Hello! 

I've been working on a PR (https://github.com/yt-project/yt/pull/2286) that converts yt's testing framework from nose to pytest. I believe that it's mostly ready to go, so I was writing to see what everyone's thoughts on this change are, if there is any feedback on my implementation, and if anyone would be willing to help review it, since there are quite a few changes. Thanks, and have a good weekend!

-Jared