Debug MEF

Nice article about debugging MEF

http://ihadthisideaonce.com/2012/01/31/stop-guessing-about-mef-composition-and-start-testing/

And would it be nice if you can run composition testing?
here is sample example how to do this:
http://ihadthisideaonce.com/2012/06/12/mef-composition-tests-redux/