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

@@ -24,14 +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
-python3 -m pip install pyroma
 # 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 +4,4 @@ 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 --cov PIL --cov Tests --cov-report term --cov-report xml Tests

.github/workflows/test-mingw.yml

@@ -78,7 +78,7 @@ 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

@@ -56,5 +56,10 @@ 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

.github/workflows/test.yml

@@ -53,7 +53,7 @@ jobs:
           "3.10",
         ]
         include:
-        - { python-version: "3.12", PYTHONOPTIMIZE: 1, REVERSE: "--reverse" }
+        - { python-version: "3.12", PYTHONOPTIMIZE: 1 }
         - { python-version: "3.11", PYTHONOPTIMIZE: 2 }
         # Free-threaded
         - { python-version: "3.15t", disable-gil: true }
@@ -123,9 +123,6 @@ jobs:
 
     - name: Test
       run: |
-        if [ $REVERSE ]; then
-          python3 -m pip install pytest-reverse
-        fi
         if [ "${{ matrix.os }}" = "ubuntu-latest" ]; then
           xvfb-run -s '-screen 0 1024x768x24' sway&
           export WAYLAND_DISPLAY=wayland-1
@@ -135,7 +132,6 @@ jobs:
         fi
       env:
         PYTHONOPTIMIZE: ${{ matrix.PYTHONOPTIMIZE }}
-        REVERSE: ${{ matrix.REVERSE }}
 
     - name: Prepare to upload errors
       if: failure()

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
@@ -97,12 +97,6 @@ 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/test_file_avif.py

@@ -772,6 +772,7 @@ def test_seek_errors(self) -> None:
 MAX_THREADS = os.cpu_count() or 1
 
 
+@pytest.mark.xdist_group(name="leak-group")
 @skip_unless_feature("avif")
 class TestAvifLeaks(PillowLeakTestCase):
     mem_limit = MAX_THREADS * 3 * 1024

Tests/test_imagegrab.py

@@ -12,6 +12,7 @@
 from .helper import assert_image_equal_tofile, skip_unless_feature
 
 
+@pytest.mark.xdist_group(name="imagegrab-group")
 class TestImageGrab:
     @pytest.mark.skipif(
         os.environ.get("USERNAME") == "ContainerAdministrator",

pyproject.toml

@@ -73,6 +73,7 @@ optional-dependencies.tests = [
   "pyroma>=5",
   "pytest",
   "pytest-cov",
+  "pytest-sugar",
   "pytest-timeout",
   "pytest-xdist",
   "trove-classifiers>=2024.10.12",
@@ -208,7 +209,7 @@ lint.isort.required-imports = [
 max_supported_python = "3.14"
 
 [tool.pytest.ini_options]
-addopts = "-ra --color=auto"
+addopts = "-ra --color=auto --numprocesses=auto --dist=loadgroup"
 testpaths = [
   "Tests",
 ]