Android Architecture Components - A Testable Approach to Android Development

Developing Android Apps has notoriously been a difficult task. Previously, Google refrained from giving advice as to how you should go about architecting your Android applications and it has been “left it up to the reader” to decide how. This lead to apps having a lot of bloat in their activities and being really difficult to test. This has now changed since Google I/O 2017 where the new Android Architecture components were introduced. The libraries aim to make developing and maintaining your Android apps a lot easier. In this presentation, Rebecca will present the components and dive into detail around the different types of tests you should write (and where) for your newly architected Android application.

Rebecca Franks is an Android Engineer at Over, currently building the Android version of the already popular photo editing iOS app. She is a Google Developer Expert for Android and she enjoys public speaking by frequently speaking at conferences and local meetups. Her blog has been featured multiple times on Android Weekly and she loves travelling the world.

1. @riggaroo Android Architecture Components A Testable Approach to Android Development Rebecca Franks
2. HELLO! I am Rebecca Franks Android Developer Google Developer Expert @riggaroo
3. What are the Android Architecture Components? Powerful APIs that are testable " Improve app quality ✅ Address common issues Best practice guidelines %
4. @riggaroo Components - Room - ViewModels - LiveData * - Lifecycle * - Paging Library * - …
5. Architecting an App
6. bit.ly/android-arch bit.ly/android-arch-kotlin
7. MVVM Model, View, ViewModel
8. MVVM View ViewModel Model
9. View ViewModel Model Retrofit API Room Database Web Service SQLite MVVM
10. View ViewModel Model Retrofit API Room Database Web Service SQLite MVVM
11. Room - SQLite Object Mapper
12. Creating an Entity @Entity(tableName = TABLE_NAME) public class Event { @PrimaryKey(autoGenerate = true) private int id; private String name; private LocalDateTime date; public int getId() { return id; } public String getName() { return name; } public LocalDateTime getDate() { return date; } }
13. Creating a DAO @Dao public interface EventDao { @Insert(onConflict = OnConflictStrategy.REPLACE) void addEvent(Event event); @Query("SELECT * FROM " + Event.TABLE_NAME + " WHERE " + Event.DATE_FIELD + " > :minDate") LiveData<List<Event>> getEvents(LocalDateTime minDate); }
14. Creating a Database @Database(entities = {Event.class}, version = 1) public abstract class EventDatabase extends RoomDatabase { public abstract EventDao eventDao(); }
15. Create an instance of the DB @Provides @Singleton EventDatabase providesEventDatabase(CountdownApplication context) { return Room.databaseBuilder(context, EventDatabase.class, “event.db").build(); }
16. Model
17. View ViewModel Model Retrofit API Room Database Web Service SQLite MVVM
18. Model Model layer follows Repository pattern ie EventRepository, LoginRepository MVVM - Model
19. Repository
20. Repository Business Logic, Caching Plain object No Android Dependencies
21. public class EventRepositoryImpl implements EventRepository { @Inject EventDao eventDao; public EventRepositoryImpl(EventDao eventDao) { this.eventDao = eventDao; } @Override public Completable addEvent(Event event) { if (event == null){ return Completable.error(new IllegalArgumentException("Event cannot be null")); } return Completable.fromAction(() -> eventDao.addEvent(event)); } }
22. public class EventRepositoryImpl implements EventRepository { @Inject EventDao eventDao; public EventRepositoryImpl(EventDao eventDao) { this.eventDao = eventDao; } @Override public Completable addEvent(Event event) { if (event == null){ return Completable.error(new IllegalArgumentException("Event cannot be null")); } return Completable.fromAction(() -> eventDao.addEvent(event)); } } Completable is used when the Observable has to do some task without emitting a value.
