gh-111735: Skip turtle doctests when _tkinter is not available

[StanFromIreland]

Most of these were fixed by 859c068, I presume these were added after when the CI built with tkinter so it wasn't caught.

• Issue: Doc/library/turtle.rst doctests are failing when tkinter is not present #111735

[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #34241299 | 📁 Comparing 864063d against main (f54fd2a)

  🔍 Preview build  

1 file changed

± library/turtle.html

[terryjreedy]

My comments on the previous PR might or might not apply. I have not interacted with doctests since then.

[StanFromIreland]

I saw your previous comments @terryjreedy , and I don't think that they apply here.

• gh-111735: Fix turtle.rst doctests when tkinter is not present #111736 (comment): I don't see a reason to add support for vanilla doctest when Sphinx's doctest does the job here.
• gh-111735: Fix turtle.rst doctests when tkinter is not present #111736 (comment): It doesn’t, it's specific to that one directive.
• gh-111735: Fix turtle.rst doctests when tkinter is not present #111736 (comment): It hides the codeblock in the rendered docs, it's only there for testing purposes.

[terryjreedy]

After 859c068 Doc/conf.py:24 sets _tkinter to None after import failure. To detect a future regression in local testing, should we add a CI or buildbot test that patches conf.py to _tkinter = None and then runs Sphinx doctest on turtle.rst?

[StanFromIreland]

To detect a future regression in local testing, should we add a CI or buildbot test that patches conf.py to _tkinter = None and then runs Sphinx doctest on turtle.rst?

I think we can leave this to a separate PR. We don't currently have any Buildbots that run any form of docs build, so this would need quite a bit of work in buildmaster-config, as well as someone to sponsor the machine it will run on. Adding it to the CI is also possible. But to be honest, I'm not sure there's a real benefit. Only we (CPython developers) run the doctests, and when we do it's usually with tkinter. I don't think the cost justify protecting against regressions here.