Run PillowLeakTestCases separetely without xdist

Author: hugovk

.ci/test.sh

@@ -4,4 +4,5 @@ set -e
 
 python3 -c "from PIL import Image"
 
-python3 -bb -m pytest -vv -x -W always --cov PIL --cov Tests --cov-report term --cov-report xml Tests $REVERSE
+python3 -bb -m pytest -vv -x -W always Tests -m "isolated" -n0
+python3 -bb -m pytest -vv -x -W always Tests -m "not isolated" --cov PIL --cov Tests --cov-report term --cov-report xml $REVERSE

Tests/helper.py

@@ -216,6 +216,7 @@ def mark_if_feature_version(
     return pytest.mark.pil_noop_mark()
 
 
+@pytest.mark.isolated
 @pytest.mark.skipif(sys.platform.startswith("win32"), reason="Requires Unix or macOS")
 class PillowLeakTestCase:
     # requires unix/macOS

pyproject.toml

@@ -210,6 +210,9 @@ max_supported_python = "3.14"
 
 [tool.pytest.ini_options]
 addopts = "-ra --color=auto --numprocesses=auto --dist=loadscope"
+markers = [
+  "isolated: tests that are not compatible with pytest-xdist (deselect with '-m \"not isolated\"')",
+]
 testpaths = [
   "Tests",
 ]