Droidcon - Android Testing Strategy

Testing an Android application was always hard. In the past couple of years we got access to better tools, but we still rely a lot on architecture and design decisions in order to properly test an Android application. This talk will discuss the layers of automated testing an Android application should have, from End-to-end, Component, Integration to Unit tests. Also we will discuss BDD, TDD and Clean Architecture as tools to implement those layers.

Transcript

1. Android Testing Strategy Marcelo Benites
2. Why is it so hard to test an Android application?
3. No access to Android components constructor (Activity, Service, Application, Content Provider and Broadcast Receiver).
4. It is hard to fake Android OS events during testing (Battery Level, Location, Sensors etc...).
5. Android emulator is slow.
6. How do we solve those problems?
7. Clean Architecture
8. Domain • Business Logic • No implementation details (HTTP, SQLite, Bluetooth, etc...) • No external dependencies (including Android SDK)
9. Data • Simple adapter to a data source: Http, File System, Bluetooth, WebSocket, Push etc... • Should not be complex. Move complexity to the Domain • No external dependencies (including Android SDK)
10. Presentation • Presenter, Controller, ViewModel • No external dependencies (including Android SDK)
11. External Dependencies • Android SDK • RxJava, Fragment, Activity, Room, Retrofit, OKHttp, Dagger, etc...
12. Controller Presenter Use Case Implementation Callback <i> Use Case <i> Flow of control Domain Gateway <i> Gateway Implementation Data Presentation
13. Testing Strategy
14. Testing Strategy • Unit Tests - Test Presentation, Domain and Data in isolation. • Integration Tests - Test Data and Presentation interaction with External Dependencies. • Component Tests - Test Presentation, Domain and Data interaction using Test Doubles (Mock, Fake, Spy, Stub) for External Dependencies. • End-to-End Tests - Test Presentation, Domain Data and External Dependencies interaction.
16. Show me the code!
17. Conference Application
18. BDD
19. As a user I want to see conference details
20. Given a conference is registered with name Droidcon When I open conference application Then I see Droidcon on the screen
21. TDD
22. Unit Tests Domain Data Presentation
23. Domain First!
24. State
25. data class State<T>( val name: Name, val value: T? = null ) { enum class Name { IDLE, LOADING, LOADED, ERROR } } Idle Loading Loaded Error
26. Threading
27. interface Dispatcher { fun dispatch(execute: () -> Unit, error: (Throwable) -> Unit) fun dispatch(execute: () -> Unit) }
28. Data Contract
29. interface ConferenceGateway { fun getConference(): Conference } data class Conference(val id: String, val name: String)
30. Arrange, Act, Assert
31. Arrange
32. @Test fun `Given a registered conference When start is called Then should emit loaded state with conference`() { val conference = Conference("1", "Droidcon") val stateMachine = ConferenceStateMachine( FakeDispatcher(), FakeConferenceGateway(conference) ) val listenerMock = mockk<(State<Conference, GatewayError>) -> Unit>() stateMachine.addStateChangedListener(listenerMock) stateMachine.start() verifyOrder { listenerMock.invoke(State(State.Name.LOADING)) listenerMock.invoke(State(State.Name.LOADED, conference)) } }
33. Act
34. @Test fun `Given a conference When start is called Then should emit loaded state with conference`() { val conference = Conference("1", "Droidcon") val stateMachine = ConferenceStateMachine( FakeDispatcher(), FakeConferenceGateway(conference) ) val listenerMock = mockk<(State<Conference, GatewayError>) -> Unit>() stateMachine.addStateChangedListener(listenerMock) stateMachine.start() verifyOrder { listenerMock.invoke(State(State.Name.LOADING)) listenerMock.invoke(State(State.Name.LOADED, conference)) } }
35. Assert
36. @Test fun `Given a conference When start is called Then should emit loaded state with conference`() { val conference = Conference("1", "Droidcon") val stateMachine = ConferenceStateMachine( FakeDispatcher(), FakeConferenceGateway(conference) ) val listenerMock = mockk<(State<Conference, GatewayError>) -> Unit>() stateMachine.addStateChangedListener(listenerMock) stateMachine.start() verifyOrder { listenerMock.invoke(State(State.Name.LOADING)) listenerMock.invoke(State(State.Name.LOADED, conference)) } }
