While writing something else entirely, I stumbled upon one of my earliest contributions to the evolutionary design/TDD community. I called them abstract test cases at the time, but today we know them as contract tests. Has much changed in the 20 years since I first wrote about this in public? No. I use contract tests to gain confidence that a module implements its declared protocol. If you prefer OOP terms, i use contract tests to gain confidence that a class implements its declared interface...
