When I teach evolutionary design, participants still often ask me which tools they ought to use to introduce test doubles into their projects. Yes, I nudge them gently in the direction of focusing on principles and techniques and away from fixating on tools, but they still need a place to start. This question often comes in the following form: Do you favor hand-rolling test doubles or using a library (like NSubstitute, Mockito, or rspec-mock)? I choose the option that balances removing duplic...
