It's all the rage nowadays. "Everyone" recommends it. That in and of itself makes me suspicious.
What are some disadvantages you have found when doing test-first (test-driven) development? I'm looking for personal experiences from knowledgeable practitioners–I can read the hypothetical musings of a hundred wannabes elsewhere on the internet.
I ask not because I am looking to hate TDD, but because it is my job to improve software development process, and the more we can learn about the problems people encounter, the better chance we have of improving the process.
Best Answer
There are quite a few, but the advantages far outweigh the disadvantages.
There's a steep learning curve.
Many developers seem to expect that they can be efficient with test-first programming right from day one. Unfortunately it takes a lot of time to gain experience and program at the same speed as before. You can't get around it.
To be more specific, it's very easy to get wrong. You can very easily (with very good intentions) end up writing a whole bunch of tests which are either difficult to maintain or testing the wrong stuff. It's difficult to give examples here - these kind of issues simply take experience to solve. You need to have a good feel of separating concerns and designing for testability. My best advice here would be to do pair-programming with someone who knows TDD really well.
You do more coding up front.
Test-first means you can't skip tests (which is good) and means you'll end up writing more code up front. This means more time. Again, you can't get around it. You get rewarded with code that's easier to maintain, extend and generally less bugs, but it takes time.
Can be a tough sell to managers.
Software managers are generally only concerned with timelines. If you switch to test-first programming and you're suddenly taking 2 weeks to complete a feature instead of one, they're not gonna like it. This is definitely a battle worth fighting and many managers are enlightened enough to get it, but it can be a tough sell.
Can be a tough sell to fellow developers.
Since there's a steep learning curve not all developers like test-first programming. In fact, I would guess that most developers don't like it at first. You can do things like pair-programming to help them get up to speed, but it can be a tough sell.
In the end, the advantages outweigh the disadvantages, but it doesn't help if you just ignore the disadvantages. Knowing what you're dealing with right from the start helps you to negotiate some, if not all, of the disadvantages.