A talk a gave on the Israeli Android Academy. Sept 2019.

1. Android Automated Testing

2. Definition
The use of software separate from the software
being tested to control the execution of tests and
the comparison of actual outcomes with predicted
outcomes
https://en.wikipedia.org/wiki/Test_automation

3. App
adb install app

4. App
Instrumentation
Tests
Local Tests
adb install app
adb install tests

5. About Me
https://github.com/roisagiv
https://www.linkedin.com/in/roisagiv/

6. About You

7. • Experienced in developing Android apps
• Familiar with:
• LiveData
• ViewModel
• Coroutines
• Room
• Heard about / Some experience with testing
About You

8. Agenda
• Android testing tools landscape
• Benefits and challenges of automated testing
• Tips & Tricks

9. Android Testing Landscape

10. Android Testing Landscape
Two types of runtimes:
• "Unit Tests" - local machine
• Instrumentation - Device / Emulator
Powered by JUnit

11. The build process

12. Local Tests
Fast - Runs on the JVM (Local machine)
• No DEX
• No APK Installation
Limited - No access to Android SDK / components
• Views, Context, SharedPreferences, res...
• *Can be simulated (Robolectrics & others) or mocked.

13. Local Tests
app
src
androidTest
main
test

14. Example

15. My Weight Tracker
API
https://github.com/roisagiv/WeightTracker-Android

16. Architecture
Activity / Fragment

17. Architecture
Activity / Fragment
ViewModel

18. Architecture
Activity / Fragment
ViewModel
Repository

19. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)

20. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)Local (Room)

21. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)Local (Room)

22. interface AirtableAPI {
@GET("./")
suspend fun records(): Response<RecordsApiResponse>
@POST("./")
suspend fun create(@Body fields: CreateRecordBody): Response<AirtableRecord>
companion object {
fun build(baseUrl: String, apiKey: String): AirtableAPI {
...
}
}
}
data class RecordsApiResponse(val records: List<AirtableRecord>)
data class AirtableRecord(val id: String, val fields: Map<String, String>)
data class CreateRecordBody(val fields: Map<String, Any>)

23. interface AirtableAPI {
@GET("./")
suspend fun records(): Response<RecordsApiResponse>
@POST("./")
suspend fun create(@Body fields: CreateRecordBody): Response<AirtableRecord>
companion object {
fun build(baseUrl: String, apiKey: String): AirtableAPI {
...
}
}
}
data class RecordsApiResponse(val records: List<AirtableRecord>)
data class AirtableRecord(val id: String, val fields: Map<String, String>)
data class CreateRecordBody(val fields: Map<String, Any>)

24. class AirtableAPITest {
@get:Rule
var mockWebServer = MockWebServer()
@Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
// Act
...
// Assert
...
}
}

25. class AirtableAPITest {
@get:Rule
var mockWebServer = MockWebServer()
@Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
// Act
...
// Assert
...
}
}

26. class AirtableAPITest {
@get:Rule
var mockWebServer = MockWebServer()
@Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
// Act
...
// Assert
...
}
}

27. class AirtableAPITest {
@get:Rule
var mockWebServer = MockWebServer()
@Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
// Act
...
// Assert
...
}
}

28. @Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
val client = AirtableAPI.build(
mockWebServer.url("/").toString(),
API_KEY
)
mockWebServer.enqueue(
MockResponse()
.setResponseCode(200)
.setBody(Resources.read("records_success.json"))
)
// Act
...
// Assert
...
}

29. @Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
// Act
val clientResponse = client.records()
// Assert
...
}

30. @Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
...
// Assert
assertThat(mockWebServer.requestCount).isEqualTo(1)
val request = mockWebServer.takeRequest()
assertThat(request.path).isEqualTo("/")
assertThat(request.headers["Authorization"])
.isEqualTo("Bearer $API_KEY")
assertThat(clientResponse.isSuccessful).isTrue()
val records = clientResponse.body()?.records ?: listOf()
assertThat(records).hasSize(3)
val record = records[0]
assertThat(record.fields).hasSize(6)
assertThat(record.fields["Weight"]).isEqualTo("80")
assertThat(record.fields["Date"]).isEqualTo("2019-06-03T21:03:00.000Z
}

31. Tada!

32. MockWebServer
class AirtableAPITest {
@get:Rule
var mockWebServer = MockWebServer()
@Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
...
}
}
testImplementation "com.squareup.okhttp3:mockwebserver:$rootProject.okhttpVersion"

