Testable Android apps

Diving into problems with building Android applications and refactoring it to Clean Architecture. We will discuss different approaches for building flexible and testable Android projects. I will show how to implement MVP for your application and how to test it in efficient way.

Transcript

1. Testable Android apps
   ALIAKSANDR ZHUKOVICH
   @Alex_Zhukovich
   http://alexzh.com
   

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2. What does it mean testable?
   • Well structured source code
   • Test code base quickly
   • Test units in isolation way
   

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3. Android World
   • Context matters
   • Huge Activity, Fragment, etc.
   • Fragmentation
   • Tests require device → Slow Android tests
   • Many apps are tested in manual way
   

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4. "Standard" Android app
   • Business code in Activities, Fragments, Services, etc.
   • View and Presenter are mixed together
   • Hard to test
   

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5. Clean Code
   • Try to write clean code
   • Separate your code
   • Avoid long methods
   • Avoid huge components (Activity, Fragment, etc)
   

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6. Architectural requirements
   • Intelligibility
   • Testability
   • Independence from libraries and frameworks
   • Independence from data source
   • Independence from UI
   

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7. Clean Architecture
   https://github.com/android10/Android-CleanArchitecture
   

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8. Layers
   Presentation layer
   View
   Presenter
   Domain layer
   Business objects
   Business logic
   Interactor
   Data layer
   Repository
   API Client interfaces
   DAO interfaces
   Cloud
   DB
   Memory
   INTERACTOR INTERFACE
   REPOSITORY INTERFACE
   

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9. MVP
   

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10. Model-View-Presenter
    View Presenter Model
    

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11. View - interface
    public interface TemperatureConverterView {
    void displayResult(double value);
    void displayProgress();
    void hideProgress();
    void launchSettingsActivity();
    void displayErrorMessage(String message);
    }
    

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12. View implementation
    public class TemperatureConverterActivity extends AppCompatActivity implements TemperatureConverterView {
    @Inject TemperatureConverterPresenter mPresenter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_temperature_converter);
    ...
    }
    @Override
    public void displayResult(double value) {
    mOutputView.setText(getString(R.string.output_text_format, value));
    }
    @Override
    public void launchSettingsActivity() {
    startActivity(new Intent(this, SettingsActivity.class));
    }
    @Override
    public void displayErrorMessage(String message) {
    Snackbar.make(mResultLayout, message, Snackbar.LENGTH_LONG).show();
    }
    }
    

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13. View → Presenter
    • View tells to Presenter what need to do use Lifecycle (onStart,
    onStop) and Android View events (OnClick, onClickItem).
    @OnClick(R.id.convertButton)
    public void onConvertButtonClicked() {
    mPresenter.convertTemperature(
    mInputView.getText().toString(),
    getTemperatureUnitFromSpinner(mInputUnitSpinner),
    getTemperatureUnitFromSpinner(mOutputUnitSpinner));
    }
    

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14. Presenter
    • There can be memory leaks in Presenter
    • attachView(View view);
    • detachView();
    @Override
    protected void onStart() {
    super.onStart();
    mPresenter.attachView(this);
    }
    @Override
    protected void onStop() {
    mPresenter.detachView();
    super.onStop();
    }
    

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15. Presenter implementation
    public class TemperatureConverterPresenterImpl implements MvpPresenter {
    private TemperatureConverterView mView;
    private EventBus mEventBus;
    private ConvertTemperatureUseCase mConvertTemperatureUseCase;
    public TemperatureConverterPresenterImpl(ConvertTemperature convertTemperature, EventBus eventBus) {
    this.mConvertTemperatureUseCase = convertTemperature;
    this.mEventBus = eventBus;
    }
    @Override
    public void attachView(TemperatureConverterView mvpView) {
    /* attach view and register event bus */
    }
    public void convertTemperature() {
    ...
    mConvertTemperatureUseCase.execute(new InputData(inputValue, from, to));
    }
    @Override
    public void detachView() {
    /* detach view and unregister eventbus */
    }
    }
    

