If pty is going to work at all then it should work regardless of whether the tests themselves are being run under a tty, yes.

I personally would not want to merge a test based on making isatty lie, because the point of tests is to increase confidence that things work, and that test sounds more complicated and error prone than the original code being tested. I'm not a cpython committer though...

I am more concerned that isatty might actually just not work on windows, since it is actually strictly speaking true that you never have a "try" on Windows, even if you might have a gui console window open. It would be a good idea to check this quickly...

The other option would be to just remove the isatty check from the patch entirely -- it wasn't something that had strong consensus in the first place.