Nick Coghlan <ncoghlan@gmail.com> added the comment: Just noting for the record that the reason a new warning wasn't needed here is because there is already a general "No compatibility guarantees" warning for the entire test package: https://docs.python.org/3/library/test.html Thanks for getting this resolved! ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue18578> _______________________________________