ci: oneshot-test: create an artifact out of failed tests

Create an artifact out of failed tests, which allows us to inspect them
(the frozen application itself and the build directory with .toc files
and xref.html for debugging import chains).

Author: rokm

.github/workflows/oneshot-test.yml

@@ -139,7 +139,8 @@ jobs:
 
     # Finally, the usual: setup Python, install dependencies, test.
     steps:
-      - uses: actions/checkout@v6
+      - name: Checkout pyinstaller-hooks-contrib code
+        uses: actions/checkout@v6
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v6
@@ -169,5 +170,55 @@ jobs:
           # Install PyInstaller
           pip install ${{ github.event.inputs.pyinstaller }}
 
+      # Relocate the temporary directory to a fixed location so we can
+      # generate artifacts out of failed tests.
+      - name: Relocate temporary dir
+        shell: bash
+        run: |
+          echo "PYTEST_DEBUG_TEMPROOT=$RUNNER_TEMP" >> $GITHUB_ENV
+
       - name: Run tests
+        id: run-tests
         run: pytest -v -n logical ${{ inputs.pytest_args }}
+
+      # On all platforms, create a tarball to ensure that symlinks are preserved.
+      # Avoid using compression here, as the tarball will end up collected into
+      # artifact zip archive. To simplify this across platforms, run this step
+      # in python and use python's tarfile module.
+      - name: Archive failed tests
+        if: ${{ failure() && steps.run-tests.outcome == 'failure' }}
+        shell: python
+        run: |
+          import os
+          import sys
+          import tarfile
+
+          try:
+            import getpass
+            user = getpass.getuser() or "unknown"
+          except Exception:
+            user = "unknown"
+
+          temproot = os.environ['PYTEST_DEBUG_TEMPROOT']
+
+          pytest_name = f'pytest-of-{user}'
+          pytest_fullpath = os.path.join(temproot, pytest_name)
+          print(f"Input directory: {pytest_fullpath}!", file=sys.stderr)
+
+          output_file = os.path.join(temproot, 'archived-failed-tests.tar')
+          print(f"Output file: {output_file}!", file=sys.stderr)
+
+          assert os.path.isdir(pytest_fullpath)
+          assert not os.path.exists(output_file)
+
+          with tarfile.open(output_file, "w") as tf:
+            tf.add(pytest_fullpath, arcname=pytest_name, recursive=True)
+
+          print(f"Created {output_file}!", file=sys.stderr)
+
+      - name: Create artifact out of archived failed tests
+        if: ${{ failure() && steps.run-tests.outcome == 'failure' }}
+        uses: actions/upload-artifact@v6
+        with:
+          name: failed-tests-${{ matrix.os }}-python-${{ matrix.python-version }}
+          path: '${{ env.PYTEST_DEBUG_TEMPROOT }}/archived-failed-tests.tar'