Add Coverage workflow

.github/workflows/ci.yml

@@ -66,14 +66,41 @@ jobs:
           python-version: ${{ matrix.python-version }}
           allow-prereleases: true
 
-      - name: Test typing_extensions
+      - name: Install coverage
+        if: ${{ !startsWith(matrix.python-version, 'pypy') }}
+        run: |
+          # Be wary that this does not install typing_extensions in the future
+          pip install coverage
+
+      - name: Test typing_extensions with coverage
+        if: ${{ !startsWith(matrix.python-version, 'pypy') }}
+        run: |
+          # Be wary of running `pip install` here, since it becomes easy for us to
+          # accidentally pick up typing_extensions as installed by a dependency
+          cd src
+          python --version  # just to make sure we're running the right one
+          # Run tests under coverage
+          export COVERAGE_FILE=.coverage_${{ matrix.python-version }}
+          python -m coverage run -m unittest test_typing_extensions.py
+      - name: Test typing_extensions no coverage on pypy
+        if: ${{ startsWith(matrix.python-version, 'pypy') }}
         run: |
           # Be wary of running `pip install` here, since it becomes easy for us to
           # accidentally pick up typing_extensions as installed by a dependency
           cd src
           python --version  # just to make sure we're running the right one
           python -m unittest test_typing_extensions.py
 
+      - name: Archive code coverage results
+        if: ${{ !startsWith(matrix.python-version, 'pypy') }}
+        uses: actions/upload-artifact@v4
+        with:
+          name: .coverage_${{ matrix.python-version }}
+          path: ./src/.coverage*
+          include-hidden-files: true
+          compression-level: 0 # no compression
+
+
       - name: Test CPython typing test suite
         # Test suite fails on PyPy even without typing_extensions
         if: ${{ !startsWith(matrix.python-version, 'pypy') }}
@@ -111,3 +138,45 @@ jobs:
               title: `Daily tests failed on ${new Date().toDateString()}`,
               body: "Runs listed here: https://github.com/python/typing_extensions/actions/workflows/ci.yml",
             })
+  prepare-report-coverage:
+    name: Report coverage
+
+    runs-on: ubuntu-latest
+
+    needs: [tests]
+
+    if: ${{ always() }}
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3"
+      - name: Download coverage artifacts
+        uses: actions/download-artifact@v4
+        with:
+          pattern: .coverage_*
+          path: .
+          # merge only when files are named differently
+          merge-multiple: true
+      - name: Install dependencies
+        run: pip install coverage
+      - name: Combine coverage results
+        run: |
+          # List the files to see what we have
+          echo "Combining coverage files..."
+          ls -aR .coverage*
+          coverage combine .coverage*
+          echo "Creating coverage report..."
+          coverage report
+          coverage xml
+
+      - name: Archive code coverage report
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage
+          path: coverage.xml
+          compression-level: 0 # no compression

.github/workflows/coverage_report.yml

@@ -0,0 +1,85 @@
+name: Add coverage comment on PR
+
+on:
+  workflow_run:
+    workflows: ["Test and lint"]
+    types:
+      - completed
+
+permissions: {}
+
+jobs:
+  get-pr-number:
+    runs-on: ubuntu-latest
+    permissions: {}
+    if: >
+      github.event.workflow_run.event == 'pull_request'
+      && github.repository == github.event.workflow_run.repository.full_name
+    # The github.repository == ... check will prevent this workflow from running on forks.
+    steps:
+      - name: Get PR number
+        id: get_pr_number
+        env:
+          SHA: "${{ github.event.workflow_run.head_sha }}"
+          REPO: "${{ github.repository }}"
+        run: |
+          # Query GitHub API to find the PR number associated with the head commit SHA
+          PR_DATA=$(curl -s "https://api.github.com/search/issues?q=repo:$REPO+type:pr+sha:$SHA")
+          # Check if head commit is on a single PR else ambiguous which PR triggered the workflow
+          ITEMS_COUNT=$(jq '.items | length' <<< "$PR_DATA")
+          if [ "$ITEMS_COUNT" -ne 1 ]; then
+            echo "Error: Expected exactly one PR, but found $ITEMS_COUNT." >&2
+            exit 1
+          fi
+          PR_NUMBER=$(jq '.items[0].number' <<< "$PR_DATA")
+          echo "pr_number=$PR_NUMBER" >> $GITHUB_OUTPUT
+    outputs:
+      pr_number: ${{ steps.get_pr_number.outputs.pr_number }}
+
+  create-md-comment:
+    runs-on: ubuntu-latest
+    permissions: {}
+    if: >
+      github.event.workflow_run.event == 'pull_request'
+      && github.repository == github.event.workflow_run.repository.full_name
+    steps:
+      - name: Download coverage report
+        uses: actions/download-artifact@v4
+        with:
+          name: coverage
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          run-id: ${{ github.event.workflow_run.id }}
+      - name: Code Coverage Report
+        uses: irongut/CodeCoverageSummary@51cc3a756ddcd398d447c044c02cb6aa83fdae95 # v1.3.0
+        with:
+          filename: coverage.xml
+          badge: true
+          fail_below_min: false
+          format: markdown
+          hide_branch_rate: false
+          hide_complexity: true
+          indicators: true
+          output: both
+          thresholds: '80 90'
+      - name: Upload coverage summary
+        uses: actions/upload-artifact@v4
+        with:
+          name: code-coverage-results
+          path: code-coverage-results.md
+  post-comment:
+    runs-on: ubuntu-latest
+    needs: [get-pr-number, create-md-comment]
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Download coverage report
+        uses: actions/download-artifact@v4
+        with:
+          name: code-coverage-results
+      - name: Add Coverage PR Comment
+        uses: marocchino/sticky-pull-request-comment@52423e01640425a022ef5fd42c6fb5f633a02728  # v2.9.3
+        with:
+          recreate: true
+          path: code-coverage-results.md
+          number: ${{ needs.get-pr-number.outputs.pr_number }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -16,3 +16,6 @@ venv*/
 *.swp
 *.pyc
 *.egg-info/
+
+.coverage*
+coverage.xml

pyproject.toml

@@ -120,3 +120,10 @@ ignore = [
 [tool.ruff.lint.isort]
 extra-standard-library = ["tomllib"]
 known-first-party = ["typing_extensions", "_typed_dict_test_helper"]
+
+[tool.coverage.report]
+show_missing = true
+# Omit files that are created in temporary directories during tests.
+# If not explicitly omitted they will result in warnings in the report.
+omit = ["inspect*", "ann*"]
+ignore_errors = true