The document discusses the Model-View-Presenter (MVP) pattern for developing Android applications. It describes the roles of the model, view, and presenter, and how the presenter acts as a mediator between the model and view. It also covers how to implement MVP for a sample "TaskIt" app, including defining view and presenter interfaces. Finally, it discusses how to test MVP apps through dependency injection and mocking the model and view in unit and UI tests.

1. Model View Presenter
Michael Cameron@Darxval

2. Getting Started - Name that
Pattern!

3. Model - View -
Controller

4. Pros and Cons?
• What are some pros and cons of MVC?

5. Name that Pattern!

6. Model - View -
Presenter

7. Views
• Not to be confused with widget.view
• The view is a tattle tale
• Rule your views with an Iron Fist
• Tell it what to do
• Let the view tell you of everything that happens.

8. View Interfaces
• Don’t Trust any class, always have a contract
• Contract Details:
• View must let the presenter tell it what to do.
• View must let the presenter know of any events it
has received

9. Presenter
• Tells the view and model objects what to do.
• Handles events

10. TaskIt!
• Add Tasks
• Have a list of Tasks
• Look at a task in detail

11. TaskIt MVP

12. TasksContract
interface View {
void setProgressIndicator(boolean active);
void showTasks(List<Task> tasks);
void showAddTask();
void showTaskDetailUi(String taskId);
}
interface UserActionsListener {
void loadTasks(boolean forceUpdate);
void addNewTask();
void openTaskDetails(@NonNull Task requestedTask);
}

13. So… How do you test
this??

14. Inversion of Control
• All you have to do is inject a mock instead of a
concrete object to test parts of the app.

15. Inversion of Control
public AddTaskPresenter(@NonNull TasksRepository tasksRepository,
@NonNull AddTaskContract.View addTaskView,
@NonNull ImageFile imageFile) {
mTasksRepository = checkNotNull(tasksRepository);
mAddTaskView = checkNotNull(addTaskView);
addTaskView.setUserActionListener(this);
mImageFile = imageFile;
}

16. Mock vs Concrete
/** Prod Debug**/
public class Injection {
public static ImageFile provideImageFile() {
return new ImageFileImpl();
}
public static TasksRepository provideTasksRepository() {
return TaskRepositories.getInMemoryRepoInstance(new TasksServiceApiImpl());
}
}
/** Mock Debug**/
public class Injection {
public static ImageFile provideImageFile() {
return new FakeImageFileImpl();
}
public static TasksRepository provideTasksRepository() {
return TaskRepositories.getInMemoryRepoInstance(new FakeTasksServiceApiImpl());
}
}

17. Unit Testing
public class TaskDetailPresenterTest {
public static final String INVALID_ID = "INVALID_ID";
public static final String TITLE_TEST = "title";
public static final String DESCRIPTION_TEST = "description";
@Mock
private TasksRepository mTasksRepository;
@Mock
private TaskDetailContract.View mTaskDetailView;
/**
* {@link ArgumentCaptor} is a powerful Mockito API to capture argument values and use them to
* perform further actions or assertions on them.
*/
@Captor
private ArgumentCaptor<TasksRepository.GetTaskCallback> mGetTaskCallbackCaptor;
private TaskDetailPresenter mTaskDetailsPresenter;
@Before
public void setupNotesPresenter() {
// Mockito has a very convenient way to inject mocks by using the @Mock annotation. To
// inject the mocks in the test the initMocks method needs to be called.
MockitoAnnotations.initMocks(this);
// Get a reference to the class under test
mTasksDetailsPresenter = new TaskDetailPresenter(mTaskRepository, mTaskDetailView);
}

18. Espresso Test
@RunWith(AndroidJUnit4.class)
@LargeTest
public class TaskDetailScreenTest {
private static String TASK_TITLE = "TaskIt";
private static String TASK_DESCRIPTION = "Rocks";
private static String TASK_IMAGE = "file:///android_asset/atsl-logo.png";
/**
* {@link Note} stub that is added to the fake service API layer.
*/
private static Task TASK = new Task(TASK_TITLE, TASK_DESCRIPTION, TASK_IMAGE);
@Rule
public ActivityTestRule<TaskDetailActivity> mTaskDetailActivityTestRule =
new ActivityTestRule<>(TaskDetailActivity.class, true /* Initial touch mode */,
false /* Lazily launch activity */);
@Test
public void noteDetails_DisplayedInUi() throws Exception {
// Check that the note title, description and image are displayed
onView(withId(R.id.task_detail_title)).check(matches(withText(TASK_TITLE)));
onView(withId(R.id.task_detail_description)).check(matches(withText(TASK_DESCRIPTION)));
onView(withId(R.id.task_detail_image)).check(matches(allOf(
hasDrawable(),
isDisplayed())));
}
}

19. Sources:
MVP
https://github.com/konmik/nucleus
Google
http://code-labs.io/codelabs/android-testing
J. Amourette -
plus.google.com/u/0/photos/102898026333733818285/albums/6081914916274644193/6081914917317951522?pid=6081914917317951522&oid=1028980263337338
Thank You!