MVP with Dagger2 and unit testing

1. Building maintainable
app with MVP and
Dagger2
KRISTIJAN JURKOVIĆ
ANDROID TEAM LEAD @ INFINUM

2. We're hiring.
HTTPS://INFINUM.CO/CAREERS

3. We're an independent
design & development
agency.

5. INFINUM
• 90+ people in 3 offices
• 15 android developers
• hundreds of projects

6. OUR BIGGEST ISSUES?

7. “Sometimes when you fill a vacuum, it still
sucks.”
― Dennis Ritchie

8. MVP TO THE RESCUE?

9. PROGRAM TO INTERFACES
NOT IMPLEMENTATIONS

10. ModelPresenterView

11. LoginActivity LoginPresenterImpl LoginInteractorImpl
LoginView LoginPresenter LoginInteractor
showLoading()
hideLoading()
setUsernameError()
setPasswordError()
showLoading()
hideLoading()
setUsernameError()
setPasswordError()
login(username, pass)
loginPresenter loginView
loginInteractor
login(username, pass) login(username, pass,
listener)
login(username, pass,
listener)
VIEW PRESENTER MODEL

12. public interface HomeView {
...
}
public interface HomePresenter {
...
}
public interface CurrencyInteractor {
...
}
VIEW
PRESENTER
MODEL

13. public interface HomeView {
...
}
VIEW

14. public class HomeActivity
extends BaseActivity
implements HomeView {
// this is an interface
HomePresenter presenter;
...
}

15. public interface HomePresenter {
...
}
PRESENTER

16. public class HomePresenterImpl
implements HomePresenter {
// interface
private HomeView view;
// and another interface
private CurrencyInteractor interactor;
public HomePresenterImpl(
HomeView view, CurrencyInteractor interactor) {
this.view = view;
this.interactor = interactor;
}
...
}

17. public interface CurrencyInteractor {
...
}
MODEL

18. public class CurrencyInteractorImpl
implements CurrencyInteractor {
...
}

19. HOW SHOULD I GET MY
CONTENT?

20. public interface HomeView {
void showCurrencies(List<Currency> currencies);
}
public interface HomePresenter {
void loadCurrencyList();
}
public interface CurrencyInteractor {
void getCurrencyList(CurrencyListener listener);
}

21. public class HomeActivity
extends BaseActivity
implements HomeView {
private void init() {
presenter = new HomePresenterImpl(this,
new CurrencyInteractorImpl());
presenter.getCurrencyList();
}
@Override
public void showCurrencies(List<Currency> currencies) {
// display data
}
}

22. public class HomePresenterImpl
implements HomePresenter {
...
@Override
public void loadCurrencyList() {
interactor.getCurrencyList(...);
}
}

23. public class CurrencyInteractorImpl
implements CurrencyInteractor {
...
@Override
public void getCurrencyList(
CurrencyListener listener) {
// do API/DB call
// return result with listener
}
}

24. VIEW SHOULDN’T CREATE ITS
DEPENDENCIES

25. DEPENDENCY INJECTION

26. JSR 330
• 5 annotations - @Named, @Inject, @Qualifier, @Scope,
@Singleton
• 1 interface - Provider<T>

27. DAGGER2 TO THE RESCUE

28. DAGGER 2
• @Module, @Provides, @Component, @Subcomponent,
ScopedProvider
• Injection into Fields, Constructors, Methods
• Each @Inject has to have its @Provides

29. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE

30. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE

31. @Module
public class ApiModule {
@Provides
@Singleton
public ApiService provideApiService(
OkHttpClient client, BaseUrl endpoint,
Converter.Factory converter) {
return RestUtils.createApiService(
client, endpoint, converter,
ApiService.class);
}
}

32. @Module
public class ApiModule {
@Provides
@Singleton
public ApiService provideApiService(
OkHttpClient client, BaseUrl endpoint,
Converter.Factory converter) {
return RestUtils.createApiService(
client, endpoint, converter,
ApiService.class);
}
}

33. @Module
public class ApiModule {
@Provides
@Singleton
public ApiService provideApiService(
OkHttpClient client, BaseUrl endpoint,
Converter.Factory converter) {
return RestUtils.createApiService(
client, endpoint, converter,
ApiService.class);
}
}

34. @Module
public class GsonConverterModule {
@Provides
@Singleton
public Converter.Factory
provideConverter(Gson gson) {
return GsonConverterFactory.create(gson);
}
}

35. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE
EXECUTORS
MODULE

36. @Component(modules = {
HostModule.class,
GsonConverterModule.class,
ClientModule.class,
LoggerModule.class,
ExecutorsModule.class,
ApiModule.class,
GsonModule.class
})
@Singleton
public interface AppComponent {
}

37. public class MyApplication extends Application {
protected AppComponent appComponent;
protected void init() {
appComponent = DaggerAppComponent.create();
}
}

38. HOW CAN WE REUSE THAT
IN OUR ACTIVITIES?

39. public class HomeActivity
extends BaseActivity
implements HomeView {
private void init() {
presenter = new HomePresenterImpl(this,
new CurrencyInteractorImpl());
presenter.getCurrencyList();
}
@Override
public void showCurrencies(List<Currency> currencies) {
// display data
}
}

40. • Inject presenter into view
• Inject view and interactor into presenter

41. @Module
public class HomeModule {
private HomeView view;
public HomeModule(HomeView view) {
this.view = view;
}
@Provides
public HomeView provideView() {
return view;
}
@Provides
public HomePresenter providePresenter(HomePresenterImpl presenter) {
return presenter;
}
@Provides
public CurrencyInteractor provideInteractor(
CurrencyInteractorImpl interactor) {
return interactor;
}
}

