Run tests in parallel with pytest-xdist

.ci/build.sh

@@ -2,6 +2,5 @@
 
 set -e
 
-python3 -m coverage erase
 make clean
 make install-coverage

.ci/install.sh

@@ -24,13 +24,7 @@ sudo apt-get -qq install libfreetype6-dev liblcms2-dev libtiff-dev python3-tk\
 
 python3 -m pip install --upgrade pip
 python3 -m pip install --upgrade wheel
-python3 -m pip install coverage
-python3 -m pip install defusedxml
 python3 -m pip install ipython
-python3 -m pip install olefile
-python3 -m pip install -U pytest
-python3 -m pip install -U pytest-cov
-python3 -m pip install -U pytest-timeout
 # optional test dependencies, only install if there's a binary package.
 python3 -m pip install --only-binary=:all: numpy || true
 python3 -m pip install --only-binary=:all: pyarrow || true

.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

.github/workflows/test-mingw.yml

@@ -74,7 +74,7 @@ jobs:
           pushd depends && ./install_extra_test_images.sh && popd
 
       - name: Build Pillow
-        run: CFLAGS="-coverage" python3 -m pip install .
+        run: CFLAGS="-coverage" python3 -m pip install .[tests]
 
       - name: Test Pillow
         run: |

.github/workflows/test-valgrind-memory.yml

@@ -60,5 +60,10 @@ jobs:
       run: |
         # The Pillow user in the docker container is UID 1001
         sudo chown -R 1001 $GITHUB_WORKSPACE
-        docker run --name pillow_container -e "PILLOW_VALGRIND_TEST=true" -v $GITHUB_WORKSPACE:/Pillow pythonpillow/${{ matrix.docker }}:${{ matrix.dockerTag }} /Pillow/depends/docker-test-valgrind-memory.sh
+        docker run --name pillow_container \
+          -e "PILLOW_VALGRIND_TEST=true" \
+          -e "PYTEST_ADDOPTS=-n0" \
+          -v $GITHUB_WORKSPACE:/Pillow \
+          pythonpillow/${{ matrix.docker }}:${{ matrix.dockerTag }} \
+          bash -c "python3 -m pip install pytest-xdist && /Pillow/depends/docker-test-valgrind-memory.sh"
         sudo chown -R runner $GITHUB_WORKSPACE

.github/workflows/test-valgrind.yml

@@ -54,5 +54,9 @@ jobs:
       run: |
         # The Pillow user in the docker container is UID 1001
         sudo chown -R 1001 $GITHUB_WORKSPACE
-        docker run --name pillow_container -e "PILLOW_VALGRIND_TEST=true" -v $GITHUB_WORKSPACE:/Pillow pythonpillow/${{ matrix.docker }}:${{ matrix.dockerTag }}
+        docker run --name pillow_container \
+          -e "PILLOW_VALGRIND_TEST=true" \
+          -e "PYTEST_ADDOPTS=-n0" \
+          -v $GITHUB_WORKSPACE:/Pillow \
+          pythonpillow/${{ matrix.docker }}:${{ matrix.dockerTag }}
         sudo chown -R runner $GITHUB_WORKSPACE

Makefile

@@ -62,7 +62,7 @@ install:
 
 .PHONY: install-coverage
 install-coverage:
-	CFLAGS="-coverage -Werror=implicit-function-declaration" python3 -m pip -v install .
+	CFLAGS="-coverage -Werror=implicit-function-declaration" python3 -m pip -v install .[tests]
 	python3 selftest.py
 
 .PHONY: debug
@@ -95,12 +95,6 @@ test:
 	python3 -c "import pytest" > /dev/null 2>&1 || python3 -m pip install pytest
 	python3 -m pytest -qq
 
-.PHONY: test-p
-test-p:
-	python3 -c "import xdist" > /dev/null 2>&1 || python3 -m pip install pytest-xdist
-	python3 -m pytest -qq -n auto
-
-
 .PHONY: valgrind
 valgrind:
 	python3 -c "import pytest_valgrind" > /dev/null 2>&1 || python3 -m pip install pytest-valgrind

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

@@ -70,6 +70,7 @@ optional-dependencies.tests = [
   "packaging",
   "pytest",
   "pytest-cov",
+  "pytest-sugar",
   "pytest-timeout",
   "pytest-xdist",
   "setuptools",
@@ -200,7 +201,10 @@ extra_checks = true
 pretty = true
 
 [tool.pytest]
-addopts = [ "-ra", "--color=auto" ]
+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",
 ]