pytest: ignore cython files #33560
Description
As we probably don't want people to write pytests in Cython, we should skip collecting cython files to prevent issues like
$ ./sage -t src/sage/symbolic/expression.pyx
[...]
============================================================================================================ test session starts ============================================================================================================
platform darwin -- Python 3.10.2, pytest-7.0.1, pluggy-1.0.0
rootdir: /Users/mkoeppe/s/sage/sage-rebasing/worktree-gcc11/src, configfile: tox.ini
collected 0 items
=========================================================================================================== no tests ran in 0.01s ===========================================================================================================
ERROR: not found: /Users/mkoeppe/s/sage/sage-rebasing/worktree-gcc11/src/sage/symbolic/expression.pyx
Later, one could use https://github.com/lgpage/pytest-cython to extract doctests from cython files.
Depends on #33572
CC: @mkoeppe
Component: doctest framework
Author: Tobias Diez
Branch/Commit: 4c0ff54
Reviewer: Matthias Koeppe
Issue created by migration from https://trac.sagemath.org/ticket/33560