Test with a GitHub action

.github/workflows/test.yml

@@ -0,0 +1,40 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+
+  test:
+
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [14.x]
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+        include:
+          - node-version: 15.x
+            os: ubuntu-latest
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Set up Node ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Use npm cache
+        uses: actions/cache@v2
+        with:
+          path: node_modules
+          key: ${{ runner.os }}-node${{ matrix.node-version }}-${{ hashFiles('**/package-lock.json') }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Test code
+        run: npm test