Add GitHub Action test

Copied from standard/standard, with addition of 16.x

.github/workflows/test.yml

@@ -0,0 +1,39 @@
+name: Test
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x, 16.x]
+      fail-fast: false
+
+    steps:
+      - name: Checkout project
+        uses: actions/checkout@v2
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Cache Node dependencies
+        uses: actions/[email protected]
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-node-${{ hashFiles('**/package.json') }}
+          restore-keys: |
+            ${{ runner.os }}-node-
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test