I always love to compare Peter Norvig’s sudoku solver implementation [1] versus Ron Jeffries TDD approach [2]. Norvig starts with the theory building and creat

I always love to compare Peter Norvig’s sudoku solver implementation [1] versus Ron Jeffries TDD approach [2]. Norvig starts with the theory building and creates a constraint solver in about 50 lines of code. Jeffries starts with TDD, assumes an implementation, has to change that implementation, therefore has to change the tests, and after a series of five blog posts kind of fizzles out on it. To me it just highlights that defining the problem is with so much more than defining the tests, as you can’t write a test for a problem you haven’t defined yet. In this way the tests are an imposition. In short to me it shows that TDD only really works if you already knew how to buold the project to begin with. [1] https://norvig.com/sudoku.html https://norvig.com/sudoku.html [2] https://ronjeffries.com/xprog/articles/oksudoku/ https://ronjeffries.com/xprog/articles/oksudoku/