Do Not Unit Test Third Party Frameworks

I'm stealing today's tip from Brendan Enrick. He has written a series of blog posts on tips for unit testing. In one of them, he talks about unit testing with third party frameworks:
Make sure that what you're testing is part of your code and not someone else's. If you're testing code you have no access to you better not be keeping that around as an automated test. You're wasting your time if you're creating automated tests for this code. If you find a bug in the code you can tell someone about it, but you probably can't fix the code. If it is an open source project you're testing then go test the code in their test library and fix issues you find. You will be doing them and yourself a favor. Don't clutter your own test library.

You can checkout the rest of that post here. At the bottom you'll see links to other posts he's done on the topic.
Unit TestingMichael Kelly