Add tests for declaform.

package.json

@@ -4,11 +4,15 @@
   "description": "A collection of useful web components and functionality.",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "npx jest"
   },
   "author": "Austin Smith",
   "license": "ISC",
   "devDependencies": {
+    "@types/jest": "^30.0.0",
+    "jest": "^30.2.0",
+    "jest-environment-jsdom": "^30.2.0",
+    "ts-jest": "^29.4.5",
     "typescript": "^5.9.2"
   }
 }