Depending on your problem domain, it may be easier or harder to create interfaces between all these TDD'd, isolated modules. Aren't you assuming that TDD requi

Depending on your problem domain, it may be easier or harder to create interfaces between all these TDD'd, isolated modules. Aren't you assuming that TDD requires pervasive unit isolation? I practice TDD often and prefer not to isolate units at least at the level of filesystem artifact. I believe that one of the reasons test-first became TDD and gave up on the distinction between unit tests and acceptance tests is because the Smalltalk sUnit style of testing units as units didn't work so well in languages which aren't Smalltalk.