Add test script and Actions workflow

.github/workflows/test.yml

@@ -0,0 +1,25 @@
+name: Run Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Set Node.JS
+      uses: actions/setup-node@v3
+      with:
+        node-version: 16.x
+
+    - name: Install dependencies
+      run: npm ci
+    
+    - name: Run tests
+      run: npm test

package.json

@@ -4,7 +4,8 @@
   "description": "",
   "main": "src/index.js",
   "scripts": {
-    "prepare": "ncc build src/index.js -o dist --source-map --license licenses.txt"
+    "prepare": "ncc build src/index.js -o dist --source-map --license licenses.txt",
+    "test": "jest"
   },
   "repository": {
     "type": "git",