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Testing Android apps based on Dagger and RxJava

Fabio Collini
Fabio Collini

The document outlines the testing of Android applications using Dagger and RxJava, discussing various testing frameworks and methodologies such as Mockito and Espresso. Key components include the architecture involving activities, presenters, and interactors, along with examples of unit and integration tests. It also emphasizes the use of dependency injection with Dagger in unit tests, showcasing code snippets and strategies for effective testing.

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Testing Android apps based on Dagger and RxJava Fabio Collini droidcon Italy April 2017
2 Ego slide @fabioCollini linkedin.com/in/fabiocollini github.com/fabioCollini medium.com/@fabioCollini codingjam.it
3 Agenda 1. Dagger 2. Testing 3. Mockito 4. Espresso 5. DaggerMock 6. RxJava
4 github.com/fabioCollini/TestingDaggerRxJava
5 Activity Presenter Interactor Retrofit Service Rx Rx @Singleton @Provides @Singleton @Provides @Provides@Inject
public interface StackOverflowService {
 
 @GET("/users") 
 Single<List<User>> getTopUsers();
 
 @GET("/users/{userId}/badges") 
 Single<List<Badge>> getBadges(@Path("userId") int userId);
 } Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }
 
 public Single<List<UserStats>> loadUsers() {
 //...
 }
 } Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
public class UserListPresenter {b
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }onCreate
 
 public void reloadUserList() {
 userInteractor .loadUsers()
 //...
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }showError
 }end Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
public class UserListActivity extends AppCompatActivity {b
 
 @Inject UserListPresenter presenter;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) { //... ((MyApp) getApplicationContext()).getComponent()
 .userListComponent(new UserListModule(this)).inject(this);
 presenter.reloadUserList();
 }onCreate
 
 public void updateText(String s) { //... }updateText
 
 public void showError(Throwable t) { //... }showError
 }end Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
10 @Singleton
 @Component(modules = {UserInteractorModule.class, StackOverflowServiceModule.class})
 public interface ApplicationComponent {
 UserListComponent userListComponent(UserListModule module);
 } @Module
 public class UserInteractorModule {
 @Provides @Singleton public UserInteractor provideInteractor() {
 //...
 }
 } @Module
 public class StackOverflowServiceModule {
 @Provides @Singleton public StackOverflowService provideService() {
 //...
 }
 } @Subcomponent(modules = UserListModule.class)
 public interface UserListComponent {
 void inject(UserListActivity activity);
 } @Module
 public class UserListModule {
 @Provides public UserListPresenter providePresenter() {
 //...
 }
 }
Activity Presenter Interactor Retrofit Service UnitUnitUnit Integration UI UI UI E2E Espresso JVM
12 Return Of Investment Net profit Investment
13
14
15
16 Unit E2E Integration Manual tests Testing pyramid
17 Integrated tests are a scam a self-replicating virus that threatens to infect your code base, your project, and your team with endless pain and suffering. J. B. Rainsberger
18 Mockito tips
public class MyTest {
 
 Collaborator1 collaborator1;
 
 Collaborator2 collaborator2;
 
 ObjectUnderTest objectUnderTest;
 
 @Before
 public void setUp() {
 collaborator1 = Mockito.mock(Collaborator1.class);
 collaborator2 = Mockito.mock(Collaborator2.class);
 objectUnderTest = new ObjectUnderTest( collaborator1, collaborator2);
 }setUp
 
 @Test
 public void myTestMethod() {
 //Arrange
 when(collaborator1.provideValue()).thenReturn(2);
 //Act
 objectUnderTest.execute();
 //Assert
 verify(collaborator2).printValue(10);
 assertThat(objectUnderTest.getValue()).isEqualTo(10);
 }_
 }__
public class MyTest {
 
 @Rule public MockitoRule mockitoRule = MockitoJUnit.rule();
 
 @Mock Collaborator1 collaborator1;
 
 @Mock Collaborator2 collaborator2;
 
 @InjectMocks ObjectUnderTest objectUnderTest;
 
