            fragments?.mapNotNull {
                it.view?.getBinding()
            } ?: emptyList()
        val childrenBindings = fragments?.flatMap { it.childFragmentManager.fragments }
            ?.mapNotNull { it.view?.getBinding() } ?: emptyList()

        return bindings + childrenBindings
    }
}

private fun View.getBinding(): ViewDataBinding? = DataBindingUtil.getBinding(this)

/**
 * Sets the activity from an [ActivityScenario] to be used from [DataBindingIdlingResource].
 */
fun DataBindingIdlingResource.monitorActivity(
    activityScenario: ActivityScenario<out FragmentActivity>
) {
    activityScenario.onActivity {
        this.activity = it
    }
}

/**
 * Sets the fragment from a [FragmentScenario] to be used from [DataBindingIdlingResource].
 */
fun DataBindingIdlingResource.monitorFragment(fragmentScenario: FragmentScenario<out Fragment>) {
    fragmentScenario.onFragment {
        this.activity = it.requireActivity()
    }
}

    // An idling resource that waits for Data Binding to have no pending bindings.
    private val dataBindingIdlingResource = DataBindingIdlingResource()

    /**
     * Idling resources tell Espresso that the app is idle or busy. This is needed when operations
     * are not scheduled in the main Looper (for example when executed on a different thread).
     */
    @Before
    fun registerIdlingResource() {
        IdlingRegistry.getInstance().register(EspressoIdlingResource.countingIdlingResource)
        IdlingRegistry.getInstance().register(dataBindingIdlingResource)
    }

    /**
     * Unregister your Idling Resource so it can be garbage collected and does not leak any memory.
     */
    @After
    fun unregisterIdlingResource() {
        IdlingRegistry.getInstance().unregister(EspressoIdlingResource.countingIdlingResource)
        IdlingRegistry.getInstance().unregister(dataBindingIdlingResource)
    }

  @Test
    fun editTask() = runBlocking {
        repository.saveTask(Task("TITLE1", "DESCRIPTION"))

        // Start up Tasks screen.
        val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
        dataBindingIdlingResource.monitorActivity(activityScenario) // LOOK HERE

        // Rest of test...
    }

@RunWith(AndroidJUnit4::class)
@LargeTest
class TasksActivityTest {

    private lateinit var repository: TasksRepository

    // An idling resource that waits for Data Binding to have no pending bindings.
    private val dataBindingIdlingResource = DataBindingIdlingResource()

    @Before
    fun init() {
        repository =
            ServiceLocator.provideTasksRepository(
                getApplicationContext()
            )
        runBlocking {
            repository.deleteAllTasks()
        }
    }

    @After
    fun reset() {
        ServiceLocator.resetRepository()
    }

    /**
     * Idling resources tell Espresso that the app is idle or busy. This is needed when operations
     * are not scheduled in the main Looper (for example when executed on a different thread).
     */
    @Before
    fun registerIdlingResource() {
        IdlingRegistry.getInstance().register(EspressoIdlingResource.countingIdlingResource)
        IdlingRegistry.getInstance().register(dataBindingIdlingResource)
    }

    /**
     * Unregister your Idling Resource so it can be garbage collected and does not leak any memory.
     */
    @After
    fun unregisterIdlingResource() {
        IdlingRegistry.getInstance().unregister(EspressoIdlingResource.countingIdlingResource)
        IdlingRegistry.getInstance().unregister(dataBindingIdlingResource)
    }

        @Test
        fun editTask() = runBlocking {

            // Set initial state.
            repository.saveTask(Task("TITLE1", "DESCRIPTION"))
            
            // Start up Tasks screen.
            val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
            dataBindingIdlingResource.monitorActivity(activityScenario)
            // Click on the task on the list and verify that all the data is correct.
            onView(withText("TITLE1")).perform(click())
            onView(withId(R.id.task_detail_title_text)).check(matches(withText("TITLE1")))
            onView(withId(R.id.task_detail_description_text)).check(matches(withText("DESCRIPTION")))
            onView(withId(R.id.task_detail_complete_checkbox)).check(matches(not(isChecked())))

            // Click on the edit button, edit, and save.
            onView(withId(R.id.edit_task_fab)).perform(click())
            onView(withId(R.id.add_task_title_edit_text)).perform(replaceText("NEW TITLE"))
            onView(withId(R.id.add_task_description_edit_text)).perform(replaceText("NEW DESCRIPTION"))
            onView(withId(R.id.save_task_fab)).perform(click())

            // Verify task is displayed on screen in the task list.
            onView(withText("NEW TITLE")).check(matches(isDisplayed()))
            // Verify previous task is not displayed.
            onView(withText("TITLE1")).check(doesNotExist())
            // Make sure the activity is closed before resetting the db.
            activityScenario.close()
        }

}

 @Test
    fun createOneTask_deleteTask() {

        // 1. Start TasksActivity.
       
