Add Coverage workflow

.github/workflows/ci.yml

@@ -64,14 +64,41 @@ 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: ${{ !startsWith(matrix.python-version, 'pypy') }}
+        run: |
+          # Be wary of running `pip install` here, since it becomes easy for us to
+          # accidentally pick up typing_extensions as installed by a dependency
+          cd src
+          python --version  # just to make sure we're running the right one
+          export COVERAGE_FILE=.coverage_${{ matrix.python-version }}
+          # Run with coverage omit files that are executed in tempfiles
+          coverage run --omit ann_module*,inspect* -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') }}
@@ -109,3 +136,61 @@ jobs:
               title: `Daily tests failed on ${new Date().toDateString()}`,
               body: "Runs listed here: https://github.com/python/typing_extensions/actions/workflows/ci.yml",
             })
+
+  report-coverage:
+    name: Report coverage
+
+    runs-on: ubuntu-latest
+
+    needs: [tests]
+    permissions:
+      contents: read
+      pull-requests: write
+
+
+    if: ${{ always() }}
+
+    steps:
+      - uses: actions/checkout@v4
+      - 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:"
+          coverage combine --data-file=.coverage .coverage*
+          # add -i to ignore parsed code of temp files.
+          coverage report -i -m
+          coverage xml -i
+
+      - name: Code Coverage Report
+        uses: irongut/[email protected]
+        with:
+          # Alternatively use one file per python version
+          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: Add Coverage PR Comment
+        uses: marocchino/sticky-pull-request-comment@v2
+        if: github.event_name == 'pull_request'
+        with:
+          recreate: true
+          path: code-coverage-results.md

.gitignore

@@ -16,3 +16,5 @@ venv*/
 *.swp
 *.pyc
 *.egg-info/
+
+.coverage*

src/test_typing_extensions.py

@@ -6887,6 +6887,7 @@ def test_typing_extensions_compiles_with_opt(self):
             self.fail('Module does not compile with optimize=2 (-OO flag).')
 
 
+
 class CoolEmployee(NamedTuple):
     name: str
     cool: int