Add GH actions workflow

.github/workflows/test.yml

@@ -0,0 +1,36 @@
+name: Tests
+on: [push, pull_request]
+env:
+  CI: true
+
+jobs:
+  run:
+    name: Node ${{ matrix.node }} on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        node: [12, 14, 15]
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v1
+
+      - name: Set Node.js version
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node }}
+
+      - run: node --version
+      - run: npm --version
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
+        shell: bash
+        env:
+          SHELL: "/bin/bash"