Mirror the approach used when running the action in the test workflow

The test workflow will be most effective if it emulates the environment the action will run in.

Author: per1234

.github/workflows/test-python.yml

@@ -4,15 +4,16 @@ on:
   pull_request:
     paths:
       - '.github/workflows/test-python.yml'
+      - 'action-setup.sh'
       - 'compilesketches/**'
 
   push:
     paths:
       - '.github/workflows/test-python.yml'
+      - 'action-setup.sh'
       - 'compilesketches/**'
 
-  # The actions/setup-python action will periodically break the workflow by dropping the Python version we have pinned
-  # Better to catch that before it causes confusion for a contributor
+  # Catch issues resulting from new patch releases of Python in the APT repository
   schedule:
     # run every Tuesday at 3 AM UTC
     - cron: "0 3 * * 2"
@@ -32,29 +33,52 @@ jobs:
     env:
       PYTHON_PROJECT_PATH: ${GITHUB_WORKSPACE}/compilesketches
       PYTHON_PROJECT_TESTS_PATH: ${GITHUB_WORKSPACE}/compilesketches/tests
+      COVERAGE_DATA_FILENAME: coverage.xml
 
     steps:
       - name: Checkout
         uses: actions/checkout@v2
 
-      - name: Set up Python
-        uses: actions/setup-python@v1
-        with:
-          python-version: '3.8.6'
+      - name: Run the set up script
+        id: setup
+        run: |
+          "${{ github.workspace }}/action-setup.sh"
 
-      - name: Install dependencies
+      - name: Install test dependencies
         run: |
-          python -m pip install --upgrade pip
-          pip install --requirement "${{ env.PYTHON_PROJECT_TESTS_PATH }}/requirements.txt"
+          source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
+          "${{ steps.setup.outputs.python-command }}" \
+            -m \
+              pip install \
+                --requirement "${{ env.PYTHON_PROJECT_TESTS_PATH }}/requirements.txt"
 
-      - name: Run Python unit tests and report code coverage
+      - name: Run Python unit tests and record code coverage data
         run: |
+          source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
           export PYTHONPATH="${{ env.PYTHON_PROJECT_PATH }}"
-          coverage run --source="${{ env.PYTHON_PROJECT_PATH }}" --module pytest "${{ env.PYTHON_PROJECT_TESTS_PATH }}"
-          # Display code coverage report in workflow run log
-          coverage report
+          "${{ steps.setup.outputs.python-command }}" \
+            -m \
+              coverage run \
+                --rcfile="${{ env.PYTHON_PROJECT_TESTS_PATH }}/.coveragerc" \
+                --source="${{ env.PYTHON_PROJECT_PATH }}" \
+                --module \
+                  pytest "${{ env.PYTHON_PROJECT_TESTS_PATH }}"
+          # Generate coverage data file for consumption by `codecov/codecov-action`.
+          # Otherwise that action generates the file using the system Python environment, which doesn't work.
+          "${{ steps.setup.outputs.python-command }}" \
+            -m \
+              coverage xml \
+                -o "${{ github.workspace }}/${{ env.COVERAGE_DATA_FILENAME }}"
+
+      - name: Display code coverage report
+        run: |
+          source "${{ steps.setup.outputs.python-venv-activate-script-path }}"
+          "${{ steps.setup.outputs.python-command }}" \
+            -m \
+              coverage report
 
       - name: Upload coverage report to Codecov
         uses: codecov/codecov-action@v1
         with:
+          file: ${{ env.COVERAGE_DATA_FILENAME }}
           fail_ci_if_error: true

compilesketches/tests/.coveragerc

@@ -0,0 +1,3 @@
+[run]
+omit =
+    */.venv/*