Comment by gruseom
15 years ago
I agree that there is a serious criticism here, and that sufficiently deep thinking is underrated.
TDD advocates tend to assume that you can always iterate your way to a solution. But what you get by iteration is sensitive to how you start. Technically, yes, you can evolve any program A into any other program B, but in practice no: the class of programs that A will evolve into is sharply constrained by A. I think this is true no matter how small A is. If that's correct, then initial conditions are a lot more important than it's fashionable to think they are.
Still, this isn't a weakness of TDD per se, but of iterative approaches in general, and it's something that advocates for iterative development of software (and other things) haven't yet taken into account. That's understandable, because the advent of iterative approaches was so necessary and has proven so valuable in other ways. These things come in historical waves.
A point about the Sudoku "debacle", though. The posts by Ron Jeffries are indicative of something other than TDD. They're indicative of mucking around in public. The difference isn't that other people don't make embarrassing mistakes; it's that they hide them. Why would Jeffries exhibit his so blatantly? If he were just a bad programmer or a zealot or a dishonest guru, obviously he'd have suppressed them. Not one of those types is ever too dumb to do that. (Typically, they're quite good at it. Maybe that's where their intelligence goes!) So something else is going on, and I found it unfair that no one who wrote about the Sudoku "debacle" ever asked what it might be.
My guess is that it's the original XP culture. These guys practice a let-it-all-hang-out style in which they highlight their mistakes and affect being stupider than they really are. Kent Beck affects this "I'm an idiot" style in the original TDD book. I say "affect" because they're not idiots, and I find the tone annoying. But I can see why they do it. It's an educational tactic to say "see, I make dumb mistakes too". They advocate a way of making software that embraces dumb mistakes as part of the process and encourages people to get over the fear of looking like an idiot. Underlying that is a psychological view of software development that can be traced back to Weinberg's "egoless programming".
I may be way off base because I haven't read the posts. I tried once and quickly lost interest. But I do think I recognize the culture.
"I agree that there is a serious criticism here, and that sufficiently deep thinking is underrated."
Exactly. The criticism of TDD is (or should be, imo) about the "Driven" part, not so much the "Tests" part. Using conformance to an increasing number of tests as a hill climbing metric and a substitute for deep thinking(sometimes expressed as the "TDD is not about testing, it is about design") gets you stuck on local minima, a point Peter Seibel delineates clearly in his blog post on the subject .
I do disagree with you somewhat in that I think Ron Jeffries ( and most of the Agile evangelist/conference speaker/methodology-book-author types for that matter) are dishonest gurus who couldn't code their way out of a paper bag, but reasonable people can disagree here.
While I find Jeffries's attempt to make a sudoku solver with TDD a bit embarrassing, he's still done more to contribute to the debate than people who are standing on the sidelines being smug (or posting snarky comments on github). I admire his openness and humility.
Also, it's another example of iterative change causing something to go in circles around a local maxima. One issue with TDD is that this can still feel like progress - your tests are still changing from red to green, after all.