 @Test
 public void myTestMethod() {
 //Arrange
 when(collaborator1.provideValue()).thenReturn(2);
 //Act
 objectUnderTest.execute();
 //Assert
 verify(collaborator2).printValue(10);
 assertThat(objectUnderTest.getValue()).isEqualTo(10);
 }_
 }__
package org.mockito.configuration;
 //... public class MockitoConfiguration extends DefaultMockitoConfiguration {
 public Answer<Object> getDefaultAnswer() {
 return new ReturnsEmptyValues() {
 @Override
 public Object answer(InvocationOnMock inv) {
 Class<?> type = inv.getMethod().getReturnType();
 if (type.isAssignableFrom(Observable.class)) {
 return Observable.error(createException(inv));
 } else if (type.isAssignableFrom(Single.class)) {
 return Single.error(createException(inv));
 } else {
 return super.answer(inv);
 }
 }
 };
 }
 
 private RuntimeException createException(
 InvocationOnMock invocation) {
 String s = invocation.toString();
 return new RuntimeException(
 "No mock defined for invocation " + s);
 }
 }
Espresso Activity Presenter Interactor Retrofit Service
public class UserListPresenter {
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }
 
 public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }
 } Activity Presenter Interactor Retrofit Service
@Singleton
 @Component(modules = {
 TestUserInteractorModule.class,
 StackOverflowServiceModule.class
 })
 public interface TestApplicationComponent
 extends ApplicationComponent {
 void inject(UserListActivityTest userListActivityTest);
 } Activity Presenter Interactor Retrofit Service @Module
 public class TestUserInteractorModule {
 @Provides @Singleton
 public UserInteractor provideUserInteractor() {
 return Mockito.mock(UserInteractor.class);
 }
 }
public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service
public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service ArrangeActAssert
Activity Presenter Interactor Retrofit Service public class UserListPresenter {
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }___
 
 public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }__
 }_
Scheduler asyncTaskScheduler =
 Schedulers.from(AsyncTask.THREAD_POOL_EXECUTOR);
public class AsyncTaskSchedulerRule implements TestRule {
 
 private final Scheduler asyncTaskScheduler =
 Schedulers.from(AsyncTask.THREAD_POOL_EXECUTOR);
 
 @Override
 public Statement apply(final Statement base, Description d) {
 return new Statement() {
 @Override
 public void evaluate() throws Throwable {
 RxJavaPlugins.setIoSchedulerHandler(
 scheduler -> asyncTaskScheduler);
 RxJavaPlugins.setComputationSchedulerHandler(
 scheduler -> asyncTaskScheduler);
 RxJavaPlugins.setNewThreadSchedulerHandler(
 scheduler -> asyncTaskScheduler);
 
 try {
 base.evaluate();
 } finally {
 RxJavaPlugins.reset();
 }
 }
 };
 }
 }
public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 @Rule public AsyncTaskSchedulerRule asyncTaskSchedulerRule = new AsyncTaskSchedulerRule(); 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service ArrangeActAssert
public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 @Rule public AsyncTaskSchedulerRule asyncTaskSchedulerRule = new AsyncTaskSchedulerRule(); 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service ArrangeActAssert
@Singleton
 @Component(modules = {
 TestUserInteractorModule.class,
 StackOverflowServiceModule.class
 })
 public interface TestApplicationComponent
 extends ApplicationComponent {
 void inject(UserListActivityTest userListActivityTest);
 }_ Activity Presenter Interactor Retrofit Service @Module
 public class TestUserInteractorModule {
 @Provides @Singleton
 public UserInteractor provideUserInteractor() {
 return Mockito.mock(UserInteractor.class);
 }
 } //...
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }__ //...
Activity Presenter Interactor Retrofit Service //... @Rule public MockitoRule mockitoRule = MockitoJUnit.rule();
 
 @Mock UserInteractor userInteractor;
 
 @Before public void setUp() {
 ApplicationComponent component =
 DaggerApplicationComponent.builder()
 .userInteractorModule(new UserInteractorModule() {
 @Override
 public UserInteractor provideUserInteractor(
 StackOverflowService service) {
 return userInteractor;
 }___
 })
 .build();
 getAppFromInstrumentation().setComponent(component);
 }__ //...
34
//... @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(
 ApplicationComponent.class,
 new UserInteractorModule()
 ).set(component ->
 getAppFromInstrumentation().setComponent(component));
 
