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JUnit with Mockito

What	Where
Fast Introduction into Assertions	vogella.com
Introduction into unit testing	tutorials.jenkov.com
Mockito documentation	docs.mockito.googlecode.com/
Comparisson: Mocks and Stubs	http://martinfowler.com/articles/mocksArentStubs.html

Fallpits

Fallpit

Descr

Async. Tests

When doing jobs on the UI thread inside a test - look out, that the test do not return, before the async UI job gets a chance to be done.

   @Test
    public void test() {

        ... UI call ...
              
        //let the UI Thread wait 1000 ms, before returning  
        long stopTimestampt = System.currentTimeMillis() + 1000;
        while (System.currentTimeMillis() < stopTimestampt) {
            Display.getDefault().readAndDispatch();
        }
    }

JUnit

Mockito

Glossar

What	Where
Mock	imitate an Object, with all methods. On default mock-methods return null, false…
Stub	getting Mock's methods return something else, than default values.
Spy	spy at object, replace some original methods.

Basics


public class MyTest {

//1. FILL THE CONTEXT

    //@Spy annotated fields are in context of Mockito and can be injected by @InjectMocks
    @Spy
    private PreferenceService service = new LocalPreferenceService();

    //@Mock annotated fields are in context of Mockito and can be injected by @InjectMocks
    @Mock(name = "service2") 
    private PreferenceService service2; 
    
    /**
    * This is important not to put multiple Objects of same type into the context by @Spy and @Mock, or there will be an ambigous situation and none of them will be injected by Mockito.
    */
    
//2. TELL THE MOCKITO TO FILL THE @Inject ANNOTATED FIELDS INSIDE OF preferenceStoreDb BY @Spy AND @Mock ANNOTATED FIELDS FROM THIS TEST
    @InjectMocks
    private RemotePreferenceStore preferenceStoreDb = new RemotePreferenceStore();

//3. INIT THE @Mock @Spy ANNOTATED OBJECTS, INJECT THEM INTO @InjectMocks ANNOTATED OBJECTS
    @Before
    public void initMocks() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void getDefaultDefaultTest() {
        ...
    }
    
}

Stub methods

The methods for mocked objects - can be forced to return some stuff.

   /* Mock the preference lookup. It's methods will be empty and must be stubed. */
    @Mock
    PreferenceLookup preferenceLookup;

    @Before
    public void initMocks() {
        MockitoAnnotations.initMocks(this);

        // stub methods, so that they return an empty list
        List<ViewablePreference<Boolean>> showNotificationPreferences = new ArrayList<>();
        
        Mockito.when(preferenceLookup.getValue(Mockito.any(ViewablePreference.class))).thenReturn(
                showNotificationPreferences);
        Mockito.when(preferenceLookup.getValue(Mockito.anyString())).thenReturn(showNotificationPreferences);

        preferenceLookup.getValue(new ViewablePreference()); // return showNotificationPreferences now
        preferenceLookup.getValue("test");                   // return showNotificationPreferences now

Test E4 Plugins

The biggest problem in testing e4 stuff - is in faking the e4 platform classes. The usual approach is to create an IEclipseContext, fill it with mocks, inject the context into classes under test.

    /* Create an Eclipse Context */
    IEclipseContext eclipseContext = EclipseContextFactory.create();

    /* Mock the preference lookup. It's methods will be empty and must be stubed. */
    @Mock
    PreferenceLookup preferenceLookup;

    /* classes under test */
    MixedMessaging mixedMessaging;
    NotificationFactory notificationFactory;

    @Before
    public void initMocks() {
        /* create all the Spy and Mock annotated objects */
        MockitoAnnotations.initMocks(this);

        /* stub methods, so that they return an empty list */
        List<ViewablePreference<Boolean>> showNotificationPreferences = new ArrayList<>();
        Mockito.when(preferenceLookup.getValue(Mockito.any(ViewablePreference.class))).thenReturn(
                showNotificationPreferences);
        Mockito.when(preferenceLookup.getValue(Mockito.anyString())).thenReturn(showNotificationPreferences);

        preferenceLookup.getValue("test"); // return showNotificationPreferences now
        
        /* add mocks to the Context */
        eclipseContext.set(PreferenceLookup.class, preferenceLookup);

        /* class under test 1 */
        eclipseContext.set(MixedMessaging.class, mixedMessaging);

        // class under test 2
        NotificationServiceCreationFunction notificationServiceCreationFunction = new NotificationServiceCreationFunction();
        notificationFactory = notificationServiceCreationFunction.compute(eclipseContext);
    }

    @Test
    public void test() {
        //test here
    }

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