>Without the tests, I'd have been scratching my head for ages figuring out "what" wasn't working.
The real question though is how all that time you spent writing the tests compares to the time you'd have spent troubleshooting.
The real question though is how all that time you spent writing the tests compares to the time you'd have spent troubleshooting.
The number of crazy edge cases that have been picked up by my tests that would have just "got through" before scares me when looking at code without tests.
Of course, I acknowledge it's not for everyone and it's not for every project. If you have a very strong up-front design and speccing process coupled with a final integration testing process, I'd argue unit testing might not be necessary at all. As a lone developer with a lot to keep in his head, though, unit testing has been very useful.
There was an article published in the last few weeks which showed that teams who write tests spend 10-15% longer in the development process, but they also save 25-30% of the development process time by not having to fix regression defects. Unfortunately, I don't remember which site it was linked from or what the article's title was. If I can find it, I'll link it here.
Rails is a good example where this sync stuff is hard. It's wicked easy to use things like associations and named scopes to query records while forgetting to write a test to ensure that those queries actually return what you specify.
But keep in mind that tests aren't just for you. They're for your team, and the next guy who follows you. You can learn a lot about intent from tests too.