 @Mock UserInteractor userInteractor; //... Activity Presenter Interactor Retrofit Service
Activity Presenter Interactor Retrofit Service public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Rule public AsyncTaskSchedulerRule asyncTaskSchedulerRule = new AsyncTaskSchedulerRule(); 
 @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(
 ApplicationComponent.class,
 new UserInteractorModule()
 ).set(component ->
 getAppFromInstrumentation().setComponent(component));
 
 @Mock UserInteractor userInteractor;
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }
 }
static <T> T createSubclass(final T module, final Map<Class, Object> testFields) {
 return (T) Mockito.mock(module.getClass(), new Answer() {
 @Override public Object answer(InvocationOnMock invocation) throws Throwable {
 Method method = invocation.getMethod();
 Object obj = testFields.get(method.getReturnType());
 if (obj != null) {
 return obj;
 } else {
 return method.invoke(module, invocation.getArguments());
 }
 }
 });
 } DaggerMock internals
Activity Presenter Interactor Retrofit Service @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(
 ApplicationComponent.class,
 new UserInteractorModule()
 ).set(component ->
 getAppFromInstrumentation().setComponent(component));
Activity Presenter Interactor Retrofit Service public class MyDaggerMockRule
 extends DaggerMockRule<ApplicationComponent> {
 
 public MyDaggerMockRule() {
 super(
 ApplicationComponent.class,
 new UserInteractorModule()
 );
 set(component ->
 getAppFromInstrumentation().setComponent(component)); 
 providesMock(UserInteractor.class, userInteractor ->
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList())
 );
 }__
 }_
Espresso Activity Presenter Interactor Retrofit Service
41 public class MockPresenterTest {
 
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Rule public MyDaggerMockRule daggerMockRule =
 new MyDaggerMockRule();
 
 @Mock UserListPresenter presenter;
 
 @Test
 public void testOnCreate() {
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText("")));
 
 verify(presenter).reloadUserList();
 }
 } Activity Presenter Interactor Retrofit Service
1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code
Activity Presenter Interactor Retrofit Service JVM
public class UserListPresenter {
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }
 
 public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }_
 } Activity Presenter Interactor Retrofit Service
Activity Presenter Interactor Retrofit Service public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }_

public class UserListPresenterTest {
 
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectMocks UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 presenter.reloadUserList();
 verify(activity).updateText(anyString());
 }_
 }__ Activity Presenter Interactor Retrofit Service
47
48
public class TrampolineSchedulerRule implements TestRule {
 
 @Override
 public Statement apply(final Statement base, Description d) {
 return new Statement() {
 @Override
 public void evaluate() throws Throwable {
 RxJavaPlugins.setIoSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 RxJavaPlugins.setComputationSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 RxJavaPlugins.setNewThreadSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 RxAndroidPlugins.setInitMainThreadSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 
 try {
 base.evaluate();
 } finally {
 RxJavaPlugins.reset();
 RxAndroidPlugins.reset();
 }
 }
 };
 }
 }
Activity Presenter Interactor Retrofit Service public class UserListPresenterTest {
 
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 @Rule public TrampolineSchedulerRule schedulerRule =
 new TrampolineSchedulerRule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectMocks UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 presenter.reloadUserList();
 
 verify(activity).updateText(
 "50 user1 - badge1nn30 user2 - badge2, badge3");
 }__
 }_
Activity Presenter Interactor Retrofit Service public class UserListPresenterTest {
 
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 @Rule public TrampolineSchedulerRule schedulerRule =
 new TrampolineSchedulerRule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectMocks UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 presenter.reloadUserList();
 
 verify(activity).updateText(
 "50 user1 - badge1nn30 user2 - badge2, badge3");
 }__
 }_
Activity Presenter Interactor Retrofit Service public class UserListPresenterTest {
 
 @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(ApplicationComponent.class, new UserInteractorModule());
 
