Random Mockito Stubbing exception

[Jonathan Cook]

Hello,

I have the following unit test using Mockito which has happily been passing for months/years.

        @Test
        public void testAddRemoveTarFile() throws IOException, GeneralSecurityException {
        //add a TAR file
        TableRowCount downloadRowCount = new TableRowCount(tableDownloads);
       
        //create the item that will appear in the table row
        MyHSAItem item = createMyHSAItem();
        Mockito.when(model.getConfigurations(Type.TAR)).thenReturn(Arrays.asList(item));
       
        //get the table model
        JTable downloadsTable = (JTable)UI.findComponent(getPanel(), "download");
        final MyHSATableModel tableModel = (MyHSATableModel ) downloadsTable.getModel();
       
        final MyHSAEvent event = Mockito.mock(MyHSAEvent.class);
        Mockito.when(event.getType()).thenReturn(MyHSAEvent.Type.MODEL);
       
        //Fire table event when adding observation
        final File xmlFile = Mockito.mock(File.class);
        Mockito.doAnswer(new Answer<Void>() {
            @Override
            public Void answer(InvocationOnMock invocation) throws Throwable {
                tableModel.modelChanged(event);
                return null;
            }
        }).when(model).addObservation(xmlFile);
       
        //Fire table event when deleting observation
        Mockito.doAnswer(new Answer<Void>() {
            @Override
            public Void answer(InvocationOnMock invocation) throws Throwable {
                tableModel.modelChanged(event);
                return null;
            }
        }).when(model).delete(item, true);

        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                UI.findButtonWithText(getPanel(), "Add ...").doClick();
            }
        });

        //select a file, table row should update
        chooseFile(xmlFile);
        ensureEquals(1, downloadRowCount, TIMEOUT);
       
        // Remove download + cancel
        UI.leftClick(tableDownloads);
        clickRemove("Cancel");
        ensureEquals(1, downloadRowCount, TIMEOUT);

        // Remove download + OK
        UI.leftClick(tableDownloads);
        Mockito.when(model.getConfigurations(Type.TAR)).thenReturn(new ArrayList<MyHSAItem>());
        clickRemove("OK");
        ensureEquals(0, downloadRowCount, TIMEOUT);
    }

Suddenly it failed just once with:

    org.mockito.exceptions.misusing.UnfinishedStubbingException:
    Unfinished stubbing detected here:
    -> at herschel.ia.pal.pool.hsa.gui.MyHsaPreferencePanelTest.testAddRemoveTarFile(MyHsaPreferencePanelTest.java:257)

    E.g. thenReturn() may be missing.
    Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);
    when(mock.isOk()).thenThrow(exception);
    doThrow(exception).when(mock).someVoidMethod();
    Hints:
    1. missing thenReturn()
   
 2. although stubbed methods may return mocks, you cannot inline mock
creation (mock()) call inside a thenReturn method (see issue 53)

I understand this error but not how it can randomly happen. The Mockito.doAnswer seems to be the problem. I am not inlining mocks and it seems to be ok and has always worked. What can it be?

Line 257 stars with

Mockito.doAnswer(new Answer<Void>() {

model is a field initialised like so, I thought it could be something to do with the setup/teardown of model?

    @Mock
    private MyHSANotifiableModelImpl model;

    public void setUpPanel() {
        MockitoAnnotations.initMocks(this);

Thanks for any help

[jianhua zhou]

Hi Jonathan,

I get the exactly same problem as you did.

My test was stable for months and then suddenly failed with that mockito exception.

Did you get a solution at the end?

Thanks,

Jianhua