33. @Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
mockWebServer.enqueue(
MockResponse()
.setResponseCode(200)
.setBody(Resources.read("records_success.json"))
)
// Act
...
// Assert
assertThat(mockWebServer.requestCount).isEqualTo(1)
val request = mockWebServer.takeRequest()
assertThat(request.path).isEqualTo("/")
assertThat(request.headers["Authorization"]).isEqualTo("Bearer $API_KEY")
...
}

34. @Test
fun recordsShouldReturnListOfWeightRecords() = runBlocking {
// Arrange
...
mockWebServer.enqueue(
MockResponse()
.setResponseCode(200)
.setBody(Resources.read("records_success.json"))
)
// Act
...
// Assert
assertThat(mockWebServer.requestCount).isEqualTo(1)
val request = mockWebServer.takeRequest()
assertThat(request.path).isEqualTo("/")
assertThat(request.headers["Authorization"]).isEqualTo("Bearer $API_KEY")
...
}

35. {
"records": [
{
"id": "recx6FjYsKNY5R5sF",
"fields": {
"UserName": "fsdfsdf",
"Date": "2019-06-03T21:03:00.000Z",
"Weight": 80,
"Week Avg": 81.5,
"Created time": "2019-06-29T20:58:53.000Z",
"Last modified time": "2019-07-06T11:02:34.000Z"
},
"createdTime": "2019-06-29T20:58:53.000Z"
},
{
"id": "recVzvGP6aXci0Lly",
"fields": {
"UserName": "Aenean.euismod.mauris@rutrum.net",
"Date": "2020-01-10T00:48:24.000Z",
"Weight": 101,
"Week Avg": 82.5,
"Notes": "hymenaeos. Mauris ut quam vel",
"Created time": "2019-07-06T11:05:54.000Z",
"Last modified time": "2019-07-06T11:05:54.000Z"
},
"createdTime": "2019-07-06T11:05:54.000Z"
},
{
"id": "rec8hgWP8HFByqnSz",
"fields": {
app
src
test
resources
records_success.json

36. @Test
fun recordsShouldReturnFailureResponseInCaseOfServerError() = runBlocking {
// Arrange
mockWebServer.enqueue(MockResponse().setResponseCode(500))
...
// Act
...
// Assert
...
}

37. FIRST - Principles of Unit Tests
• Fast
• Isolated
• Repeatable
• Self-Validating
• Thorough / Timely

38. Recap / Questions?
• "Unit Tests" / Local Tests
• Test a single class (AirtableAPI)
• The structure of a test (AAA)
• FIRST principals
• MockWebServer

39. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)Local (Room)

40. @Database(entities = [WeightItem::class], version = 1)
@TypeConverters(DateConverters::class)
abstract class WeightsDatabase : RoomDatabase() {
abstract fun weightItemsDao(): WeightItemsDao
}
@Entity(tableName = "WeightItems")
data class WeightItem(
@PrimaryKey val id: String,
val date: OffsetDateTime,
val weight: Double,
val notes: String?
)
@Dao
interface WeightItemsDao {
@Insert(onConflict = REPLACE)
suspend fun save(item: WeightItem)
@Query("SELECT * from WeightItems")
suspend fun all(): List<WeightItem>
}

41. @Database(entities = [WeightItem::class], version = 1)
@TypeConverters(DateConverters::class)
abstract class WeightsDatabase : RoomDatabase() {
abstract fun weightItemsDao(): WeightItemsDao
}
@Entity(tableName = "WeightItems")
data class WeightItem(
@PrimaryKey val id: String,
val date: OffsetDateTime,
val weight: Double,
val notes: String?
)
@Dao
interface WeightItemsDao {
@Insert(onConflict = REPLACE)
suspend fun save(item: WeightItem)
@Query("SELECT * from WeightItems")
suspend fun all(): List<WeightItem>
}

42. @Database(entities = [WeightItem::class], version = 1)
@TypeConverters(DateConverters::class)
abstract class WeightsDatabase : RoomDatabase() {
abstract fun weightItemsDao(): WeightItemsDao
}
@Entity(tableName = "WeightItems")
data class WeightItem(
@PrimaryKey val id: String,
val date: OffsetDateTime,
val weight: Double,
val notes: String?
)
@Dao
interface WeightItemsDao {
@Insert(onConflict = REPLACE)
suspend fun save(item: WeightItem)
@Query("SELECT * from WeightItems")
suspend fun all(): List<WeightItem>
}