 @Rule public TrampolineSchedulerRule schedulerRule = 
 new TrampolineSchedulerRule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectFromComponent(UserListActivity.class) 
 UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 presenter.reloadUserList();
 
 verify(activity).updateText(
 "50 user1 - badge1nn30 user2 - badge2, badge3");
 }__
 }_
1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code trampoline scheduler
Activity Presenter Interactor Retrofit Service JVM
Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }
 }
56
public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_ Activity Presenter Interactor Retrofit Service
1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code trampoline scheduler blockingGet
Activity Presenter Interactor Retrofit Service public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
Activity Presenter Interactor Retrofit Service public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id()) .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
Activity Presenter Interactor Retrofit Service public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_
Activity Presenter Interactor Retrofit Service public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_
Activity Presenter Interactor Retrofit Service public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 @Rule public TrampolineSchedulerRule schedulerRule =
 new TrampolineSchedulerRule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_
Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 userInteractor.loadUsers()
 .test()
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 userInteractor.loadUsers()
 .test()
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 userInteractor.loadUsers()
 .test()
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
public class TestSchedulerRule implements TestRule {
 private final TestScheduler testScheduler = new TestScheduler();
 
 public TestScheduler getTestScheduler() {
 return testScheduler;
 }
 
 @Override
 public Statement apply(final Statement base, Description d) {
 return new Statement() {
 @Override
 public void evaluate() throws Throwable {
 RxJavaPlugins.setIoSchedulerHandler(
 scheduler -> testScheduler);
 RxJavaPlugins.setComputationSchedulerHandler(
 scheduler -> testScheduler);
 RxJavaPlugins.setNewThreadSchedulerHandler(
 scheduler -> testScheduler);
 RxAndroidPlugins.setMainThreadSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 
 try {
 base.evaluate();
 } finally {
 RxJavaPlugins.reset();
 RxAndroidPlugins.reset();
 }
 }
 };
 }
 }
Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 )); Activity Presenter Interactor Retrofit Service
Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__
Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__
public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__ Activity Presenter Interactor Retrofit Service
Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .concatMapEager(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__
Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(l ->
 assertThat(l).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(l ->
 assertThat(l).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 )); Activity Presenter Interactor Retrofit Service
1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code trampoline scheduler blockingGet TestScheduler & TestObserver
77 Wrapping up 1.JVM tests isolate failures and are fast and reliable 2.Using DaggerMock testing boilerplate code can be reduced 3.RxJava asynchronous code can be tested using TestObserver and TestScheduler
78 Links github.com/fabioCollini/TestingDaggerRxJava github.com/fabioCollini/DaggerMock joel-costigliola.github.io/assertj medium.com/@fabioCollini/testing-asynchronous-rxjava-code-using- mockito-8ad831a16877 medium.com/@fabioCollini/android-testing-using-dagger-2-mockito-and-a-custom-junit- rule-c8487ed01b56 testing.googleblog.com/2015/04/just-say-no-to-more-end-to-end-tests.html blog.thecodewhisperer.com/permalink/clearing-up-the-integrated-tests-scam collectiveidea.com/blog/archives/2016/10/13/retrofitting-espresso/ medium.com/@peter.tackage/an-alternative-to-rxandroidplugins-and-rxjavaplugins- scheduler-injection-9831bbc3dfaf artemzin.com/blog/jfyi-overriding-module-classes-with-dagger2/
Thanks for your attention! Questions?

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Testing Android apps based on Dagger and RxJava

  • 1. Testing Android apps based on Dagger and RxJava Fabio Collini droidcon Italy April 2017
  • 3. 3 Agenda 1. Dagger 2. Testing 3. Mockito 4. Espresso 5. DaggerMock 6. RxJava
  • 6. public interface StackOverflowService {
 
 @GET("/users") 
 Single<List<User>> getTopUsers();
 
 @GET("/users/{userId}/badges") 
 Single<List<Badge>> getBadges(@Path("userId") int userId);
 } Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
  • 7. public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }
 
 public Single<List<UserStats>> loadUsers() {
 //...
 }
 } Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
  • 8. public class UserListPresenter {b
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }onCreate
 
 public void reloadUserList() {
 userInteractor .loadUsers()
 //...
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }showError
 }end Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
  • 9. public class UserListActivity extends AppCompatActivity {b
 
