Comment 39 for bug 1277104

So, IMHO if we're going to enforce this we need to enforce using keyword args for assertEqual. There's no way to automatically enforce the positional form, and there's no way reviewers are going to catch every instance of someone swapping them. There's a slightly better chance of reviewers catching something of the form self.assertEqual(expected=actual, actual=expected) though.

That said, I doubt I will ever trust the expected, actual in test failures anyway, so I really don't care about this. :-)