Add GitHub workflow.

.github/workflows/node.js.yml

@@ -0,0 +1,37 @@
+name: CI
+
+on:
+  push:
+    branches: [ source ]
+  pull_request:
+    branches: [ source ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [14.x]
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    - name: Setup Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Install dependencies
+      run: npm i
+
+    - name: Run linting
+      run: npm run lint
+
+    - name: Run tests
+      run: npm run coverage
+
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v1