23. ViewModel
24. View ViewModel Model Retrofit API Room Database Web Service SQLite MVVM
25. ViewModel AddEventViewModel, EventListViewModel MVVM - ViewModel
26. What is a ViewModel? - The VM in MVVM architecture - Store & manage UI-related data - Data survives config changes - No leaks
27. public class AddEventViewModel extends ViewModel { @Inject EventRepository eventRepository; private String eventName; private String eventDescription; private LocalDateTime eventDateTime ; @Inject AddEventViewModel() { eventDateTime = LocalDateTime.now(); } void addEvent() { Event event = new Event(0, eventName, eventDescription, eventDateTime); eventRepository.addEvent(event).observeOn(AndroidSchedulers.mainThread()) .subscribeOn(Schedulers.io()) .subscribe(new CompletableObserver() { @Override public void onSubscribe(Disposable d) { } Creating your ViewModel
28. @Inject AddEventViewModel() { eventDateTime = LocalDateTime.now(); } void addEvent() { Event event = new Event(0, eventName, eventDescription, eventDateTime); eventRepository.addEvent(event).observeOn(AndroidSchedulers.mainThread()) .subscribeOn(Schedulers.io()) .subscribe(new CompletableObserver() { @Override public void onSubscribe(Disposable d) { } @Override public void onComplete() { Log.d(TAG, ”onComplete - successfully added event"); } @Override public void onError(Throwable e) { Log.d(TAG, e, "onError - add:"); } }); }
29. @Inject AddEventViewModel() { eventDateTime = LocalDateTime.now(); } void addEvent() { Event event = new Event(0, eventName, eventDescription, eventDateTime); eventRepository.addEvent(event).observeOn(AndroidSchedulers.mainThread()) .subscribeOn(Schedulers.io()) .subscribe(new CompletableObserver() { @Override public void onSubscribe(Disposable d) { } @Override public void onComplete() { Log.d(TAG, ”onComplete - successfully added event"); } @Override public void onError(Throwable e) { Log.d(TAG, e, "onError - add:"); } }); }
30. View
31. View ViewModel Model Retrofit API Room Database Web Service SQLite MVVM
32. View AddEventFragment, EventListFragment MVVM - View
33. public class AddEventFragment extends Fragment { private Button buttonAddEvent; private AddEventViewModel addEventViewModel; @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_add_event, container, false); //.. setupClickListeners(); setupViewModel(); return view; } private void setupViewModel() { addEventViewModel = ViewModelProviders.of(this).get(AddEventViewModel.class); } private void setupClickListeners() { buttonAddEvent.setOnClickListener(v -> { addEventViewModel.addEvent(); getActivity().finish(); }); } }
34. public class AddEventFragment extends Fragment { private Button buttonAddEvent; private AddEventViewModel addEventViewModel; @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_add_event, container, false); //.. setupClickListeners(); setupViewModel(); return view; } private void setupViewModel() { addEventViewModel = ViewModelProviders.of(this).get(AddEventViewModel.class); } private void setupClickListeners() { buttonAddEvent.setOnClickListener(v -> { addEventViewModel.addEvent(); getActivity().finish(); }); } }
35. public class AddEventFragment extends Fragment { private Button buttonAddEvent; private AddEventViewModel addEventViewModel; @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_add_event, container, false); //.. setupClickListeners(); setupViewModel(); return view; } private void setupViewModel() { addEventViewModel = ViewModelProviders.of(this).get(AddEventViewModel.class); } private void setupClickListeners() { buttonAddEvent.setOnClickListener(v -> { addEventViewModel.addEvent(); getActivity().finish(); }); } }
36. public class AddEventFragment extends Fragment { private Button buttonAddEvent; private AddEventViewModel addEventViewModel; @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_add_event, container, false); //.. setupClickListeners(); setupViewModel(); return view; } private void setupViewModel() { addEventViewModel = ViewModelProviders.of(this).get(AddEventViewModel.class); } private void setupClickListeners() { buttonAddEvent.setOnClickListener(v -> { addEventViewModel.addEvent(); getActivity().finish(); }); } }
37. Demo
39. Let’s chat about tests…
41. View ViewModel Model Retrofit API Room Database Web Service SQLite JUnit tests MVVM
42. View ViewModel Model Retrofit API Room Database Web Service SQLite Instrumentation Tests MVVM
43. Abstract out Android Logic as much as possible. Write plenty of JUnit Tests, not as many UI Tests
45. @riggaroo JUnit Tests - Run on JVM - No Android Dependencies - Use Mockito - mock out everything but current class under test