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16. UseCase
    public class ConvertTemperatureUseCaseImpl extends UseCase implements ConvertTemperatureUseCase {
    @Override
    public void run() {
    mConverterTemperatureFactory.getTemperatureConverter().convertData(mInputData, new Callback() {
    @Override
    public void onResult(final TemperatureConvertedSuccessful convertedSuccessful) {
    getMainThreadExecutor().execute(new Runnable() {
    @Override public void run() {
    mEventBus.post(convertedSuccessful);
    }
    });
    }
    });
    }
    @Override
    public void execute(InputData data) {
    this.mInputData = data;
    getInteractorExecutor().run(this);
    }
    }
    

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17. View and business logic
    NO
    

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18. Flow
    Presenter
    Use case
    Repository
    Web
    service
    Local
    

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19. Testing
    

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20. Hamcrest library
    

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21. Testing a presenter
    @RunWith(MockitoJUnitRunner.class)
    public class TemperatureConverterPresenterTest {
    @Mock TemperatureConverterView mView;
    @Mock EventBus mEventBus;
    private TemperatureConverterPresenter mPresenter;
    @Test
    public void shouldVerifyConvertDataSuccessfulWithCorrectView() {
    when(mTemperatureFactory.getTemperatureConverter()).thenReturn(mConverter);
    doNothing().when(mConverter)
    .convertData(any(InputData.class), any(ConvertTemperatureUseCase.Callback.class));
    mPresenter.attachView(mView);
    mPresenter.convertTemperature(INPUT_VALUE_STR, FROM_TEMPERATURE_UNIT, TO_TEMPERATURE_UNIT);
    mPresenter.detachView();
    verify(mEventBus).register(any());
    verify(mView).displayProgress();
    verify(mEventBus).unregister(any());
    }
    }
    

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22. Recommendation for setting up the device
    / emulator
    One small recommendation for avoiding flakiness is turning off
    animation on real or virtual devices.
    • Window animation scale
    • Transition animation scale
    • Animator duration scale
    • Settings / Developer Options/
    

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23. Hamcrest + Espresso
    public static Matcher withToolbarTitle(final Matcher textMatcher) {
    return new BoundedMatcher(Toolbar.class) {
    @Override public boolean matchesSafely(Toolbar toolbar) {
    return textMatcher.matches(toolbar.getTitle());
    }
    @Override public void describeTo(Description description) {
    description.appendText("with toolbar title: ")
    textMatcher.describeTo(description);
    }
    };
    }
    onView(withId(R.id.toolbar))
    .check(matches(withToolbarTitle( is (TITLE))));
    startsWith
    endsWith
    ...
    

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24. Testing a UI part
    @RunWith(AndroidJUnit4.class)
    public class TemperatureConverterActivityTest {
    @Rule
    public ActivityTestRule mRule =
    new ActivityTestRule<>(TemperatureConverterActivity.class);
    @Test
    public void shouldVerifyConvertingFromCelsiusToFahrenheit() {
    onView(withId(R.id.inputView))
    .perform(typeText(String.valueOf(CELSIUS_VALUE)), closeSoftKeyboard());
    setTemperatureUnit(R.id.inputTemperatureSpinner, CELSIUS_STR);
    setTemperatureUnit(R.id.outputTemperatureSpinner, FAHRENHEIT_STR);
    onView(withId(R.id.convertButton))
    .perform(click());
    onView(withId(R.id.outputView))
    .check(matches(isDisplayed()));
    onView(withId(R.id.outputView))
    .check(matches(withText(getOutputString(FAHRENHEIT_VALUE))));
    }
    }
    

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25. Testing system stuff
    • Notifications
    • App Shortcut
    • Press hardware buttons
    • Interacting with any applications
    UIAutomator
    

