#EvolutionaryDesign or #DesignUpfront? I believe it’s a bit of both as I always bring in my past experience and have some design in mind before I start to #tdd. I also evolve the design as I learn more about the domain and listen to what my tests are telling me.
Here’s a 2007 discussion between Jim Coplien and Uncle Bob that prompted me to write this: https://youtu.be/KtHQGs3zFAM