Cannot debug Mockito / JUnit code in Eclipse, works fine with just JUnit

Question

I've got JUnit tests that run just fine. Added Mockito to my build and I try to put a breakpoint in my JUnit test that uses Mockito to mock out some of the public methods. When I try to run the debugger on the class, I get the error "unable to install breakpoint in XXX due to missing line number attributes. Modify compiler options to generate line number attributes." I checked my compiler and I generate line numbers is selected.

Answer 1

The exception you're seeing is caused by attempting to debug dynamically generated empty mock methods created by the mock() function. From your question, it looks like you actually want to be using partial mocks instead of full mocks, where only some methods are mocked and the remaining calls are delegated to the real implementation.

To create partial mocks, you should be using the spy() method instead of the mock() method. So, use

MyClass myMock = spy(new MyClass());

instead of

 MyClass myMock = mock(MyClass.class);