Unit tests on Mac should fall back to use X if DISPLAY is set

[smontanaro]

Bug report

Bug description:

When running the test suite on my Mac, it always complains I don't have an OS X gui process running. I don't know how to remedy that, but I do know that I have XQuartz running, as the DISPLAY environment variable is set. The test suite should fall back to using X for tkinter and ttk unit tests if available.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-123155: On Darwin, fall back to X if DISPLAY is set #123156

[smontanaro]

Changed the title. XQuartz isn't really required. Any valid DISPLAY setting should be fine.

[ronaldoussoren]

Some questions:

• What version of macOS do you use?

• How did you install Tcl/Tk?

• How do you run the tests?

[ronaldoussoren]

This is a duplicate of #61698.

[smontanaro]

I'm beginning to think that my superpower is proposing half-baked ideas which motivate other people to actually develop/produce/confirm the correct solution to the problem. ;-)

I trust that fix you had me check will find its way into main and 3.13?