[FIXED] Method with Interface Parameters with Mockito Argument Capture

Issue

I've one simple question. I've got two classes

XMessage and YMessage. These two classes are the sub class of ZClass.

These messages are published from a PublisherService with method

public void publish(ZClass message, Properties props){
     // some lowlevel stuff.
     // note that method is taking ZClass as an arg.
}

According to my logic XMessage is sent many times while YMessage is sent only once in one test.

Let's say XMessage is supposed to be sent 4 times where YMessage is sent 1 time. I would assume below code would work.

        ArgumentCaptor<XMessage> xCaptor = ArgumentCaptor.forClass(XMessage.class);

        verify(publisherService, times(4)).sendMessage(isA(XMessage.class),any());
        verify(publisherService, times(1)).sendMessage(isA(YMessage.class),any());
        verify(publisherService, times(4)).sendMessage(xCaptor,any());

However it fails with captor and the captor has 5 values.

What am I doing wrong?

Thanks in advance.

Solution

This is a known issue in Mockito. The issue is that ArgumentCaptor is not type aware.

See https://github.com/mockito/mockito/issues/565

This is open from 2016 and still not fully fixed so I would just did some workaround around it.

You can capture all of the arguments and then instanceof just the ones you need.

ArgumentCaptor<ZClass> zCaptor = ArgumentCaptor.forClass(ZClass.class);

Mockito.verify(publisherService, times(5)).publish(zCaptor.capture(), ArgumentMatchers.<Properties>any());

List<XMessage> xMessages = zCaptor.getAllValues()
                                  .stream()
                                  .filter(arg -> arg instanceof XMessage)
                                  .map(arg -> (XMessage) arg)
                                  .collect(Collectors.toList());

Answered By - Pavel Polivka
Answer Checked By - Pedro (JavaFixing Volunteer)