43. Instrumentation Tests
Easy(ish) - Access to android SDK / components
• Context, SharedPreferences, etc.
• UI & Resources
Slow(er) - Android toolchain
• DEX
• APK install every run

44. Instrumentation Tests
app
src
androidTest
main
test

45. @RunWith(AndroidJUnit4::class)
class WeightsDatabaseTest {
@get:Rule
var weightsDatabaseRule = WeightsDatabaseRule()
@Test
fun newSavedItemShouldBeReturnInAllQuery() = runBlocking {
// Arrange
...
// Act
...
// Assert
...
}
}

46. @Test
fun newSavedItemShouldBeReturnInAllQuery() = runBlocking {
// Arrange
val dao = weightsDatabaseRule.weightItemsDao
val newEntry = WeightItem(
id = Random.nextInt().toString(),
date = OffsetDateTime.now(),
weight = Random.nextDouble(),
notes = ""
)
// Act
dao.save(newEntry)
// Assert
val items = dao.all()
assertThat(items).hasSize(1)
assertThat(items[0].weight).isEqualTo(newEntry.weight)
}

47. @Test
fun newSavedItemShouldBeReturnInAllQuery() = runBlocking {
// Arrange
val dao = weightsDatabaseRule.weightItemsDao
val newEntry = WeightItem(
id = Random.nextInt().toString(),
date = OffsetDateTime.now(),
weight = Random.nextDouble(),
notes = ""
)
// Act
dao.save(newEntry)
// Assert
val items = dao.all()
assertThat(items).hasSize(1)
assertThat(items[0].weight).isEqualTo(newEntry.weight)
}

48. @Test
fun newSavedItemShouldBeReturnInAllQuery() = runBlocking {
// Arrange
val dao = weightsDatabaseRule.weightItemsDao
val newEntry = WeightItem(
id = Random.nextInt().toString(),
date = OffsetDateTime.now(),
weight = Random.nextDouble(),
notes = ""
)
// Act
dao.save(newEntry)
// Assert
val items = dao.all()
assertThat(items).hasSize(1)
assertThat(items[0].weight).isEqualTo(newEntry.weight)
}

49. class WeightsDatabaseRule : TestRule {
internal lateinit var weightItemsDao: WeightItemsDao
private lateinit var db: WeightsDatabase
override fun apply(base: Statement?, description: Description?): Statement {
return object : Statement() {
override fun evaluate() {
...
try {
base?.evaluate()
} finally {
...
}
...
}
}
}
}

50. class WeightsDatabaseRule : TestRule {
internal lateinit var weightItemsDao: WeightItemsDao
private lateinit var db: WeightsDatabase
override fun apply(base: Statement?, description: Description?): Statement {
return object : Statement() {
override fun evaluate() {
db = Room.inMemoryDatabaseBuilder(
InstrumentationRegistry.getInstrumentation().targetContext,
WeightsDatabase::class.java
).build()
weightItemsDao = db.weightItemsDao()
try {
base?.evaluate()
} finally {
db.close()
}
}
}
}

51. Recap / Questions?
• Instrumentation Tests
• Test a single component (Room)
• InMemory database
• JUnit rule
Tip
• Skip local tests, focus on instrumentation tests

52. The Test Pyramid

53. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)Local (Room)

54. interface WeightsRepository {
suspend fun allItems(): LiveData<Resource<List<WeightItem>>>
suspend fun save(item: NewWeightItem): LiveData<Resource<WeightItem?>>
}

55. class LiveWeightsRepository(
private val airtableAPI: AirtableAPI,
private val weightItemsDao: WeightItemsDao
) : WeightsRepository {
override suspend fun allItems(): LiveData<Resource<List<WeightItem>>> {
return object : NetworkBoundResource<List<WeightItem>, RecordsApiResponse>() {
...
}.build().asLiveData()
}
override suspend fun save(item: NewWeightItem): LiveData<Resource<WeightItem?>> {
return object : NetworkBoundResource<WeightItem?, AirtableRecord>() {
...
}.build().asLiveData()
}
}

56. @RunWith(AndroidJUnit4::class)
class LiveWeightsRepositoryTest {
@get:Rule
var mockWebServer = MockWebServer()
@get:Rule
var weightsDatabase = WeightsDatabaseRule()
@get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
@Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
}
}

