Test in Docker with Alpine Linux on CI

.github/workflows/alpine-test.yml

@@ -0,0 +1,72 @@
+name: test-alpine
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    container:
+      image: alpine:latest
+
+    defaults:
+      run:
+        shell: sudo -u runner sh -exo pipefail {0}
+
+    steps:
+    - name: Prepare Alpine Linux
+      run: |
+        apk add sudo git git-daemon python3 py3-pip
+        echo 'Defaults env_keep += "CI GITHUB_* RUNNER_*"' >/etc/sudoers.d/ci_env
+        addgroup -g 127 docker
+        adduser -D -u 1001 runner
+        adduser runner docker
+      shell: sh -exo pipefail {0}  # Run this as root, not the "runner" user.
+
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Set workspace ownership
+      run: |
+        chown -R runner:docker -- "$GITHUB_WORKSPACE"
+      shell: sh -exo pipefail {0}  # Run this as root, not the "runner" user.
+
+    - name: Prepare this repo for tests
+      run: |
+        ./init-tests-after-clone.sh
+
+    - name: Set git user identity and command aliases for the tests
+      run: |
+        git config --global user.email "travis@ci.com"
+        git config --global user.name "Travis Runner"
+        # If we rewrite the user's config by accident, we will mess it up
+        # and cause subsequent tests to fail
+        cat test/fixtures/.gitconfig >> ~/.gitconfig
+
+    - name: Set up virtualenv
+      run: |
+        python -m venv .venv
+        . .venv/bin/activate
+        printf '%s=%s\n' 'PATH' "$PATH" 'VIRTUAL_ENV' "$VIRTUAL_ENV" >>"$GITHUB_ENV"
+
+    - name: Update PyPA packages
+      run: |
+        # Get the latest pip, wheel, and prior to Python 3.12, setuptools.
+        python -m pip install -U pip $(pip freeze --all | grep -ow ^setuptools) wheel
+
+    - name: Install project and test dependencies
+      run: |
+        pip install ".[test]"
+
+    - name: Show version and platform information
+      run: |
+        uname -a
+        command -v git python
+        git version
+        python --version
+        python -c 'import os, sys; print(f"sys.platform={sys.platform!r}, os.name={os.name!r}")'
+
+    - name: Test with pytest
+      run: |
+        pytest --color=yes -p no:sugar --instafail -vv

test/test_util.py

@@ -51,7 +51,9 @@ def permission_error_tmpdir(tmp_path):
     # Set up PermissionError on Windows, where we can't delete read-only files.
     (td / "x").chmod(stat.S_IRUSR)
 
-    # Set up PermissionError on Unix, where we can't delete files in read-only directories.
+    # Set up PermissionError on Unix, where non-root users can't delete files in
+    # read-only directories. (Tests that rely on this and assert that rmtree raises
+    # PermissionError will fail if they are run as root.)
     td.chmod(stat.S_IRUSR | stat.S_IXUSR)
 
     yield td