I would actually prefer going the other way -- change the remaining self.assertEqual(x, y) calls to assert x == y. I mostly run the tests using py.test and it much prefers the latter idiom.

Does anyone routinely run the stdlib tests with -O?

OK, I concede your point (even though I don't like noisy commits -- you will end up owning all those lines in hg/git blame forever). Once this is merged here, can you take care of merging it into 3.5+3.6?

My ownership of the lines is unfortunate, agreed.

Yes, I can sync cpython after merge here.

Note that, once #136 is resolved, most issubclass assertions will have to be changed again.

OK, go ahead and merge into CPython 3.5 and 3.6.

Thanks, Guido. I've merged into cpython 3.5 and default.

The only remaining question is whether you want python2/test_typing.py similarly treated. I have no opinion about it, but am willing to put forth the effort to do it if you want to keep the diff between src and python2 smaller.

Yea, please do the python2/test_typing.py -- I do try to keep them in sync. And there are plenty of PRs coming up.