Comment by weef

Great advice. Writing integration tests or unit tests around existing functionality is extremely important but unfortunately might not always be feasible given the time, budget, or complexity of the code base. I just completed a new feature for an existing and complex code base but was given the time to write an extensive set of end-to-end integration tests covering most scenarios before starting my coding. This proved invaluable once I started adding my features to give me confidence I wasn't breaking anything and helped find a few existing bugs no one had caught before!