Add GitHub Actions workflow for running tests

Author: garrytrinder

.github/workflows/pr.yml

@@ -0,0 +1,25 @@
+name: Run tests
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [macos-latest, ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Install Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18.x
+      - run: npm install
+      - run: xvfb-run -a npm test
+        if: runner.os == 'Linux'
+      - run: npm test
+        if: runner.os != 'Linux'