Lots of Test Projects

This might be a trivial thing, and I might be stupid for not having done with it all my life, but this was a big insight for me. Only a few months ago, I really started making lots of small test projects to only test out a specific feature or solution. For example, I have a project that implements UITableViewCells with XIBs, a test project for working with local notifications, a test project to play around with rotation events and more. By doing these tests in a separate project, I get the following two advantages:

Lower barrier to testing the new feature

Sometimes when I want to test out a new feature in one of my apps I get held back by the fact that it might be complicated to implement. My code will get cluttered and I have to wade through lots of old code. I need to do lots of integration before I can even test it. This allows me to focus on the feature first and integrate it once I’m happy with it.

Future Reference

Having these test projects around is great for future reference. The feature or solution is implemented on its own, so when I want to use it in a different project I don’t have to separate it out from the rest of the code.

Question

Do you have any test projects? How do you organize code for future reference? Keep a notebook? Just dig into old projects? Grep your repos? Discuss at Hacker News.