 @Inject UserListPresenter presenter;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) { //... ((MyApp) getApplicationContext()).getComponent()
 .userListComponent(new UserListModule(this)).inject(this);
 presenter.reloadUserList();
 }onCreate
 
 public void updateText(String s) { //... }updateText
 
 public void showError(Throwable t) { //... }showError
 }end Activity Presenter Interactor Retrofit Service Rx Rx SingletonSingleton
  • 10. 10 @Singleton
 @Component(modules = {UserInteractorModule.class, StackOverflowServiceModule.class})
 public interface ApplicationComponent {
 UserListComponent userListComponent(UserListModule module);
 } @Module
 public class UserInteractorModule {
 @Provides @Singleton public UserInteractor provideInteractor() {
 //...
 }
 } @Module
 public class StackOverflowServiceModule {
 @Provides @Singleton public StackOverflowService provideService() {
 //...
 }
 } @Subcomponent(modules = UserListModule.class)
 public interface UserListComponent {
 void inject(UserListActivity activity);
 } @Module
 public class UserListModule {
 @Provides public UserListPresenter providePresenter() {
 //...
 }
 }
  • 12. 12 Return Of Investment Net profit Investment
  • 13. 13
  • 14. 14
  • 15. 15
  • 17. 17 Integrated tests are a scam a self-replicating virus that threatens to infect your code base, your project, and your team with endless pain and suffering. J. B. Rainsberger
  • 19. public class MyTest {
 
 Collaborator1 collaborator1;
 
 Collaborator2 collaborator2;
 
 ObjectUnderTest objectUnderTest;
 
 @Before
 public void setUp() {
 collaborator1 = Mockito.mock(Collaborator1.class);
 collaborator2 = Mockito.mock(Collaborator2.class);
 objectUnderTest = new ObjectUnderTest( collaborator1, collaborator2);
 }setUp
 
 @Test
 public void myTestMethod() {
 //Arrange
 when(collaborator1.provideValue()).thenReturn(2);
 //Act
 objectUnderTest.execute();
 //Assert
 verify(collaborator2).printValue(10);
 assertThat(objectUnderTest.getValue()).isEqualTo(10);
 }_
 }__
  • 20. public class MyTest {
 
 @Rule public MockitoRule mockitoRule = MockitoJUnit.rule();
 
 @Mock Collaborator1 collaborator1;
 
 @Mock Collaborator2 collaborator2;
 
 @InjectMocks ObjectUnderTest objectUnderTest;
 
 @Test
 public void myTestMethod() {
 //Arrange
 when(collaborator1.provideValue()).thenReturn(2);
 //Act
 objectUnderTest.execute();
 //Assert
 verify(collaborator2).printValue(10);
 assertThat(objectUnderTest.getValue()).isEqualTo(10);
 }_
 }__
  • 21. package org.mockito.configuration;
 //... public class MockitoConfiguration extends DefaultMockitoConfiguration {
 public Answer<Object> getDefaultAnswer() {
 return new ReturnsEmptyValues() {
 @Override
 public Object answer(InvocationOnMock inv) {
 Class<?> type = inv.getMethod().getReturnType();
 if (type.isAssignableFrom(Observable.class)) {
 return Observable.error(createException(inv));
 } else if (type.isAssignableFrom(Single.class)) {
 return Single.error(createException(inv));
 } else {
 return super.answer(inv);
 }
 }
 };
 }
 
 private RuntimeException createException(
 InvocationOnMock invocation) {
 String s = invocation.toString();
 return new RuntimeException(
 "No mock defined for invocation " + s);
 }
 }
  • 23. public class UserListPresenter {
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }
 
 public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }
 } Activity Presenter Interactor Retrofit Service
  • 24. @Singleton
 @Component(modules = {
 TestUserInteractorModule.class,
 StackOverflowServiceModule.class
 })
 public interface TestApplicationComponent
 extends ApplicationComponent {
 void inject(UserListActivityTest userListActivityTest);
 } Activity Presenter Interactor Retrofit Service @Module
 public class TestUserInteractorModule {
 @Provides @Singleton
 public UserInteractor provideUserInteractor() {
 return Mockito.mock(UserInteractor.class);
 }
 }
  • 25. public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service
  • 26. public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service ArrangeActAssert
  • 27. Activity Presenter Interactor Retrofit Service public class UserListPresenter {
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }___
 
 public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }__
 }_
  • 29. public class AsyncTaskSchedulerRule implements TestRule {
 
 private final Scheduler asyncTaskScheduler =
 Schedulers.from(AsyncTask.THREAD_POOL_EXECUTOR);
 