46. @riggaroo Instrumentation Tests - Two Types: - Android Unit Test - Use Android dependencies - No UI - UI Test - Use Espresso - Physical clicks on device - Hardly any mocking (maybe HTTP responses)
47. Testing Database Queries
48. View ViewModel Model Retrofit API Room Database Web Service SQLite Testing Room
49. @RunWith(AndroidJUnit4.class) public class EventDaoTest { EventDao eventDao; EventDatabase eventDatabase; @Before public void setup() { eventDatabase = Room.inMemoryDatabaseBuilder(InstrumentationRegistry.getContext(), EventDatabase.class).build(); eventDao = eventDatabase.eventDao(); } @Test public void addEvent_SuccessfullyAddsEvent() throws InterruptedException { Event event = generateEventTestData(0, "Wedding"); eventDao.addEvent(event); List<Event> eventRetrieved = getValue(eventDao.getEvents(LocalDateTime.now())); assertEquals(event.getName(), eventRetrieved.get(0).getName()); } }
50. @RunWith(AndroidJUnit4.class) public class EventDaoTest { EventDao eventDao; EventDatabase eventDatabase; @Before public void setup() { eventDatabase = Room.inMemoryDatabaseBuilder(InstrumentationRegistry.getContext(), EventDatabase.class).build(); eventDao = eventDatabase.eventDao(); } @Test public void addEvent_SuccessfullyAddsEvent() throws InterruptedException { Event event = generateEventTestData(0, "Wedding"); eventDao.addEvent(event); List<Event> eventRetrieved = getValue(eventDao.getEvents(LocalDateTime.now())); assertEquals(event.getName(), eventRetrieved.get(0).getName()); } }
51. @RunWith(AndroidJUnit4.class) public class EventDaoTest { EventDao eventDao; EventDatabase eventDatabase; @Before public void setup() { eventDatabase = Room.inMemoryDatabaseBuilder(InstrumentationRegistry.getContext(), EventDatabase.class).build(); eventDao = eventDatabase.eventDao(); } @Test public void addEvent_SuccessfullyAddsEvent() throws InterruptedException { Event event = generateEventTestData(0, "Wedding"); eventDao.addEvent(event); List<Event> eventRetrieved = getValue(eventDao.getEvents(LocalDateTime.now())); assertEquals(event.getName(), eventRetrieved.get(0).getName()); } }
52. @RunWith(AndroidJUnit4.class) public class EventDaoTest { EventDao eventDao; EventDatabase eventDatabase; @Before public void setup() { eventDatabase = Room.inMemoryDatabaseBuilder(InstrumentationRegistry.getContext(), EventDatabase.class).build(); eventDao = eventDatabase.eventDao(); } @Test public void addEvent_SuccessfullyAddsEvent() throws InterruptedException { Event event = generateEventTestData(0, "Wedding"); eventDao.addEvent(event); List<Event> eventRetrieved = getValue(eventDao.getEvents(LocalDateTime.now())); assertEquals(event.getName(), eventRetrieved.get(0).getName()); } }
53. Testing Models/ Repositories
54. View ViewModel Model Retrofit API Room Database Web Service SQLite Model Tests
55. public class EventRepositoryImplTest { @Mock private EventDao eventDao; @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule(); private EventRepository eventRepository; @Before public void setUp() { MockitoAnnotations.initMocks(this); eventRepository = new EventRepositoryImpl(eventDao); } @Test public void addEvent_TriggersDbAdd(){ Event event = FakeEventDataGenerator.getFakeEvent(); eventRepository.addEvent(event).test().onComplete(); verify(eventDao).addEvent(event); } }
56. public class EventRepositoryImplTest { @Mock private EventDao eventDao; @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule(); private EventRepository eventRepository; @Before public void setUp() { MockitoAnnotations.initMocks(this); eventRepository = new EventRepositoryImpl(eventDao); } @Test public void addEvent_TriggersDbAdd(){ Event event = FakeEventDataGenerator.getFakeEvent(); eventRepository.addEvent(event).test().onComplete(); verify(eventDao).addEvent(event); } }
57. public class EventRepositoryImplTest { @Mock private EventDao eventDao; @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule(); private EventRepository eventRepository; @Before public void setUp() { MockitoAnnotations.initMocks(this); eventRepository = new EventRepositoryImpl(eventDao); } @Test public void addEvent_TriggersDbAdd(){ Event event = FakeEventDataGenerator.getFakeEvent(); eventRepository.addEvent(event).test().onComplete(); verify(eventDao).addEvent(event); } }
58. Testing ViewModels
59. View ViewModel Model Retrofit API Room Database Web Service SQLite View Model Tests
