Test Driven Development in PHP

I've used both PHPUnit & SimpleTest and I found SimpleTest to be easier to use.

As far as TDD goes, I haven't had much luck with it in the purest sense. I think that's mainly a time/discipline issue on my part though.

Adding tests after the fact has been somewhat useful but my favorite things to do is use write SimpleTest tests that test for specific bugs that I have to fix. That makes it very easy to verify that things are actually fixed and stay fixed.

I highly recommend Test-Driven Development by Kent Beck (ISBN-10: 0321146530). It wasn't written specifically for PHP, but the concepts are there and should be easily translatable to PHP.

PHPUnit is a standard, but it's sometimes also overwhelming, so if you find it too complex, check out phpt to get you started. It's very, very easy to write tests in it. A no brainer for any programmer.

And to answer your TDD question - I am not sure if TDD is widley used in the PHP space. I can see that rapid application development and TDD somewhat clash (strictly IMHO). TDD requires you to have the complete picture of what you build and you write your tests up front and then implement the code to make the test pass.

So for example what we do instead, is to write a lot of tests when we are done. This is not always the best approach because you sometimes end up with bogus tests that pass, but are not really useful but at least it's something you can expand on. Internally we continue on tests and basically write a test for each bug we find. This is how it becomes more solid.