57. @RunWith(AndroidJUnit4::class)
class LiveWeightsRepositoryTest {
@get:Rule
var mockWebServer = MockWebServer()
@get:Rule
var weightsDatabase = WeightsDatabaseRule()
@get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
@Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
}
}

58. @Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
// Arrange
val body = Assets.read(
"records_success.json",
InstrumentationRegistry.getInstrumentation().context
)
mockWebServer.enqueue(
MockResponse().setResponseCode(200).setBody(body)
)
val client = AirtableAPI.build(
mockWebServer.url("").toString(), API_KEY
)
val weightItemsDao = weightsDatabase.weightItemsDao
var observer: TestObserver<Resource<List<WeightItem>>>? = null
val repository = LiveWeightsRepository(client, weightItemsDao)
// Act
...
// Assert
...
}

59. @Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
// Arrange
...
var observer: TestObserver<Resource<List<WeightItem>>>? = null
val repository = LiveWeightsRepository(client, weightItemsDao)
// Act
runBlocking {
observer = repository.allItems().test(2)
}
// Assert
...
}

60. @Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
// Arrange
...
// Act
runBlocking {
observer = repository.allItems().test(2)
}
// Assert
assertThat(mockWebServer.takeRequest()).isNotNull()
assertThat(mockWebServer.requestCount).isEqualTo(1)
observer?.await()
observer?.assertValues {
assertThat(it[0].status).isEqualTo(Status.LOADING)
assertThat(it[0].data).hasSize(0)
assertThat(it[1].status).isEqualTo(Status.SUCCESS)
assertThat(it[1].data).hasSize(3)
}
}

61. class TestObserver<T>(expectedCount: Int) : Observer<T> {
private val values = mutableListOf<T>()
private val latch: CountDownLatch = CountDownLatch(expectedCount)
override fun onChanged(value: T) {
values.add(value)
latch.countDown()
}
fun assertValues(function: (List<T>) -> Unit) {
function.invoke(values)
}
fun await(timeout: Long = 5, unit: TimeUnit = TimeUnit.SECONDS) {
if (!latch.await(timeout, unit)) {
throw TimeoutException()
}
}
}

62. class TestObserver<T>(expectedCount: Int) : Observer<T> {
...
}
fun <T> LiveData<T>.test(expectedCount: Int = 1) =
TestObserver<T>(expectedCount).also {
observeForever(it)
}

63. @RunWith(AndroidJUnit4::class)
class LiveWeightsRepositoryTest {
@get:Rule
var mockWebServer = MockWebServer()
@get:Rule
var weightsDatabase = WeightsDatabaseRule()
@get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
@Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
}
}

64. @RunWith(AndroidJUnit4::class)
class LiveWeightsRepositoryTest {
@get:Rule
var mockWebServer = MockWebServer()
@get:Rule
var weightsDatabase = WeightsDatabaseRule()
@get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
@Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
}
@Test
fun givenSavedItemsAllShouldUpdateDB() {
}
}

65. @Test
fun givenSavedItemsAllShouldUpdateDB() {
// Arrange
...
val weightItemsDao = weightsDatabase.weightItemsDao
runBlocking {
weightItemsDao.save(
WeightItem(
id = "recVzvGP6aXci0Lly",
date = OffsetDateTime.parse("2019-06-12T21:00:00.000Z"),
weight = 172.42,
notes = ""
)
)
}
// Act
...
// Assert
...
}

66. @Test
fun givenSavedItemsAllShouldUpdateDB() {
// Arrange
...
// Act
...
// Assert
assertThat(mockWebServer.takeRequest()).isNotNull()
assertThat(mockWebServer.requestCount).isEqualTo(1)
observer?.await()
observer?.assertValues {
assertThat(it[0].status).isEqualTo(Status.LOADING)
assertThat(it[0].data).hasSize(1)
assertThat(it[1].status).isEqualTo(Status.SUCCESS)
assertThat(it[1].data).hasSize(3)
}
}

67. @RunWith(AndroidJUnit4::class)
class LiveWeightsRepositoryTest {
...
@Test
fun givenCleanStateAllShouldCallNetworkAndSaveInDB() {
}
@Test
fun givenSavedItemsAllShouldUpdateDB() {
}
@Test
fun saveShouldPerformNetworkAndSaveInDB() {
}
}

