Add coverage test

.github/workflows/main.yml

@@ -39,14 +39,23 @@ jobs:
           pandoc-version: "2.9.2"
       - name: Install tox
         run: python -m pip install -U pip tox
+      - name: Install invoke
+        run: python -m pip install invoke
       - name: Info
         run: |
           echo "=====  PYTHON  ====="
           python --version
           echo "=====  PANDOC  ====="
           pandoc --version | head -2
-      - name: Run tests
-        run: tox -e py${{ matrix.python }}
+      - name: Run tests with coverage
+        run: invoke coverage
+
+      - name: Upload coverage data
+        uses: "actions/upload-artifact@v4"
+        with:
+          name: coverage-data
+          path: ".coverage.*"
+          if-no-files-found: error
 
   lint:
     name: Lint
@@ -66,6 +75,32 @@ jobs:
       - name: Run pre-commit checks on all files
         uses: pre-commit/action@v3.0.1
 
+  coverage:
+    runs-on: "ubuntu-latest"
+    needs: test
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python ${{ matrix.python }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python }}
+          cache: "pip"
+          cache-dependency-path: "**/requirements/*"
+
+      - name: "Install Coverage.py"
+        run: "python -m pip install --upgrade coverage[toml]"
+
+      - name: "Download coverage data"
+        uses: actions/download-artifact@v4
+        with:
+          name: coverage-data
+
+      - name: "Combine & check coverage"
+        run: |
+          set -xe
+          python -m coverage combine
+          python -m coverage report --fail-under=74
+
   build:
     name: Test build
     runs-on: ubuntu-latest