You have to use sys.platform to get 'darwin', not os.name. The rest of
the test seems good.

I didn't spot the check of EEXIST in pyepoll_internal_ctl, I'm not sure
it's a good idea. I understand it's for being able to only use register,
but it's not the way it's meant to be used. At least, there should be a
test for it.

Your example in kqueue_queue_doc doesn't work:
 * it uses KQ_ADD instead of KQ_EV_ADD
 * on OS X, you can't use kqueue on stdin
 * it uses KQ_DELETE instead of KQ_EV_DELETE
Maybe an example on an arbitrary fd would be better.

FWIW, I would have prefer to review epoll wrapper first, then kqueue.
Splitting functionalities makes it easier to review.  But that will be
great to have that in python :).