68. @Test
fun saveShouldPerformNetworkAndSaveInDB() {
// Arrange
...
val repository = LiveWeightsRepository(client, weightItemsDao)
// Act
runBlocking {
observer = repository
.save(NewWeightItem(OffsetDateTime.now(), 10.0, null))
.test(2)
}
// Assert
...
runBlocking {
assertThat(historyDataItemDao.all()).hasSize(1)
}
}

69. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)Local (Room)

70. abstract class HistoryViewModel : ViewModel() {
abstract val state: LiveData<ViewState>
abstract fun refresh()
sealed class ViewState {
object Loading : ViewState()
data class Error(val error: Throwable? = null) : ViewState()
data class Success(val list: List<WeightItem>) : ViewState()
}
}

71. class LiveHistoryViewModel(private val repository: WeightsRepository) :
HistoryViewModel() {
private val refreshAction: MutableLiveData<Unit> = MutableLiveData()
override val state: LiveData<ViewState> = refreshAction.switchMap {
...
}
override fun refresh() {
refreshAction.postValue(Unit)
}
}

72. class LiveHistoryViewModel(private val repository: WeightsRepository) :
HistoryViewModel() {
private val refreshAction: MutableLiveData<Unit> = MutableLiveData()
override val state: LiveData<ViewState> = refreshAction.switchMap {
liveData<ViewState>(
context = viewModelScope.coroutineContext + Dispatchers.IO
) {
emitSource(repository.allItems().map {
when (it.status) {
Status.LOADING -> ViewState.Loading
Status.SUCCESS -> ViewState.Success(it.data!!)
Status.ERROR -> ViewState.Error()
}
})
}
}
override fun refresh() { ... }
}

73. @RunWith(AndroidJUnit4::class)
class HistoryViewModelTest {
@get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
@get:Rule
var mockWebServer = MockWebServer()
@get:Rule
var weightsDatabase = WeightsDatabaseRule()
@Test
fun refreshShouldFetchFromServer() { ... }
@Test
fun givenServerErrorShouldReturnError() { ... }
}

74. @Test
fun refreshShouldFetchFromServer() {
// Arrange
val body = Assets.read(
"records_success.json",
InstrumentationRegistry.getInstrumentation().context
)
mockWebServer.enqueue(MockResponse().setResponseCode(200).setBody(body))
val client = AirtableAPI.build(mockWebServer.url("").toString(), API_KEY)
val repository = LiveWeightsRepository(client, weightsDatabase.weightItemsDao)
val viewModel = LiveHistoryViewModel(repository)
// Act
...
// Assert
...
}

75. @Test
fun refreshShouldFetchFromServer() {
// Arrange
...
val viewModel = LiveHistoryViewModel(repository)
// Act
val observer = viewModel.state.test(expectedCount = 2)
viewModel.refresh()
observer.await()
// Assert
...
}

76. @Test
fun refreshShouldFetchFromServer() {
...
// Assert
assertThat(mockWebServer.requestCount).isEqualTo(1)
observer.assertValues {
assertThat(it).hasSize(2)
assertThat(it[0]).isSameInstanceAs(HistoryViewModel.ViewState.Loading)
val items = it[1] as? HistoryViewModel.ViewState.Success
assertThat(items?.list).hasSize(3)
assertThat(items?.list?.get(0)?.id).isEqualTo("recx6FjYsKNY5R5sF")
assertThat(items?.list?.get(0)?.date).isEqualTo(
OffsetDateTime.parse(
"2019-06-03T21:03:00.000Z",
DateTimeFormatter.ISO_OFFSET_DATE_TIME
)
)
}
}

77. @Test
fun givenServerErrorShouldReturnError() {
// Arrange
mockWebServer.enqueue(MockResponse().setResponseCode(400))
val client = AirtableAPI.build(mockWebServer.url("").toString(), API_KEY)
val repository = LiveWeightsRepository(client, weightsDatabase.weightItemsDao)
val viewModel = LiveHistoryViewModel(repository)
// Act
val observer = viewModel.state.test(expectedCount = 2)
viewModel.refresh()
// Assert
observer.await()
assertThat(mockWebServer.requestCount).isEqualTo(1)
observer.assertValues {
assertThat(it).hasSize(2)
assertThat(it[0]).isSameInstanceAs(HistoryViewModel.ViewState.Loading)
val error = it[1] as? HistoryViewModel.ViewState.Error
assertThat(error).isNotNull()
}
}

