What are some c# projects to look at for good implementation of unit tests?

Not something too large, yet no 2+2=4 type of examples either. Specifically it would be nice if it were WPF and MVVM. I'm confused on what to test for the view model.

How do you test what is in Lambda's? Do you? Do you make a function public just so you can test it. Or do you just test the final result?