42. @Module
public class HomeModule {
private HomeView view;
public HomeModule(HomeView view) {
this.view = view;
}
@Provides
public HomeView provideView() {
return view;
}
@Provides
public HomePresenter providePresenter(HomePresenterImpl presenter) {
return presenter;
}
@Provides
public CurrencyInteractor provideInteractor(
CurrencyInteractorImpl interactor) {
return interactor;
}
}

43. @Module
public class HomeModule {
private HomeView view;
public HomeModule(HomeView view) {
this.view = view;
}
@Provides
public HomeView provideView() {
return view;
}
@Provides
public HomePresenter providePresenter(HomePresenterImpl presenter) {
return presenter;
}
@Provides
public CurrencyInteractor provideInteractor(
CurrencyInteractorImpl interactor) {
return interactor;
}
}

44. public class CurrencyInteractorImpl
implements CurrencyInteractor {
@Inject
public CurrencyInteractorImpl(ApiService service) {
}
}

45. public class CurrencyInteractorImpl
implements CurrencyInteractor {
@Inject
public CurrencyInteractorImpl(ApiService service) {
}
}

46. @Module
public class HomeModule {
private HomeView view;
public HomeModule(HomeView view) {
this.view = view;
}
@Provides
public HomeView provideView() {
return view;
}
@Provides
public HomePresenter providePresenter(HomePresenterImpl presenter) {
return presenter;
}
@Provides
public CurrencyInteractor provideInteractor(
CurrencyInteractorImpl interactor) {
return interactor;
}
}

47. public class HomePresenterImpl
implements HomePresenter {
@Inject
public HomePresenterImpl(HomeView view,
CurrencyInteractor interactor) {
this.view = view;
this.interactor = interactor;
}
}

48. public class HomeActivity
extends BaseActivity
implements HomeView {
@Inject
HomePresenter presenter;
}

49. @Subcomponent(modules = HomeModule.class)
public interface HomeComponent {
void inject(HomeActivity activity);
}

50. WHAT’S THAT
“SUBCOMPONENT” THING
YOU MENTIONED?

51. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE
HOME
MODULE
HOMECOMPONENT
EXECUTORS
MODULE

52. @Component(modules = {
...
})
@Singleton
public interface AppComponent {
HomeComponent plus(HomeModule module);
}

53. public abstract class BaseActivity
extends AppCompatActivity {
Override
protected void onCreate(Bundle savedInstanceState) {
...
injectDependencies(MyApplication.getAppComponent());
}
protected abstract
void injectDependencies(AppComponent appComponent);
}

54. public class HomeActivity
extends BaseActivity
implements HomeView {
protected void
injectDependencies(AppComponent appComponent) {
appComponent
.plus(new HomeModule(this))
.inject(this);
}
}

55. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE
HOME
MODULE
HOMECOMPONENT
SESSIONCOMPONENT
SESSION
MODULE
EXECUTORS
MODULE

56. SATISFACTION LEVEL 9001

57. “If you don’t like testing your product, most
likely your customers won’t like to test it
either.”

58. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE
EXECUTORS
MODULE

59. APP COMPONENT
HOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE
EXECUTORS
MODULE

60. APPTESTCOMPONENT
MOCKHOST
MODULE
CONVERTER
MODULE
CLIENT
MODULE
LOGGER
MODULE
API
MODULE
GSON
MODULE
SYNC
EXECUTORS
MODULE

61. @Component(modules = {
...
MockHostModule.class,
SynchronousExecutorsModule.class,
...
})
@Singleton
public interface AppTestComponent extends AppComponent {
void inject(MyTestApplication app);
}

62. @Component(modules = {
...
MockHostModule.class,
SynchronousExecutorsModule.class,
...
})
@Singleton
public interface AppTestComponent extends AppComponent {
void inject(MyTestApplication app);
}

63. @Component(modules = {
...
MockHostModule.class,
SynchronousExecutorsModule.class,
...
})
@Singleton
public interface AppTestComponent extends AppComponent {
void inject(MyTestApplication app);
}

64. public class MyTestApplication
extends MyApplication
implements TestLifecycleApplication {
@Override
protected void init() {
appComponent = DaggerAppTestComponent.create();
}
}

65. protected void enqueueResponse(String filename) {
String body = ResourceUtils.readFromFile(filename);
MockResponse mockResponse =
new MockResponse()
.setBody(body)
.setResponseCode(HttpURLConnection.HTTP_OK);
mockWebServer.enqueue(mockResponse);
}

66. @Override
public void setup() throws Exception {
super.setup();
controller = Robolectric
.buildActivity(MockActivity.class)
.create()
.start()
.resume()
.visible();
fragment = DashboardDrivingModeFragment.newInstance();
controller.get().getSupportFragmentManager()
.beginTransaction()
.replace(R.id.container, fragment, null)
.commit();
ButterKnife.bind(this, fragment.getView());
}

67. @Test
public void testEmptyStateNotVisible() {
enqueueResponse(“rest-currency-response.json”);
btnCurrencyList.performClick();
assertThat(emptyView).isNotVisible();
}

68. THINGS TO REMEMBER
• Orientation change

69. THINGS TO REMEMBER
• Dagger2 is a powerful tool - make good use of it
• Save yourselves from regression bugs

70. REFERENCES
• http://antonioleiva.com/mvp-android/
• https://medium.com/@czyrux/presenter-surviving-
orientation-changes-with-
loaders-6da6d86ffbbf#.xou7c71uz
• http://frogermcs.github.io/dependency-injection-with-
dagger-2-custom-scopes/
• https://www.youtube.com/watch?v=oK_XtfXPkqw

71. We're hiring.
HTTPS://INFINUM.CO/CAREERS

72. Any questions?
KRISTIJAN.JURKOVIC@INFINUM.CO
@KJURKOVIC
Visit infinum.co or find us on social networks:
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