78. The Test Pyramid

79. The Test Pyramid

80. The Test Pyramid

82. The Modern Test Pyramid (Trophy)

83. Recap / Questions?
• Integration Tests
• Test couple of components together
• TestObserver & InstantTaskExecutorRule
• Modern test pyramid
Tips
• Integration tests increase confidence
• Unit tests are disposable

84. Architecture
Activity / Fragment
ViewModel
Repository
Network (Retrofit)Local (Room)

85. class HistoryActivity : AppCompatActivity() {
private var linearLayoutManager: LinearLayoutManager? = null
private var adapter: HistoryRecyclerAdapter? = null
private val viewModel by viewModel<HistoryViewModel>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
...
}
override fun onStart() {
super.onStart()
viewModel.refresh()
}
}

86. class HistoryActivity : AppCompatActivity() {
private var linearLayoutManager: LinearLayoutManager? = null
private var adapter: HistoryRecyclerAdapter? = null
private val viewModel by viewModel<HistoryViewModel>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
...
}
override fun onStart() {
super.onStart()
viewModel.refresh()
}
}

87. class HistoryActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
...
viewModel.state.observe(this, Observer { state ->
when (state) {
is HistoryViewModel.ViewState.Error -> {
}
is HistoryViewModel.ViewState.Loading -> {
progressBar.visibility = View.VISIBLE
}
is HistoryViewModel.ViewState.Success -> {
progressBar.visibility = View.GONE
adapter?.submitList(state.list)
}
}
})
}
}

88. @RunWith(AndroidJUnit4::class)
class HistoryActivityTest {
@get:Rule
val activityRule = ActivityTestRule(
HistoryActivity::class.java, false, false
)
@get:Rule
val animationsRule = DisableAnimationsRule()
@get:Rule
val permissionRule: GrantPermissionRule =
GrantPermissionRule.grant(WRITE_EXTERNAL_STORAGE)
@get:Rule
val screenshotRule = ScreenshotRule()
private var viewModel: MockHistoryViewModel = MockHistoryViewModel()
@Before
fun before() { ... }
}

89. @RunWith(AndroidJUnit4::class)
class HistoryActivityTest {
...
private var viewModel: MockHistoryViewModel = MockHistoryViewModel()
@Before
fun before() {
viewModel = MockHistoryViewModel()
loadKoinModules(module {
viewModel<HistoryViewModel> { viewModel }
})
}
@Test
fun successStateShouldDisplayListOfItems() { ... }
...
}

90. class MockHistoryViewModel : HistoryViewModel() {
private val internalState: MutableLiveData<ViewState> = MutableLiveData()
override val state: LiveData<ViewState> = internalState
override fun refresh() = Unit
fun postViewState(viewState: ViewState) {
internalState.postValue(viewState)
}
}

91. @Test
fun successStateShouldDisplayListOfItems() {
// Arrange
activityRule.launchActivity(Intent())
// Act
viewModel.postViewState(createSuccessState())
// Assert
InstrumentationRegistry.getInstrumentation().waitForIdleSync()
onView(withId(R.id.recycler_history_items)).perform(
RecyclerHelpers.waitUntil(
RecyclerHelpers.hasItemCount(greaterThan(0))
)
)
assertRecyclerViewItemCount(R.id.recycler_history_items, 5)
screenshotRule.takeScreenshot()
}

92. private fun createSuccessState(): HistoryViewModel.ViewState.Success {
val items: List<WeightItem> = listOf(
WeightItem( ... ),
WeightItem( ... ),
WeightItem( ... ),
WeightItem( ... ),
WeightItem( ... )
)
return HistoryViewModel.ViewState.Success(items)
}

93. api27-1080x1920x2.625-en/HistoryActivityTest-successStateShouldDisplayListOfItems.png

94. @Test
fun loadingStateShouldDisplayProgressBar() {
// Arrange
activityRule.launchActivity(Intent())
// Act
viewModel.postViewState(HistoryViewModel.ViewState.Loading)
// Assert
assertDisplayed(R.id.progressBar)
screenshotRule.takeScreenshot()
}

95. api27-1080x1920x2.625-en/HistoryActivityTest-loadingStateShouldDisplayProgressBar.png

96. Recap / Questions?
• Unit test for the UI
• Mock the ViewModel
• Screenshots
Tip
• Helps verifying different UI states - loading, error,
empty, etc.

