Unit testing through the UI

One of my readers asked whether there were any UI unit testing tools.

While I have seen some ASP.net tools like this, in general I'd expect that you would unit test a UI by making the UI a very thin layer (one that doesn't really need testing), and writing the unit tests to talk to the layer underneath.

Though I haven't had the opportunity to try it on a full project, I think that Presenter First has a lot going for it.