Set up GitHub Actions CI

.github/workflows/test.yml

@@ -0,0 +1,33 @@
+name: Lint and test code (cross-platform)
+
+on: [push]
+
+jobs:
+
+  run:
+    name: Run
+
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+        node-version: [8.x, 10.x, 12.x]
+
+    steps:
+
+    - uses: actions/checkout@v1
+
+    - name: Use Node.js ${{ matrix.node-version }} on ${{ matrix.os }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Install
+      run: npm install
+
+    - name: Lint
+      run: npm run lint
+
+    - name: Test
+      run: npm test