Test-Driven Development is Stupid

Just wait until he has to write a system with several hundred web services that have been documented to perform in a very precise manner given particular data sets, and have hundreds of customers who have integrated to that API, and absolutely required that there be no variance in the output in the API, or there (extraordinarily expensive) system integration will fail, at great costs to their business systems.

I'm not saying TDD makes sense everywhere, but being able to confirm that your 3000+ continuous integration tests all passed green before shipping a new version to all of your customer is a huge way to avoid embarrassingly predictable bugs. (Leaving, of course, the opportunity to ship the embarrassingly non-obvious bugs)

And, honestly, it's not clear that he was opposed to TDD, as he was opposed to being constrained to having to write huge test frameworks during the exploratory phase of code development, in which you may want to have a bit more freedom to write/discard while you feel out requirements/solutions.

Way stronger than I'd write, and I don't agree with it entirely, but the author has a point.

Personally, what annoys me the most about TDD I've seen in the wild are two things: designing for tests instead of actual problems, and tests affecting the structure of "real" code.

Designing for tests - the standard TDD approach, first we write tests, then we write code to pass the tests. Quite often the consideration of the problem being solved disappears. It's a fine approach when your task is to write a small black box that takes some data in and transforms it into something else. But I've never seen a case where someone made it work for complex tasks. It always ends up the same - your tests become more complicated than the tested code. It happens with any non-trivial problem, because the thinking you have to do to write tests that make sense is the same as the thinking you need to do to solve the problem in the first place. So you're basically writing the program twice, only in a convoluted way, and without considerations for global design.

Tests affecting the structure - this is IMO a strong code smell. If you're modifying your design to accomodate for tests, by e.g. adding superfluous dependencies, hooks or injection points, you've screwed up. It only makes the code more complicated and less reliable.

The only tests I've found valuable so far (in terms of effect for effort spent) are regression tests - the ones you write to catch bugs in order to make sure they won't happen again. Everything else in TDD seems to be easily replaceable by proper iterative programming.

Maybe that's why TDD is popular in the languages without a sane REPL.

His experience might be a lot different from mine, but I've found TDD enormously helpful when tackling legacy systems. Maybe that's not "test-driven development" and more like "test-driven refactoring", but working on complex legacy systems where the original developers are basically all gone is scary, and TDD has helped me make some sense of it and feel a lot better about making changes.

> Unit testing ... is not just about developing as it is about preventing regressions.

Absolutely this! Unit testing helps you during the dark years of maintenance phase, when you must fix a bug or add a new feature and you don't have the knowledge, nor the time, to build a full representation of the application in your head: you just touch as little code as possible to get the work done, and unit tests help to ensure that all the rest stays equal.

TDD isn't about writing tests. It's about designing architecture.

http://www.drdobbs.com/tdd-is-about-design-not-testing/22921...