🧪 Collect Cython coverage in CI

.coveragerc

@@ -11,6 +11,7 @@ show_missing = true
 [run]
 branch = true
 cover_pylib = false
+plugins = Cython.Coverage
 relative_files = true
 source =
   tests

.github/workflows/ci-cd.yml

@@ -77,6 +77,15 @@ jobs:
     - name: Build sdists and pure-python wheel
       env:
         PIP_CONSTRAINT: requirements/cython.txt
+        YARL_CYTHON_TRACING: >-  # Cython line tracing for coverage collection
+          ${{
+            (
+              github.event_name == 'push'
+              && contains(github.ref, 'refs/tags/')
+            )
+            && '0'
+            || '1'
+          }}
       run: python -Im build --config-setting=--pure-python=true
     - name: Upload built artifacts for testing
       uses: actions/upload-artifact@v3
@@ -109,6 +118,15 @@ jobs:
       os: ${{ matrix.os }}
       source-tarball-name: ${{ needs.pre-setup.outputs.sdist-name }}
       dists-artifact-name: ${{ needs.pre-setup.outputs.dists-artifact-name }}
+      cython-tracing: >-  # Cython line tracing for coverage collection
+        ${{
+          (
+            github.event_name == 'push'
+            && contains(github.ref, 'refs/tags/')
+          )
+          && '0'
+          || '1'
+        }}
 
   test:
     name: Test
@@ -202,6 +220,17 @@ jobs:
       shell: bash
     - name: Self-install
       run: python -Im pip install '${{ steps.wheel-file.outputs.path }}'
+    - name: Produce the C-files for the Coverage.py Cython plugin
+      if: >-  # Only works if the dists were built with line tracing
+        matrix.no-extensions == 'Y'
+        && (
+          github.event_name != 'push'
+          || !contains(github.ref, 'refs/tags/')
+        )
+      run: |
+        set -eEuo pipefail
+        python -Im cython yarl/*.pyx
+      shell: bash
     - name: Run unittests
       env:
         YARL_NO_EXTENSIONS: ${{ matrix.no-extensions }}

.github/workflows/reusable-build-wheel.yml

@@ -9,6 +9,11 @@ on:
         description: Workflow artifact name containing dists
         required: true
         type: string
+      cython-tracing:
+        description: Whether to build Cython modules with line tracing
+        default: '0'
+        required: false
+        type: string
       os:
         description: VM OS to use, without version suffix
         default: ubuntu
@@ -64,6 +69,9 @@ jobs:
       uses: pypa/cibuildwheel@v2.16.2
       env:
         CIBW_ARCHS_MACOS: x86_64 arm64 universal2
+        CIBW_ENVIRONMENT: >-  # Cython line tracing for coverage collection
+          PIP_CONSTRAINT="requirements/cython.txt"
+          YARL_CYTHON_TRACING="${{ inputs.cython-tracing }}"
 
     - name: Upload built artifacts for testing and publishing
       uses: actions/upload-artifact@v3

requirements/test.txt

@@ -1,3 +1,4 @@
+-r cython.txt
 idna==3.4
 multidict==6.0.4
 pytest==7.4.3