Add chai for assertion

Author: khiga8

package.json

@@ -51,6 +51,7 @@
   ],
   "devDependencies": {
     "@github/prettier-config": "0.0.4",
+    "chai": "^4.3.6",
     "eslint": "^8.0.1",
     "eslint-plugin-eslint-plugin": "^5.0.0",
     "mocha": "^10.0.0"