60. public class AddEventViewModelTest { AddEventViewModel addEventViewModel; @Mock EventRepository eventRepository; @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule(); @Before public void setup() { MockitoAnnotations.initMocks(this); addEventViewModel = new AddEventViewModel(); addEventViewModel.eventRepository = eventRepository; } @Test public void addEvent() { when(eventRepository.addEvent(any())).thenReturn(Completable.complete()); addEventViewModel.addEvent(); verify(eventRepository).addEvent(any()); }
61. public class AddEventViewModelTest { AddEventViewModel addEventViewModel; @Mock EventRepository eventRepository; @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule(); @Before public void setup() { MockitoAnnotations.initMocks(this); addEventViewModel = new AddEventViewModel(); addEventViewModel.eventRepository = eventRepository; } @Test public void addEvent() { when(eventRepository.addEvent(any())).thenReturn(Completable.complete()); addEventViewModel.addEvent(); verify(eventRepository).addEvent(any()); }
62. public class AddEventViewModelTest { AddEventViewModel addEventViewModel; @Mock EventRepository eventRepository; @Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule(); @Before public void setup() { MockitoAnnotations.initMocks(this); addEventViewModel = new AddEventViewModel(); addEventViewModel.eventRepository = eventRepository; } @Test public void addEvent() { when(eventRepository.addEvent(any())).thenReturn(Completable.complete()); addEventViewModel.addEvent(); verify(eventRepository).addEvent(any()); }
63. View Tests ☕
64. View ViewModel Model Retrofit API Room Database Web Service SQLite View Tests
65. Espresso Basic Formula
66. @RunWith(AndroidJUnit4.class) public class AddEventFragmentTest { @Rule public ActivityTestRule<AddEventActivity> activityTestRule = new ActivityTestRule<>(AddEventActivity.class, true, true); private AddEventViewModel addEventViewModel; @Before public void setup(){ addEventViewModel = mock(AddEventViewModel.class); //.. } @Test public void addEvent(){ when(addEventViewModel.getEventDateTime()).thenReturn(LocalDateTime.now()); onView(withId(R.id.edit_text_title)).perform(typeText("Christmas Day"), closeSoftKeyboard()); onView(withId(R.id.button_set_date)).perform(click()); onView(withText("OK")).perform(scrollTo(), click()); onView(withId(R.id.button_add)).perform(click());
67. public ActivityTestRule<AddEventActivity> activityTestRule = new ActivityTestRule<>(AddEventActivity.class, true, true); private AddEventViewModel addEventViewModel; @Before public void setup(){ addEventViewModel = mock(AddEventViewModel.class); //.. } @Test public void addEvent(){ when(addEventViewModel.getEventDateTime()).thenReturn(LocalDateTime.now()); onView(withId(R.id.edit_text_title)).perform(typeText("Christmas Day"), closeSoftKeyboard()); onView(withId(R.id.button_set_date)).perform(click()); onView(withText("OK")).perform(scrollTo(), click()); onView(withId(R.id.button_add)).perform(click()); } }
68. public ActivityTestRule<AddEventActivity> activityTestRule = new ActivityTestRule<>(AddEventActivity.class, true, true); private AddEventViewModel addEventViewModel; @Before public void setup(){ addEventViewModel = mock(AddEventViewModel.class); //.. } @Test public void addEvent(){ when(addEventViewModel.getEventDateTime()).thenReturn(LocalDateTime.now()); onView(withId(R.id.edit_text_title)).perform(typeText("Christmas Day"), closeSoftKeyboard()); onView(withId(R.id.button_set_date)).perform(click()); onView(withText("OK")).perform(scrollTo(), click()); onView(withId(R.id.button_add)).perform(click()); } }
69. public ActivityTestRule<AddEventActivity> activityTestRule = new ActivityTestRule<>(AddEventActivity.class, true, true); private AddEventViewModel addEventViewModel; @Before public void setup(){ addEventViewModel = mock(AddEventViewModel.class); //.. } @Test public void addEvent(){ when(addEventViewModel.getEventDateTime()).thenReturn(LocalDateTime.now()); onView(withId(R.id.edit_text_title)).perform(typeText("Christmas Day"), closeSoftKeyboard()); onView(withId(R.id.button_set_date)).perform(click()); onView(withText("OK")).perform(scrollTo(), click()); onView(withId(R.id.button_add)).perform(click()); } }
70. Running UI Tests
72. What about Android classes or static methods?
73. JUnit tests View ViewModel Repository ResourceProvider SharedPrefProvider MVVM
74. Android Unit tests View ViewModel Repository ResourceProvider SharedPrefProvider MVVM
75. public class ResourceProvider { private final Context context; public ResourceProvider(Context context){ this.context = context; } public String getString(Integer resId){ return context.getString(resId); } }
77. Summary Encourages clean code ( UI Tests using Espresso Less memory leaks and bugs Simplifies code
78. @riggaroo Thank you! developer.android.com/arch Rebecca Franks @riggaroo