JMock, What should you do when the mock object gets casted to a concrete class?

Question

Not sure how I should be asking the question, but when I define my mock objects, and somewhere in the code it attempts to cast it to a different type the test throws me

$Proxy6 cannot be cast to ...

How does one solve this problem?

Answer 1

Does this class really need to be mocked? I usually mock services and use concrete classes for value types passed in.

One thing you can do is outlined here: define an interface in your test.

If it really needs to be mocked and you can't do the above you could provide your own implementation which does what you want the mock to do e.g. records values passed in, methods called, returns the values you want etc. and assert what you need at the end - that might be a lot of work though.

Lastly, is this pointing you towards some unidentified interfaces in your design or that the code under test needs some refactoring?

Answer 2

As always, the test is telling you something about your design. Why is the code trying to cast the object? Could you give us more detail?