Differential Coverage for Debugging. Take a failing test. You have no idea where the underlying issue might be. The system you’re working with is possibly deep, wide, and eldritch.
Your move:
- run the tests and capture code coverage without the failing test
- run the tests and capture code coverage with the failing test
- diff the line-by-line code coverage(s) to see which lines are executed in the failing case only
- eliminate further red herrings by mental elimination
Very clever! Via Thorsten Ball.