 @Override
 public Statement apply(final Statement base, Description d) {
 return new Statement() {
 @Override
 public void evaluate() throws Throwable {
 RxJavaPlugins.setIoSchedulerHandler(
 scheduler -> asyncTaskScheduler);
 RxJavaPlugins.setComputationSchedulerHandler(
 scheduler -> asyncTaskScheduler);
 RxJavaPlugins.setNewThreadSchedulerHandler(
 scheduler -> asyncTaskScheduler);
 
 try {
 base.evaluate();
 } finally {
 RxJavaPlugins.reset();
 }
 }
 };
 }
 }
  • 30. public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 @Rule public AsyncTaskSchedulerRule asyncTaskSchedulerRule = new AsyncTaskSchedulerRule(); 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service ArrangeActAssert
  • 31. public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 @Rule public AsyncTaskSchedulerRule asyncTaskSchedulerRule = new AsyncTaskSchedulerRule(); 
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }A
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }B
 }C Activity Presenter Interactor Retrofit Service ArrangeActAssert
  • 32. @Singleton
 @Component(modules = {
 TestUserInteractorModule.class,
 StackOverflowServiceModule.class
 })
 public interface TestApplicationComponent
 extends ApplicationComponent {
 void inject(UserListActivityTest userListActivityTest);
 }_ Activity Presenter Interactor Retrofit Service @Module
 public class TestUserInteractorModule {
 @Provides @Singleton
 public UserInteractor provideUserInteractor() {
 return Mockito.mock(UserInteractor.class);
 }
 } //...
 @Inject UserInteractor userInteractor;
 
 @Before public void setUp() {
 TestApplicationComponent component =
 DaggerTestApplicationComponent.create();
 getAppFromInstrumentation().setComponent(component);
 component.inject(this);
 }__ //...
  • 33. Activity Presenter Interactor Retrofit Service //... @Rule public MockitoRule mockitoRule = MockitoJUnit.rule();
 
 @Mock UserInteractor userInteractor;
 
 @Before public void setUp() {
 ApplicationComponent component =
 DaggerApplicationComponent.builder()
 .userInteractorModule(new UserInteractorModule() {
 @Override
 public UserInteractor provideUserInteractor(
 StackOverflowService service) {
 return userInteractor;
 }___
 })
 .build();
 getAppFromInstrumentation().setComponent(component);
 }__ //...
  • 34. 34
  • 35. //... @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(
 ApplicationComponent.class,
 new UserInteractorModule()
 ).set(component ->
 getAppFromInstrumentation().setComponent(component));
 
 @Mock UserInteractor userInteractor; //... Activity Presenter Interactor Retrofit Service
  • 36. Activity Presenter Interactor Retrofit Service public class UserListActivityTest {
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Rule public AsyncTaskSchedulerRule asyncTaskSchedulerRule = new AsyncTaskSchedulerRule(); 
 @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(
 ApplicationComponent.class,
 new UserInteractorModule()
 ).set(component ->
 getAppFromInstrumentation().setComponent(component));
 
 @Mock UserInteractor userInteractor;
 
 @Test public void shouldDisplayUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText(
 "50 user1 - badge1nn30 user2 - badge2, badge3")));
 }
 }
  • 37. static <T> T createSubclass(final T module, final Map<Class, Object> testFields) {
 return (T) Mockito.mock(module.getClass(), new Answer() {
 @Override public Object answer(InvocationOnMock invocation) throws Throwable {
 Method method = invocation.getMethod();
 Object obj = testFields.get(method.getReturnType());
 if (obj != null) {
 return obj;
 } else {
 return method.invoke(module, invocation.getArguments());
 }
 }
 });
 } DaggerMock internals
  • 38. Activity Presenter Interactor Retrofit Service @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(
 ApplicationComponent.class,
 new UserInteractorModule()
 ).set(component ->
 getAppFromInstrumentation().setComponent(component));
  • 39. Activity Presenter Interactor Retrofit Service public class MyDaggerMockRule
 extends DaggerMockRule<ApplicationComponent> {
 
 public MyDaggerMockRule() {
 super(
 ApplicationComponent.class,
 new UserInteractorModule()
 );
 set(component ->
 getAppFromInstrumentation().setComponent(component)); 
 providesMock(UserInteractor.class, userInteractor ->
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList())
 );
 }__
 }_
  • 41. 41 public class MockPresenterTest {
 