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26. App Shortcut
    @RunWith(AndroidJUnit4.class)
    @SdkSuppress(minSdkVersion = 25)
    public class AppShortcutTest {
    private UiDevice mDevice;
    @Before
    public void setup() {
    mDevice = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation());
    mDevice.pressHome();
    mDevice.findObject(By.desc(APPS)).click();
    mDevice.wait(Until.hasObject(By.res(PACKAGE_NEXUS_LAUNCHER,
    SEARCH_BOX_NEXUS_LAUNCHER)), TIMEOUT);
    UiObject2 search = mDevice.findObject(By.res(PACKAGE_NEXUS_LAUNCHER,
    SEARCH_BOX_NEXUS_LAUNCHER));
    search.click();
    search.setText(APP_NAME);
    }
    @Test
    public void shouldVerifyCelsiusToFahrenheitShortcut() {
    mDevice.findObject(By.desc(APP_NAME)).longClick();
    mDevice.wait(Until.hasObject(By.desc(CONVERT_CELSIUS_TO_FAHRENHEIT_DESC)),
    TIMEOUT);
    mDevice.findObject(By.desc(CONVERT_CELSIUS_TO_FAHRENHEIT_DESC)).click();
    verifyInputAndOutputUnits(CELSIUS_UNIT, FAHRENHEIT_UNIT);
    }
    }
    

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27. Notifications
    RunWith(AndroidJUnit4.class)
    @SdkSuppress(minSdkVersion = 18)
    public class CoffeeOrderDetailsActivityTest {
    @Test
    public void shouldOrderCoffeeAndVerifyNotification() {
    verifyCoffeeOrder();
    onView(withId(R.id.pay)).perform(click());
    mDevice.openNotification();
    mDevice.wait(Until.hasObject(By.text(NOTIFICATION_TITLE)), TIMEOUT);
    UiObject2 title = device.findObject(By.text(NOTIFICATION_TITLE));
    UiObject2 text = device.findObject(By.text(NOTIFICATION_TEXT));
    assertEquals(NOTIFICATION_TITLE, title.getText());
    assertEquals(NOTIFICATION_TEXT, text.getText());
    title.click();
    mDevice.wait(Until.hasObject(By.text(ESPRESSO.getName())), TIMEOUT);
    onView(withId(R.id.delivery_info))
    .check(matches(withText(mActivityRule.getActivity()
    .getString(R.string.deliver_to_username, DELIVERY_INFO))));
    verifyCoffeeOrder();
    }
    }
    

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28. Packaging
    

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29. Package by layer
    data (module)
    repository
    database
    api
    cache
    exception
    domain (module)
    model
    interactor
    executor
    abstraction
    presenter (module)
    presenter
    view
    navigation
    app
    data
    repository
    database
    api
    cache
    exception
    domain
    model
    interactor
    executor
    abstraction
    presenter
    presenter
    view
    navigation
    

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30. Package by feature
    app
    core
    data
    utils
    posts
    detail
    profile
    notification
    settings
    

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31. Continuous Integration
    

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32. Continuous Integration
    • Jenkins
    • TeamCity
    • CircleCI
    • etc
    

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33. CircleCI
    circle.yml
    

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34. Codestyle checking
    apply plugin: 'checkstyle'
    task checkstyle(type: Checkstyle) {
    description 'Checks that the code meets standards'
    group 'verification'
    configFile file('./qa-check/checkstyle.xml')
    source 'src'
    include '**/*.java'
    exclude '**/gen/**'
    classpath = files()
    ignoreFailures = false
    }
    
    
    
    
    
    
    
    
    
    
    

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35. Q & A
    • The Clean Architecture (Robert Martin/Uncle Bob)
    https://8thlight.com/blog/uncle-bob/2012/08/13/the-clean-architecture.html
    • S is for Single Responsibility Principle (Donn Felker)
    https://realm.io/news/donn-felker-solid-part-1/
    • Android Testing Codelab
    https://codelabs.developers.google.com/codelabs/android-testing/
    • Automating User Interface Tests
    https://developer.android.com/training/testing/ui-testing/index.html
    • Project
    https://github.com/AlexZhukovich/TemperatureConverterTDD
    @Alex_Zhukovich
    

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