(archived from my old blog from my pre-MS days)
One of the great things about ALT.NET is the variety of choices it affords. However, this can also become an albatross around your neck when trying to choose a particular unit testing framework, mocking framework, IoC container, etc. I mean, if you haven't tried most if not all of the choices, then you don't know what you're missing. Of course you can read about the different options out there, but that's no substitute for trying them out for yourself. Having said that, there's still a lot of utility in reading about them to exploit them to your advantage. Thus, I recently moved out of my normal comfort-zone, (NUnit, Rhino.Mocks, Windsor Container) and tried some other technologies.
What follows is a short description of my impression of a couple of Unit Testing frameworks that I've played with in the past couple of weeks. Note that this is not intended to be an complete portrayal of each tool, but rather how I felt when attempting to use them.
This is the old standby, but there's a 2.5 alpha that I hadn't tried. I liked a lot of the changes that have gone into it, but found that too many things that I depend on for integrating with NUnit don't work with 2.5 yet.
I like XUnit. It's simple. ALT.NET takes a bad rap for being hard to adopt, so one thing I try to emphasize is simplicity. This is XUnit's strength. If I were starting someone off in Unit Testing, I'd tell them to look at XUnit. I have to admit that I do like the Constraint model in NUnit, however. It just reads more naturally. Also, pretty much everything works with NUnit, but not necessarily with XUnit (like TeamCity, currently). So eventually, I went back to NUnit 2.4.8. It worked fine with TestDriven.NET, however.
So the moral of the story is that software (including OSS) has momentum. Once you get used to a certain way of development, it feels painful to switch, even if the other applications have some nice new features.
Conspicuously missing here is MbUnit, which I've tried in the past but again went back to NUnit eventually. I'll have to try it out again soon.