ci: add GitHub Action for testing code on push and pull requests

.github/workflows/test.yml

@@ -0,0 +1,22 @@
+name: Test
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Run tests
+    runs-on: ubuntu-18.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Node.js setup
+        uses: actions/setup-node@v1
+        with:
+          node-version: 12
+      - name: Install dependencies
+        run: npm ci
+      - name: Lint
+        run: npm run lint
+      - name: Test
+        run: npm test