NextJS App Router cookie module mock with Bun/TypeScript

nextjs-mock.ts

import { mock } from "bun:test";
import { ReadonlyRequestCookies } from "next/dist/server/web/spec-extension/adapters/request-cookies";

export function mockNextjsReadonlyCookie() {
  mock.module("next/headers", () => {
    const cookieMap = new Map<string, { name: string; value: string }>();
    const cookies: ReadonlyRequestCookies = {
      get: (nameOrCookie: string | { name: string }) => {
        const name =
          typeof nameOrCookie === "string" ? nameOrCookie : nameOrCookie.name;
        const cookie = cookieMap.get(name);
        return cookie ? { name: cookie.name, value: cookie.value } : undefined;
      },
      has: (nameOrCookie: string | { name: string }) => {
        const name =
          typeof nameOrCookie === "string" ? nameOrCookie : nameOrCookie.name;
        return cookieMap.has(name);
      },
      set: () => {
        throw new Error(
          "You should not set cookies in readonly mode like Server Component or Data Access Layer",
        );
      },
      delete: () => {
        throw new Error(
          "You should not set cookies in readonly mode like Server Component or Data Access Layer",
        );
      },
      get size() {
        return cookieMap.size;
      },
      getAll: (...args: Array<string | { name: string }> | []) => {
        if (args.length === 0) {
          return Array.from(cookieMap.values());
        }
        const names = new Set(
          args.map((arg) => (typeof arg === "string" ? arg : arg.name)),
        );
        return Array.from(cookieMap.values()).filter((cookie) =>
          names.has(cookie.name),
        );
      },
      [Symbol.iterator]: () => cookieMap.entries(),
    };
    return {
      cookies: () => cookies,
      headers: () => {
        throw new Error("not implemented yet, mock this");
      },
      draftMode: () => {
        throw new Error("not implemented yet, mock this");
      },
    };
  });
}

export function mockNextjsMutableCookie() {
  mock.module("next/headers", () => {
    const cookieMap = new Map<string, { name: string; value: string }>();
    const cookies: ReadonlyRequestCookies = {
      get: (nameOrCookie: string | { name: string }) => {
        const name =
          typeof nameOrCookie === "string" ? nameOrCookie : nameOrCookie.name;
        const cookie = cookieMap.get(name);
        return cookie ? { name: cookie.name, value: cookie.value } : undefined;
      },
      has: (nameOrCookie: string | { name: string }) => {
        const name =
          typeof nameOrCookie === "string" ? nameOrCookie : nameOrCookie.name;
        return cookieMap.has(name);
      },
      set: (...args: [string, string] | [{ name: string; value: string }]) => {
        if (typeof args[0] === "string") {
          cookieMap.set(args[0], { name: args[0], value: args[1]! });
        } else if (typeof args[0] === "object") {
          const cookie = args[0];
          cookieMap.set(cookie.name, cookie);
        } else {
          throw new Error("Invalid cookie set or mock bug");
        }
        return cookies;
      },
      delete: (nameOrCookie: string | { name: string }) => {
        const name =
          typeof nameOrCookie === "string" ? nameOrCookie : nameOrCookie.name;
        if (cookieMap.has(name)) {
          cookieMap.set(name, { name, value: "" });
        }
        return cookies;
      },
      get size() {
        return cookieMap.size;
      },
      getAll: (...args: Array<string | { name: string }> | []) => {
        if (args.length === 0) {
          return Array.from(cookieMap.values());
        }
        const names = new Set(
          args.map((arg) => (typeof arg === "string" ? arg : arg.name)),
        );
        return Array.from(cookieMap.values()).filter((cookie) =>
          names.has(cookie.name),
        );
      },
      [Symbol.iterator]: () => cookieMap.entries(),
    };
    return {
      cookies: () => cookies,
      headers: () => {
        throw new Error("not implemented yet, mock this");
      },
      draftMode: () => {
        throw new Error("not implemented yet, mock this");
      },
    };
  });
}