Lots! How to test-drive (as opposed to test-after), how to mock out integration points, what mocks/testdoubles/spies are and how they differ. I also learned tha

Lots! How to test-drive (as opposed to test-after), how to mock out integration points, what mocks/testdoubles/spies are and how they differ. I also learned that Enterprise Java is a particular level of hell. In all, it was a good experience though :)