37. Test fails!
38. Make it pass.
39. class ConferenceStateMachine( private val conferenceGateway: ConferenceGateway, private val dispatcher: Dispatcher ) : StateMachine<Conference>() { override fun start() { loadConference() } private fun loadConference() { dispatcher.dispatch({ moveToLoading() moveToLoaded(conferenceGateway.getConference()) }, { moveToError(it) }) } }
40. Presentation
41. MVP (for the sake of simplicity)
42. View Contract
43. interface ConferenceView { fun hideLoading() fun showLoading() fun hideError() fun showError() fun showConferenceName(name: String) fun hideConferenceName() }
44. Arrange
45. @Test fun `Given a loaded conference When state is updated Then show conference name`() { val view = mockk<ConferenceView>() val presenter = ConferencePresenter(FakeDispatcher(), view) presenter.invoke(State(State.Name.LOADED, Conference("1", "Droidcon"))) verify { view.hideError() view.hideLoading() view.showConferenceName("Droidcon") } }
46. Act
47. @Test fun `Given a loaded conference When state is updated Then show conference name`() { val view = mockk<ConferenceView>() val presenter = ConferencePresenter(FakeDispatcher(), view) presenter.invoke(State(State.Name.LOADED, Conference("1", "Droidcon"))) verify { view.hideError() view.hideLoading() view.showConferenceName("Droidcon") } }
48. Assert
49. @Test fun `Given a loaded conference When state is updated Then show conference name`() { val view = mockk<ConferenceView>(relaxed = true) val presenter = ConferencePresenter(FakeDispatcher(), view) presenter.invoke(State(State.Name.LOADED, Conference("1", "Droidcon"))) verify { view.hideError() view.hideLoading() view.showConferenceName("Droidcon") } }
50. Data
51. Integration Tests Data Fake DB Fake External Service
52. Arrange
53. OkHttp and MockWebServer
54. @Test fun `When conference is requested Then call conference endpoint with GET method`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val gateway = OkHttpConferenceGateway(baseUrl, OkHttpClient()) val json = """ { "id": "1", "name": "Droidcon" } """ server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val conference = gateway.getConference() assertEquals(Conference("1", "Droidcon"), conference) val request = server.takeRequest() assertEquals("GET", request.method) assertEquals("/conference", request.path) server.shutdown() }
55. Act
56. @Test fun `When conference is requested Then call conference endpoint with GET method`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val gateway = OkHttpConferenceGateway(baseUrl, OkHttpClient()) val json = """ { "id": "1", "name": "Droidcon" } """.trimIndent() server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val conference = gateway.getConference() assertEquals(Conference("1", "Droidcon"), conference) val request = server.takeRequest() assertEquals("GET", request.method) assertEquals("/conference", request.path) server.shutdown() }
57. Assert
58. @Test fun `When conference is requested Then call conference endpoint with GET method`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val gateway = OkHttpConferenceGateway(baseUrl, OkHttpClient()) val json = """ { "id": "1", "name": "Droidcon" } """.trimIndent() server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val conference = gateway.getConference() assertEquals(Conference("1", "Droidcon"), conference) val request = server.takeRequest() assertEquals("GET", request.method) assertEquals("/conference", request.path) server.shutdown() }
59. Component Tests Domain Data Fake DB Fake External Service Presentation Fake GUI
61. Dependency Injection
62. interface DependencyManager { val conferenceStateMachine: StateMachine<Conference> val mainDispatcher: Dispatcher } interface ViewContainer { val dependencyManager: DependencyManager }
63. class TestActivity : AppCompatActivity(), ViewContainer { var testDependencyManager: DependencyManager? = null override val dependencyManager: DependencyManager by lazy { testDependencyManager!! } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val view = LinearLayout(this) view.id = 1 setContentView(view) } fun showFragment(fragment: Fragment) { supportFragmentManager .beginTransaction() .replace(1, fragment) .commit() } }
64. class TestActivity : AppCompatActivity(), ViewContainer { var testDependencyManager: DependencyManager? = null override val dependencyManager: DependencyManager by lazy { testDependencyManager!! } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val view = LinearLayout(this) view.id = 1 setContentView(view) } fun showFragment(fragment: Fragment) { supportFragmentManager .beginTransaction() .replace(1, fragment) .commit() } }