 @Rule public ActivityTestRule<UserListActivity> rule =
 new ActivityTestRule<>(UserListActivity.class, false, false);
 
 @Rule public MyDaggerMockRule daggerMockRule =
 new MyDaggerMockRule();
 
 @Mock UserListPresenter presenter;
 
 @Test
 public void testOnCreate() {
 rule.launchActivity(null);
 
 onView(withId(R.id.text)).check(matches(withText("")));
 
 verify(presenter).reloadUserList();
 }
 } Activity Presenter Interactor Retrofit Service
  • 42. 1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code
  • 44. public class UserListPresenter {
 
 private UserInteractor userInteractor;
 
 private UserListActivity activity;
 
 public UserListPresenter(UserInteractor userInteractor, UserListActivity activity) {
 this.userInteractor = userInteractor;
 this.activity = activity;
 }
 
 public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }_
 } Activity Presenter Interactor Retrofit Service
  • 45. Activity Presenter Interactor Retrofit Service public void reloadUserList() {
 userInteractor
 .loadUsers()
 .flattenAsObservable(l -> l)
 .map(UserStats::toString)
 .reduce((s1, s2) -> s1 + "nn" + s2)
 .subscribeOn(Schedulers.io())
 .observeOn(AndroidSchedulers.mainThread())
 .subscribe(
 activity::updateText,
 activity::showError
 );
 }_

  • 46. public class UserListPresenterTest {
 
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectMocks UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 presenter.reloadUserList();
 verify(activity).updateText(anyString());
 }_
 }__ Activity Presenter Interactor Retrofit Service
  • 47. 47
  • 48. 48
  • 49. public class TrampolineSchedulerRule implements TestRule {
 
 @Override
 public Statement apply(final Statement base, Description d) {
 return new Statement() {
 @Override
 public void evaluate() throws Throwable {
 RxJavaPlugins.setIoSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 RxJavaPlugins.setComputationSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 RxJavaPlugins.setNewThreadSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 RxAndroidPlugins.setInitMainThreadSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 
 try {
 base.evaluate();
 } finally {
 RxJavaPlugins.reset();
 RxAndroidPlugins.reset();
 }
 }
 };
 }
 }
  • 50. Activity Presenter Interactor Retrofit Service public class UserListPresenterTest {
 
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 @Rule public TrampolineSchedulerRule schedulerRule =
 new TrampolineSchedulerRule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectMocks UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 presenter.reloadUserList();
 
 verify(activity).updateText(
 "50 user1 - badge1nn30 user2 - badge2, badge3");
 }__
 }_
  • 51. Activity Presenter Interactor Retrofit Service public class UserListPresenterTest {
 
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 @Rule public TrampolineSchedulerRule schedulerRule =
 new TrampolineSchedulerRule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectMocks UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 presenter.reloadUserList();
 
 verify(activity).updateText(
 "50 user1 - badge1nn30 user2 - badge2, badge3");
 }__
 }_
  • 52. Activity Presenter Interactor Retrofit Service public class UserListPresenterTest {
 
 @Rule public DaggerMockRule<ApplicationComponent> daggerMockRule =
 new DaggerMockRule<>(ApplicationComponent.class, new UserInteractorModule());
 
 @Rule public TrampolineSchedulerRule schedulerRule = 
 new TrampolineSchedulerRule();
 
 @Mock UserInteractor userInteractor;
 
 @Mock UserListActivity activity;
 
 @InjectFromComponent(UserListActivity.class) 
 UserListPresenter presenter;
 
 @Test
 public void shouldLoadUsers() {
 when(userInteractor.loadUsers()).thenReturn(
 Observable.fromArray(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ).toList());
 
 presenter.reloadUserList();
 
 verify(activity).updateText(
 "50 user1 - badge1nn30 user2 - badge2, badge3");
 }__
 }_
  • 53. 1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code trampoline scheduler
  • 55. Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }
 }
  • 56. 56
  • 57. public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_ Activity Presenter Interactor Retrofit Service
  • 58. 1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code trampoline scheduler blockingGet
  • 59. Activity Presenter Interactor Retrofit Service public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
  • 60. Activity Presenter Interactor Retrofit Service public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id()) .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
  • 61. Activity Presenter Interactor Retrofit Service public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_
  • 62. Activity Presenter Interactor Retrofit Service public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_
  • 63. Activity Presenter Interactor Retrofit Service public class UserInteractorTest {
 @Rule public MockitoRule mockitoRule =
 MockitoJUnit.rule();
 @Rule public TrampolineSchedulerRule schedulerRule =
 new TrampolineSchedulerRule();
 
