Hi, generator based tests do not work with the pytest_twisted plugin (at least if you want to pass arguments) http://bitbucket.org/schmir/py-trunk/changeset/20e64b3893a0/ contains a fix. I'm not quite sure if is correct I've also fixed some typos in comments: http://bitbucket.org/schmir/py-trunk/changeset/4796f75ef7c5/ Regards, - Ralf