You probably don't want to run many of these tests under TestDriven.Net, NCrunch, .Net Demon, or any other automatic red/green TDD runner. In fact, since its a 3rd party library, I'm not sure why you would run them. I would add them to your exclusion list.
@jperraud is correct, you cannot unload R from a .Net process since it is unmanaged.
@jperraud is correct, you cannot unload R from a .Net process since it is unmanaged.