TDD for Android

Overview of base principle Test-Driven Development. How to use TDD for Android project. Tips for creating well tested Android projects.

Project:
https://github.com/AlexZhukovich/TemperatureConverterTDD

Blog:
http://alexzh.com

Transcript

1. TDD for Android
   

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2. Why do we test?
   •Testing ensure the Quality of the product;
   •Tests help improve design code;
   •Tests check that code works;
   

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3. Observations
   • Huge activities / fragments
   • Hard to add a new feature
   • Hard to test
   • Many apps tested in manual
   way
   • Fragmentation
   • Slow Android tests
   • Required device
   • Robolectric
   • Espresso
   • etc
   

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4. Bad vs Good tests
   @Test
   public void test1() {
   mPresenter.attachView(null);
   mPresenter.convertTemperature();
   mPresenter.detachView();
   verify(mView, never()).getInputValue();
   verify(mView, never()).getFromTemperatureUnit();
   verify(mView, never()).getToTemperatureUnit();
   verify(mView, never()).setOutputValue(anyDouble());
   when(mTemperatureFactory.getTemperatureConverter())
   .thenReturn(mConverter);
   doNothing().when(mConverter).convertData(any(InputData.class));
   mPresenter.attachView(mView);
   mPresenter.convertTemperature();
   mPresenter.detachView();
   verify(mEventBus).register(any());
   verify(mView).displayProgress();
   verify(mView, times(1)).getInputValue();
   verify(mView, times(1)).getFromTemperatureUnit();
   verify(mView, times(1)).getToTemperatureUnit();
   verify(mEventBus).unregister(any());
   }
   @Test
   public void shouldVerifyConvertDataSuccessful () {
   mPresenter.attachView(mView);
   mPresenter.convertTemperature();
   mPresenter.detachView();
   verify(mEventBus).register(any());
   ...
   }
   @Test
   public void shouldVerifyConvertDataWithNullView() {
   mPresenter.attachView(null);
   mPresenter.convertTemperature();
   mPresenter.detachView();
   verify(mView, never()).getInputValue();
   ...
   }
   Don’t Do
   

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5. Bad vs Good UI tests
   @Test
   public void shouldVerifyGravity() {
   View view = ...;
   assertEquals(Gravity.START,
   view.getForegroundGravity());
   ...
   }
   @Test
   public void shouldVerifyOrderCoffee() {
   onView(withId(R.id.name_edit))
   .perform(typeText("User"),
   closeSoftKeyboard());
   onView(withId(R.id.pay))
   .perform(click());
   onView(withId(R.id.detail_text))
   .check(matches(isDisplayed()));
   }
   Don’t Do
   

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6. Value
   

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7. What is Test Driven Development (TDD)
   Green
   Refactor
   Red
   

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8. Code separations
   Android
   App
   Core
   Acceptance
   tests
   Unit
   tests
   

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9. Model-View-Presenter
   View Presenter Model
   

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10. Application overview
    Web
    service
    Local
    

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11. Application overview
    Presenter
    Use case
    Repository
    Web
    service
    Local
    

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12. 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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13. Hamcrest library
    

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14. 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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15. UI test
    @RunWith(AndroidJUnit4.class)
    public class TemperatureConverterActivityTest {
    @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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16. Presenter test
    @RunWith(MockitoJUnitRunner.class)
    public class TemperatureConverterPresenterTest {
    @Mock TemperatureConverterView mView;
    …
    private TemperatureConverterPresenter mPresenter;
    @Test
    public void shouldVerifyConvertDataSuccessfulWithCorrectView() {
    mPresenter.attachView(mView);
    mPresenter.convertTemperature();
    mPresenter.detachView();
    verify(mEventBus).register(any());
    ...
    }
    }
    

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17. Asynchronous calls using Mockito (Retrofit2)
    @RunWith(MockitoJUnitRunner.class)
    public class OnlineConverterTemperatureTest {
    private OnlineConverterTemperature mConverter;
    @Mock EventBus mEventBus;
    @Mock TemperatureConverterApiService mApiService;
    @Mock Call mCall;
    @Mock ResponseBody mResponseBody;
    @Captor ArgumentCaptor> argumentCapture;
    @Test
    public void shouldGetConvertedResult() {
    when(mApiService.getConvertedData(anyString(), anyString(), anyString()))
    .thenReturn(mCall);
    Response response = Response.success(mConvertedResult);
    mConverter.convertData(mInputData);
    verify(mCall).enqueue(argumentCapture.capture());
    argumentCapture.getValue().onResponse(null, response);
    verify(mEventBus).post(new TemperatureConvertedSuccessful(mConvertedResult));
    }
    }
    

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18. Testing system stuff
    • Notifications;
    • Press hardware buttons;
    • Interacting with any applications.
    UI Automator
    

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19. Continuous Integration (CIRCLE CI)
    circle.yml
    

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20. Testing tips
    

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21. Focus on App
    behaviour
    

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22. Use available
    stuff
    

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23. Use hamcrest
    library
    

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24. Do not copy
    your code
    between tests
    

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25. Launch directly
    desire screen
    

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26. Many small
    tests are
    better that big
    ones
    

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27. Test your
    code, not using
    libraries
    

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28. Test-Driven
    Development is
    NOT a silver
    bullet
    

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29. Thank you
    1. Getting Started with Testing (Android)
    https://developer.android.com/training/testing/start/index.html
    2. Espresso
    https://google.github.io/android-testing-support-library/docs/espresso/
    3. Ui Automator
    https://developer.android.com/training/testing/ui-testing/uiautomator-testing.html
    4. Robolectric
    http://robolectric.org/
    5. Project
    https://github.com/AlexZhukovich/TemperatureConverterTDD
    6. Blog
    http://alexzh.com/
    @Alex_Zhukovich
    

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