[mitjak]

right, i'm talking about implementing something new. if you're trying to refactor or alter an existing codebase, it can be even easier: you add another test to an already existing suite.

i don't think i've ever sat down, written tests for a completely new implementation, only to find that i need to add a field somewhere. before i sit down to write tests, i do some preliminary thinking. i'm not saying, write tests without ever trying to think first. but do use tests to flesh out your change from outside of the black box.