How to do argument capture with spock framework?

Question

I have some Java stuff like this:

public interface EventBus{
    void fireEvent(GwtEvent<?> event);
}


public class SaveCommentEvent extends GwtEvent<?>{
    private finalComment oldComment;
    private final Comment newComment;

    public SaveCommentEvent(Comment oldComment,Comment newComment){
        this.oldComment=oldComment;
        this.newComment=newComment;
    }

    public Comment getOldComment(){...}
    public Comment getNewComment(){...}
}

and test code like this:

  def "...."(){
     EventBus eventBus=Mock()
     Comment oldComment=Mock()
     Comment newCommnet=Mock()

     when:
         eventBus.fireEvent(new SaveCommentEvent(oldComment,newComment))

     then:
         1*eventBus.fireEvent(
                                {
                                   it.source.getClass()==SaveCommentEvent;
                                   it.oldComment==oldComment;
                                   it.newComment==newComment
                                 }
                              )            
}

I want to verify that the eventBus.fireEvent(..) gets called once with an Event with type SaveCommentEvent and construction parameters oldComment and newComment.

Code runs without errors but problem is:

After changing closure stuff from

{
   it.source.getClass()==SaveCommentEvent;
   it.oldComment==oldComment;  //old==old
   it.newComment==newComment   //new==new
}

To

 {
    it.source.getClass()==Other_Class_Literal;
    it.oldComment==newComment;  //old==new
    it.newComment==oldComment   //new==old
  }

Still, code runs without error? Apparently the closure didn't do what I want, so the question is: How to do argument capturing?

Answer 1

I got it:

    SaveCommentEvent firedEvent

    given:
     ...

    when:
     ....

    then:
    1 * eventBus.fireEvent(_) >> {arguments -> firedEvent=arguments[0]}
    firedEvent instanceof SaveModelEvent
    firedEvent.newModel == newModel
    firedEvent.oldModel == oldModel

Answer 2

then:
     1*eventBus.fireEvent(
                            {
                               it.source.getClass()==SaveCommentEvent;
                               it.oldComment==oldComment;
                               it.newComment==newComment
                             }
                          )            

In your code it is a Groovy Closure Implicit Variable reference to a mock eventBus Interface which has no fields. How could you verify them?

Also, I think the order of events that has to happen to use Spock Mocks is not necessarily intuitive. I would write it up here except it would not be as good as Kenneth Kousen's explanation.