97. End to End tests
Automated the user experience
• Multiple screens
• Minimal to none mocks / stubs / etc.
• Real server*
• FIRST principals

98. My Weight Tracker

99. My Weight Tracker
Production
E2E

100. @RunWith(AndroidJUnit4::class)
class AddWeightE2ETest {
@Before
fun before() = runBlocking { ... }
@Test
fun addNewWeight() {
val uiDevice =
UiDevice.getInstance(InstrumentationRegistry.getInstrumentation())
ApplicationRobot.launchApp()
val historyRobot = HistoryRobot(uiDevice)
historyRobot.assertPageDisplayed()
historyRobot.assertNumberOfItemsInList(5)
historyRobot.navigateToAddWeight()
val addWeightRobot = AddWeightRobot(uiDevice)
addWeightRobot.assertPageDisplayed()

101. @Test
fun addNewWeight() {
val uiDevice =
UiDevice.getInstance(InstrumentationRegistry.getInstrumentation())
ApplicationRobot.launchApp()
val historyRobot = HistoryRobot(uiDevice)
historyRobot.assertPageDisplayed()
historyRobot.assertNumberOfItemsInList(5)
historyRobot.navigateToAddWeight()
val addWeightRobot = AddWeightRobot(uiDevice)
addWeightRobot.assertPageDisplayed()
addWeightRobot.typeWeight("12.34")
addWeightRobot.save()
historyRobot.assertPageDisplayed()
historyRobot.assertNumberOfItemsInList(6)
}
}

102. class HistoryRobot(private val uiDevice: UiDevice) {
fun assertPageDisplayed() {
assertDisplayed(R.string.app_name)
}
fun assertNumberOfItemsInList(expected: Int) {
uiDevice.findObject(UiSelector().textContains("Test Node 1"))
.waitForExists(500)
onView(withContentDescription(R.string.content_description_history_list))
.check(RecyclerViewItemCountAssertion(expected))
}
fun navigateToAddWeight() {
onView(withContentDescription(R.string.content_description_add_weight))
.perform(click())
}
}

103. class AddWeightRobot(private val uiDevice: UiDevice) {
fun assertPageDisplayed() {
uiDevice.findObject(UiSelector().textContains("SAVE"))
.waitForExists(5000)
assertDisplayed("SAVE")
}
fun typeWeight(weight: String) {
onView(withContentDescription(R.string.content_description_weight))
.perform(typeText(weight))
closeSoftKeyboard()
}
fun save() {
onView(withContentDescription(R.string.content_description_save_button))
.perform(click())
}
}

104. @Before
fun before() = runBlocking {
val airtable =
AirtableBatchAPI.build(BuildConfig.AIRTABLE_E2E_URL,
BuildConfig.AIRTABLE_E2E_KEY)
val records = airtable.records()
assertThat(records.isSuccessful).isTrue()
records.body()?.records?.map { it.id }?.let {
if (it.isNotEmpty()) {
assertThat(airtable.delete(it).isSuccessful).isTrue()
}
}
val body = Assets.read(
"create_records_e2e_body.json",
InstrumentationRegistry.getInstrumentation().context
)
val response = airtable.create(
Gson().fromJson(body, JsonObject::class.java)
)
assertThat(response.isSuccessful).isTrue()
}

105. interface AirtableBatchAPI {
@GET("./")
suspend fun records(): Response<RecordsApiResponse>
@POST("./")
suspend fun create(@Body body: JsonObject): Response<Unit>
@DELETE("./")
suspend fun delete(@Query("records[]") records: List<String>): Response<Unit>
companion object {
fun build(baseUrl: String, apiKey: String): AirtableBatchAPI {
...
}
}
}

106. Recap / Questions?
• End to End tests simulate the user
• Separated environment
• Server state
Tip
• Existing app without tests? start with E2E tests.

107. The Test Pyramid

108. The Test Pyramid
Development
Quality

109. Thank You!
• https://martinfowler.com/articles/practical-test-pyramid.html
• https://kentcdodds.com/blog/write-tests
• https://dhh.dk/2014/tdd-is-dead-long-live-testing.html
• https://medium.com/@copyconstruct/testing-in-production-the-safe-
way-18ca102d0ef1
• https://twitter.com/thepracticaldev/status/733908215021199360
• https://github.com/goldbergyoni/javascript-testing-best-practices
https://github.com/roisagivhttps://www.linkedin.com/in/roisagiv/