GHA: test windows wheels in Docker

.github/workflows/test-windows.yml

@@ -235,6 +235,20 @@ jobs:
         %pythonLocation%\python.exe -m pip wheel -v -C raqm=vendor -C fribidi=vendor -C imagequant=disable .
       shell: cmd
 
+    - name: Test Wheel
+      if: "github.event_name != 'pull_request' && !contains(matrix.python-version, 'pypy')"
+      run: |
+        cd C:\pillow
+        python -m pip install pytest pytest-timeout
+        for %%f in (dist\*.whl) do python -m pip install %%f
+        reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\python.exe" /v "GlobalFlag" /t REG_SZ /d "0x02000000" /f
+        path C:\pillow\winbuild\build\bin\;%PATH%
+        set CI=
+        python -m pytest -vx Tests\check_wheel.py Tests
+      shell: cmd /c copy {0} docker.bat && docker run --rm -v %GITHUB_WORKSPACE%:C:\pillow %DOCKER_IMAGE% C:\pillow\docker.bat
+      env:
+        DOCKER_IMAGE: winamd64/python:${{ matrix.python-version }}-windowsservercore
+
     - name: Upload wheel
       uses: actions/upload-artifact@v3
       if: "github.event_name != 'pull_request'"

Tests/check_wheel.py

@@ -0,0 +1,24 @@
+import sys
+
+import pytest
+
+from PIL import features
+
+
+@pytest.mark.skipif(sys.platform != "win32", reason="requires Windows")
+def test_windows_wheel_features():
+    expected_modules = ["pil", "tkinter", "freetype2", "littlecms2", "webp"]
+    expected_codecs = ["jpg", "jpg_2000", "zlib", "libtiff"]
+    expected_features = [
+        "webp_anim",
+        "webp_mux",
+        "transp_webp",
+        "raqm",
+        "fribidi",
+        "harfbuzz",
+        "libjpeg_turbo",
+    ]
+
+    assert features.get_supported_modules() == expected_modules
+    assert features.get_supported_codecs() == expected_codecs
+    assert features.get_supported_features() == expected_features

Tests/test_imagegrab.py

@@ -15,6 +15,8 @@ class TestImageGrab:
         sys.platform not in ("win32", "darwin"), reason="requires Windows or macOS"
     )
     def test_grab(self):
+        if os.environ.get("USERNAME", "") == "ContainerAdministrator":
+            pytest.skip("can't grab screen when running in Docker")
         ImageGrab.grab()
         ImageGrab.grab(include_layered_windows=True)
         ImageGrab.grab(all_screens=True)