And if it ends up being un-important, what then? My contention here is that if you can't pursue small ideas that might end up being unimportant, you're limiting yourself creatively in a big way.
These methods exemplify the sort of complexity I was getting at in the blog post; how many tests do you end up writing if you need a full debug server?
Midje and Cascalog make it possible to do test-driven development at large scale. Is anyone else in MapReduce able to practice TDD? Really curious here.