Ok my turn... I'd do TDD even on my own (for non-spike/experimental/prototype code) because
- Think before you leap: forces me to think what I want to get done before i start cranking out code. What am I trying to accomplish here.. 'If I assume I already had this piece.. how would I expect it to work?' Encourages interface-in design of objects.
- Easier to change: I can make modifications with confidence.. 'I didn't break anything in step1-10 when i changed step5.' Regression testing is instantaneous
- Better designs emerge: I've found better designs emerging without me investing effort in a design activity. test-first + Refactoring lead to loosely coupled, minimal classes with minimal methods.. no overengineering.. no YAGNI code. The classes have better public interfaces, small methods and are more readable. This is kind of a zen thing.. you only notice you got it when you 'get it'.
- The debugger is not my crutch anymore : I know what my program does.. without having to spend hours stepping thru my own code. Nowadays If I spend more than 10 mins with the debugger.. mental alarms start ringing.
- Helps me go home on time I have noticed a marked decrease in the number of bugs in my code since TDD.. even if the assert is like a Console trace and not a xUnit type AT.
- Productivity / Flow: it helps me to identify the next discrete baby-step that will take me towards done... keeps the snowball rolling. TDD helps me get into a rhythm (or what XPers call flow) quicker. I get a bigger chunk of quality work done per unit time than before. The red-green-refactor cycle turns into... a kind of perpetual motion machine.
- I can prove that my code works at the touch of a button
- Practice makes perfect I find myself learning & spotting dragons faster.. with more TDD time under my belt. Maybe dissonance.. but I feel that TDD has made me a better programmer even when I don't go test first. Spotting refactoring opportunities has become second nature...
I'll update if I think of any more.. this is what i came up with in the last 2 mins of reflection.
