To me this is confusing the level of abstraction tests sit with when the tests are written. You can write system tests first and you can write unit tests last, they are orthogonal.
I practice double-loop TDD, which involves writing a system level test to drive out some behaviour, then writing other integration or unit tests down through the layers until the system test passes.
I practice double-loop TDD, which involves writing a system level test to drive out some behaviour, then writing other integration or unit tests down through the layers until the system test passes.