 @Mock StackOverflowService stackOverflowService;
 
 @InjectMocks UserInteractor userInteractor;
 
 @Test
 public void shouldLoadUsers() {
 when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1")));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3")));
 List<UserStats> users = userInteractor.loadUsers().blockingGet();
 
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 ); }__ }_
  • 64. Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 userInteractor.loadUsers()
 .test()
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
  • 65. Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 userInteractor.loadUsers()
 .test()
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
  • 66. Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 userInteractor.loadUsers()
 .test()
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
  • 67. public class TestSchedulerRule implements TestRule {
 private final TestScheduler testScheduler = new TestScheduler();
 
 public TestScheduler getTestScheduler() {
 return testScheduler;
 }
 
 @Override
 public Statement apply(final Statement base, Description d) {
 return new Statement() {
 @Override
 public void evaluate() throws Throwable {
 RxJavaPlugins.setIoSchedulerHandler(
 scheduler -> testScheduler);
 RxJavaPlugins.setComputationSchedulerHandler(
 scheduler -> testScheduler);
 RxJavaPlugins.setNewThreadSchedulerHandler(
 scheduler -> testScheduler);
 RxAndroidPlugins.setMainThreadSchedulerHandler(
 scheduler -> Schedulers.trampoline());
 
 try {
 base.evaluate();
 } finally {
 RxJavaPlugins.reset();
 RxAndroidPlugins.reset();
 }
 }
 };
 }
 }
  • 68. Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
  • 69. when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(users ->
 assertThat(users).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 )); Activity Presenter Interactor Retrofit Service
  • 70. Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__
  • 71. Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__
  • 72. public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .flatMap(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__ Activity Presenter Interactor Retrofit Service
  • 73. Activity Presenter Interactor Retrofit Service public class UserInteractor {
 private StackOverflowService service;
 
 public UserInteractor(StackOverflowService service) {
 this.service = service;
 }___
 
 public Single<List<UserStats>> loadUsers() {
 return service.getTopUsers()
 .flattenAsObservable(l -> l)
 .take(5)
 .concatMapEager(user ->
 service.getBadges(user.id())
 .subscribeOn(Schedulers.io())
 .map(badges -> UserStats.create(user, badges))
 .toObservable()
 )____
 .toList();
 }_
 }__
  • 74. Activity Presenter Interactor Retrofit Service when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(l ->
 assertThat(l).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 ));
  • 75. when(stackOverflowService.getTopUsers()).thenReturn(
 Observable.fromArray(
 User.create(1, 50, "user1"),
 User.create(2, 30, "user2")
 ).toList());
 
 when(stackOverflowService.getBadges(1)).thenReturn(
 Single.just(Badge.createList("badge1"))
 .delay(2, TimeUnit.SECONDS));
 when(stackOverflowService.getBadges(2)).thenReturn(
 Single.just(Badge.createList("badge2", "badge3"))
 .delay(1, TimeUnit.SECONDS));
 
 TestObserver<List<UserStats>> testObserver =
 userInteractor.loadUsers().test();
 
 schedulerRule.getTestScheduler()
 .advanceTimeBy(2, TimeUnit.SECONDS);
 
 testObserver
 .assertNoErrors()
 .assertValue(check(l ->
 assertThat(l).containsExactly(
 UserStats.create(1, 50, "user1", "badge1"),
 UserStats.create(2, 30, "user2", "badge2", "badge3")
 )_
 )); Activity Presenter Interactor Retrofit Service
  • 76. 1.void method that uses RxJava schedulers 2.method that returns a synchronous RxJava object 3.method that returns an asynchronous RxJava object Testing RxJava code trampoline scheduler blockingGet TestScheduler & TestObserver
  • 77. 77 Wrapping up 1.JVM tests isolate failures and are fast and reliable 2.Using DaggerMock testing boilerplate code can be reduced 3.RxJava asynchronous code can be tested using TestObserver and TestScheduler
  • 79. Thanks for your attention! Questions?