We're in violent agreement that startups should write as little code as humanly possible. I learned that lesson the hard way. You should test your ideas first.

We're in violent agreement that startups should write as little code as humanly possible. I learned that lesson the hard way. You should test your ideas first. But sooner or later, you'll get a rough idea of what people need, and you'll throw together a working prototype. After all, users don't visualize well, but they're great at extrapolating from things they can see. That's when I start writing tests, even if it's just a weekend prototype. Because for me, tests are a net win by the afternoon of day 1. Why should I spent 3 days writing nasty crap when I could have a decent program in 2? Now, this won't work for everybody. Maybe it takes a month to prototype your idea. Maybe it takes you twice as long to do TDD as it does to churn out code. Maybe your idea is just plain hard to test. But I'm definitely in complete agreement about customer validation.