65. @RunWith(AndroidJUnit4::class) class ConferenceComponentTest { @get:Rule val rule: ActivityTestRule<TestActivity> = ActivityTestRule(TestActivity::class.java) @Test fun `Given a registered conference When conference screen appears Then show conference name`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val json = """ { "id": "1", "name": "Droidcon" } """ server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val stateMachine = ConferenceStateMachine(OkHttpConferenceGateway(baseUrl, OkHttpClient()), FakeDispatcher()) stateMachine.start() rule.activity.testDependencyManager = FakeDependencyManager(stateMachine, FakeDispatcher()) rule.activity.showFragment(ConferenceFragment()) onView(withId(R.id.conferenceName)).check(matches(ViewMatchers.withText("Droidcon"))) server.shutdown() } }
66. Arrange
67. @RunWith(AndroidJUnit4::class) class ConferenceComponentTest { @get:Rule val rule: ActivityTestRule<TestActivity> = ActivityTestRule(TestActivity::class.java) @Test fun `Given a registered conference When conference screen appears Then show conference name`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val json = """ { "id": "1", "name": "Droidcon" } """ server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val stateMachine = ConferenceStateMachine(OkHttpConferenceGateway(baseUrl, OkHttpClient()), FakeDispatcher()) stateMachine.start() rule.activity.testDependencyManager = FakeDependencyManager(stateMachine, FakeDispatcher()) rule.activity.showFragment(ConferenceFragment()) onView(withId(R.id.conferenceName)).check(matches(ViewMatchers.withText("Droidcon"))) server.shutdown() } }
68. Act
69. @RunWith(AndroidJUnit4::class) class ConferenceComponentTest { @get:Rule val rule: ActivityTestRule<TestActivity> = ActivityTestRule(TestActivity::class.java) @Test fun `Given a registered conference When conference screen appears Then show conference name`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val json = """ { "id": "1", "name": "Droidcon" } """ server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val stateMachine = ConferenceStateMachine(OkHttpConferenceGateway(baseUrl, OkHttpClient()), FakeDispatcher()) stateMachine.start() rule.activity.testDependencyManager = FakeDependencyManager(stateMachine, FakeDispatcher()) rule.activity.showFragment(ConferenceFragment()) onView(withId(R.id.conferenceName)).check(matches(ViewMatchers.withText("Droidcon"))) server.shutdown() } }
70. Assert
71. @RunWith(AndroidJUnit4::class) class ConferenceComponentTest { @get:Rule val rule: ActivityTestRule<TestActivity> = ActivityTestRule(TestActivity::class.java) @Test fun `Given a registered conference When conference screen appears Then show conference name`() { val server = MockWebServer() server.start() val baseUrl = server.url("/").toString() val json = """ { "id": "1", "name": "Droidcon" } """ server.enqueue(MockResponse().setResponseCode(200).setBody(json)) val stateMachine = ConferenceStateMachine(OkHttpConferenceGateway(baseUrl, OkHttpClient()), FakeDispatcher()) stateMachine.start() rule.activity.testDependencyManager = FakeDependencyManager(stateMachine, FakeDispatcher()) rule.activity.showFragment(ConferenceFragment()) onView(withId(R.id.conferenceName)).check(matches(ViewMatchers.withText("Droidcon"))) server.shutdown() } }
72. End-to-End Tests Domain Data Presentation DB External Service Android SDK
73. Arrange
74. Act
75. @RunWith(AndroidJUnit4::class) class ConferenceEndToEndTest { @get:Rule val rule: ActivityTestRule<MainActivity> = ActivityTestRule(MainActivity::class.java, true, false) @Test fun givenRegisteredConferenceWhenApplicationStartsStartShowConferenceName() { rule.launchActivity(Intent()) Thread.sleep(2000) onView(ViewMatchers.withId(R.id.conferenceName)).check(matches(withText("Droidcon"))) } }
76. Assert
77. @RunWith(AndroidJUnit4::class) class ConferenceEndToEndTest { @get:Rule val rule: ActivityTestRule<MainActivity> = ActivityTestRule(MainActivity::class.java, true, false) @Test fun givenRegisteredConferenceWhenApplicationStartsStartShowConferenceName() { rule.launchActivity(Intent()) Thread.sleep(2000) onView(ViewMatchers.withId(R.id.conferenceName)).check(matches(withText("Droidcon"))) } }
78. Unit Tests Integration Tests Component Tests End-to-End Tests Domain Data Fake DB Fake External Service Presentation Fake GUI DB External Service Android SDK
79. Reference • The Clean Architecture - Robert Martin (http://blog.cleancoder.com/uncle-bob/2012/08/13/the-clean-architecture.html) • Test Double - Martin Fowler (https://martinfowler.com/bliki/TestDouble.html) • Testing Strategies in a Microservices Architecture - Martin Fowler (https://martinfowler.com/articles/microservice-testing/#conclusion-summary) • Managing State with RxJava - Jake Wharton (https://www.youtube.com/watch?v=0IKHxjkgop4) • Android Testing Strategy - Marcelo Benites (https://engineering.talkdesk.com/android-testing-strategy-73269539c13d)
80. https://github.com/marcelorbenites/android-testing-strategy