Add unit tests, test infrastructure, and GitHub workflow

Co-authored-by: taylortom <1059083+taylortom@users.noreply.github.com>

Author: Copilot

.github/workflows/tests.yml

@@ -0,0 +1,13 @@
+name: Tests
+on: push
+jobs:
+  default:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - uses: actions/setup-node@master
+        with:
+          node-version: 'lts/*'
+          cache: 'npm'
+      - run: npm ci
+      - run: npm test

.gitignore

@@ -0,0 +1,3 @@
+node_modules/
+npm-debug.log
+.DS_Store

package-lock.json

@@ -19,6 +19,9 @@
     "semantic-release": "^25.0.2",
     "standard": "^17.1.0"
   },
+  "scripts": {
+    "test": "node tests/index.js"
+  },
   "release": {
     "plugins": [
       [