ci: Re-enable testing with optimizations enabled

Also, skip a few tests that only work with docstrings enabled.

Fixes matplotlib#10312

Author: QuLogic

.github/workflows/tests.yml

@@ -60,6 +60,7 @@ jobs:
             extra-requirements: '-r requirements/testing/extra.txt'
             # https://github.com/matplotlib/matplotlib/issues/29844
             pygobject-ver: '<3.52.0'
+            python-optimize: 'true'
           - name-suffix: "(Extra TeX packages)"
             os: ubuntu-22.04
             python-version: '3.13'
@@ -330,6 +331,9 @@ jobs:
           if [[ "${{ matrix.python-version }}" == '3.13t' ]]; then
             export PYTHON_GIL=0
           fi
+          if [[ "${{ matrix.python-optimize }}" == 'true' ]]; then
+            export PYTHONOPTIMIZE=2
+          fi
           pytest -rfEsXR -n auto \
             --maxfail=50 --timeout=300 --durations=25 \
             --cov-report=xml --cov=lib --log-level=DEBUG --color=yes

lib/matplotlib/tests/test_artist.py

@@ -1,5 +1,6 @@
 import io
 from itertools import chain
+import sys
 
 import numpy as np
 
@@ -256,7 +257,9 @@ def test_setp():
     # Check *file* argument
     sio = io.StringIO()
     plt.setp(lines1, 'zorder', file=sio)
-    assert sio.getvalue() == '  zorder: float\n'
+    # With optimization, docstrings are stripped so the automated types don't work.
+    expected = 'unknown' if sys.flags.optimize >= 2 else 'float'
+    assert sio.getvalue() == f'  zorder: {expected}\n'
 
 
 def test_None_zorder():
@@ -361,6 +364,8 @@ def set_myparam2(self, val):
     assert 'myparam2' in MyArtist2.set.__doc__
 
 
+@pytest.mark.skipif(sys.flags.optimize >= 2,
+                    reason='Python optimization is enabled and docstrings are stripped')
 def test_set_is_overwritten():
     """set() defined in Artist subclasses should not be overwritten."""
     class MyArtist3(martist.Artist):

lib/matplotlib/tests/test_matplotlib.py

@@ -45,6 +45,8 @@ def test_importable_with_no_home(tmp_path):
         env={**os.environ, "MPLCONFIGDIR": str(tmp_path)}, check=True)
 
 
+@pytest.mark.skipif(sys.flags.optimize >= 2,
+                    reason='Python optimization is enabled and docstrings are stripped')
 def test_use_doc_standard_backends():
     """
     Test that the standard backends mentioned in the docstring of

lib/matplotlib/tests/test_preprocess_data.py

@@ -39,23 +39,25 @@ def func_no_ax_args(*args, **kwargs): pass
     # this has "enough" information to do all the replaces
     _preprocess_data(replace_names=["x", "y"])(func_args)
 
-    # no positional_parameter_names but needed due to replaces
-    with pytest.raises(AssertionError):
-        # z is unknown
-        _preprocess_data(replace_names=["x", "y", "z"])(func_args)
-
     # no replacements at all -> all ok...
     _preprocess_data(replace_names=[], label_namer=None)(func)
     _preprocess_data(replace_names=[], label_namer=None)(func_args)
     _preprocess_data(replace_names=[], label_namer=None)(func_kwargs)
     _preprocess_data(replace_names=[], label_namer=None)(func_no_ax_args)
 
-    # label namer is unknown
-    with pytest.raises(AssertionError):
-        _preprocess_data(label_namer="z")(func)
+    # No asserts with optimizations.
+    if sys.flags.optimize < 1:
+        # no positional_parameter_names but needed due to replaces
+        with pytest.raises(AssertionError):
+            # z is unknown
+            _preprocess_data(replace_names=["x", "y", "z"])(func_args)
+
+        # label namer is unknown
+        with pytest.raises(AssertionError):
+            _preprocess_data(label_namer="z")(func)
 
-    with pytest.raises(AssertionError):
-        _preprocess_data(label_namer="z")(func_args)
+        with pytest.raises(AssertionError):
+            _preprocess_data(label_namer="z")(func_args)
 
 
 @pytest.mark.parametrize('func', all_funcs, ids=all_func_ids)
@@ -193,6 +195,8 @@ def func(ax, x, y, z=1):
         func(None, "a", "b", "z", "z", data=data)
 
 
+@pytest.mark.skipif(sys.flags.optimize >= 2,
+                    reason='Python optimization is enabled and docstrings are stripped')
 def test_docstring_addition():
     @_preprocess_data()
     def funcy(ax, *args, **kwargs):