Fix Anchor and add unit tests for it

Author: hasparus

package.json

@@ -93,8 +93,12 @@
     "@next/eslint-plugin-next": "^15.3.3",
     "@playwright/test": "^1.54.2",
     "@svgr/webpack": "^8.1.0",
+    "@testing-library/dom": "^10.4.1",
+    "@testing-library/jest-dom": "^6.8.0",
+    "@testing-library/react": "^16.3.0",
     "@types/codemirror": "5.60.16",
     "@types/hast": "3.0.4",
+    "@types/jsdom": "^21.1.7",
     "@types/node": "^22.10.5",
     "@types/react": "^18.3.23",
     "@types/rss": "0.0.32",
@@ -107,6 +111,7 @@
     "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-react-hooks": "^5.2.0",
     "eslint-plugin-tailwindcss": "3.18.2",
+    "jsdom": "^26.1.0",
     "prettier": "3.5.3",
     "prettier-plugin-pkg": "^0.20.0",
     "prettier-plugin-tailwindcss": "^0.6.12",