add coverage workflow

.github/workflows/coverage.yml

@@ -0,0 +1,26 @@
+name: Tests + Coverage
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [16.x, 18.x]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Set up Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run the tests
+        run: npm run test -- --coverage