TDD has always meant to write your tests first. Red, green, refactor. If you're not doing TFD, you're not doing TDD; you're just developing with tests. TDD is test-driven precisely because all implementation code is written to make some failing test pass. Code not so written is by definition broken and does not make it into production. (If you need to try out an idea without writing tests first, that's called a spike and it should be thrown away after proving what you set out to prove with it.)
