TST: skip a docstring-focused test when running in Python's optimized mode - #17478

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👋 Thank you for your draft pull request! Do you know that you can use [ci skip] or [skip ci] in your commit messages to skip running continuous integration tests until you are ready?

What is the purpose of the change here? If you are running the tests at an optimization level that discards docstrings then you are also running at an optimization level that discards assert statements, so trying to access the docstrings can't cause problems.

@eerovaher - pytest assert are not affected by optimization - another bit of pytest magic - it rewrites the assert upon import of the test module - https://docs.pytest.org/en/stable/announce/release-2.1.0.html and https://docs.pytest.org/en/stable/how-to/assert.html#assert-details. (Discovered this in numpy/numpy#27868)

pytest assert are not affected by optimization

yes. I'm only addressing actual issues that I discover while actually running pytest with PYTHONOPTIMIZE=2, I'm not trying to guess what could be wrong.

I can't run the tests with optimizations at all (with pytest 8.3.2)

$ PYTHONOPTIMIZE=1 pytest astropy/time/tests/test_sidereal.py
Traceback (most recent call last):
  ...
pytest.PytestConfigWarning: assertions not in test modules or plugins will be ignored because
assert statements are not executed by the underlying Python interpreter (are you using python -O?)

yes, one also needs to ignore this specific warning in pytest's configuration, which is annoying to do since you also have to know what builtin warning type PytestConfigWarning derives from.
I use this patch to run tests:

diff --git a/pyproject.toml b/pyproject.toml
index b2dea87895..985b3ef455 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -221,6 +221,7 @@ filterwarnings = [
     "error",
     "ignore:unclosed <socket:ResourceWarning",
     "ignore:unclosed <ssl.SSLSocket:ResourceWarning",
+    "ignore:assertions not in test modules or plugins will be ignored:UserWarning"
 ]
 doctest_norecursedirs = [
     "*/setup_package.py",