        // 2. Add an active task by clicking on the FAB and saving a new task.
        
        // 3. Open the new task in a details view.
        
        // 4. Click delete task in menu.

        // 5. Verify it was deleted.

        // 6. Make sure the activity is closed.
        
    }

@RunWith(AndroidJUnit4::class)
@LargeTest
class AppNavigationTest {

    private lateinit var tasksRepository: TasksRepository

    // An Idling Resource that waits for Data Binding to have no pending bindings.
    private val dataBindingIdlingResource = DataBindingIdlingResource()

    @Before
    fun init() {
        tasksRepository = ServiceLocator.provideTasksRepository(getApplicationContext())
    }

    @After
    fun reset() {
        ServiceLocator.resetRepository()
    }

    /**
     * Idling resources tell Espresso that the app is idle or busy. This is needed when operations
     * are not scheduled in the main Looper (for example when executed on a different thread).
     */
    @Before
    fun registerIdlingResource() {
        IdlingRegistry.getInstance().register(EspressoIdlingResource.countingIdlingResource)
        IdlingRegistry.getInstance().register(dataBindingIdlingResource)
    }

    /**
     * Unregister your idling resource so it can be garbage collected and does not leak any memory.
     */
    @After
    fun unregisterIdlingResource() {
        IdlingRegistry.getInstance().unregister(EspressoIdlingResource.countingIdlingResource)
        IdlingRegistry.getInstance().unregister(dataBindingIdlingResource)
    }

}

@Test
fun tasksScreen_clickOnDrawerIcon_OpensNavigation() {
    // Start the Tasks screen.
    val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
    dataBindingIdlingResource.monitorActivity(activityScenario)

    // 1. Check that left drawer is closed at startup.

    // 2. Open drawer by clicking drawer icon.

    // 3. Check if drawer is open.

    // When using ActivityScenario.launch(), always call close()
    activityScenario.close()
}

@Test
fun taskDetailScreen_doubleUpButton() = runBlocking {
    val task = Task("Up button", "Description")
    tasksRepository.saveTask(task)

    // Start the Tasks screen.
    val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
    dataBindingIdlingResource.monitorActivity(activityScenario)

    // 1. Click on the task on the list.
    
    // 2. Click on the edit task button.
   
    // 3. Confirm that if we click Up button once, we end up back at the task details page.
   
    // 4. Confirm that if we click Up button a second time, we end up back at the home screen.
   
    // When using ActivityScenario.launch(), always call close().
    activityScenario.close()
}


@Test
fun taskDetailScreen_doubleBackButton() = runBlocking {
    val task = Task("Back button", "Description")
    tasksRepository.saveTask(task)

    // Start Tasks screen.
    val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
    dataBindingIdlingResource.monitorActivity(activityScenario)

    // 1. Click on the task on the list.
    
    // 2. Click on the Edit task button.
    
    // 3. Confirm that if we click Back once, we end up back at the task details page.
    
    // 4. Confirm that if we click Back a second time, we end up back at the home screen.
    
    // When using ActivityScenario.launch(), always call close()
    activityScenario.close()
}

fun <T : Activity> ActivityScenario<T>.getToolbarNavigationContentDescription()
        : String {
    var description = ""
    onActivity {
        description =
            it.findViewById<Toolbar>(R.id.toolbar).navigationContentDescription as String
    }
    return description
}

onView(
    withContentDescription(
        activityScenario
            .getToolbarNavigationContentDescription()
    )
).perform(click())

onView(withId(R.id.drawer_layout))
    .check(matches(isOpen(Gravity.START))) // Left drawer is open. 
onView(withId(R.id.drawer_layout))
    .check(matches(isClosed(Gravity.START))) // Left Drawer is closed.        

pressBack()

// You'll need to import androidx.test.espresso.Espresso.pressBack.