Testing is not working as expected

[LuisMalhadas]

I am probably doing it wrong, but I need some help, because it's just the test that is not working...
The following test:

import { expect, test, beforeAll, afterAll, afterEach, beforeEach} from "bun:test";
import server from "bunrest";

const app = server();
let service;

beforeAll(async () => {
    service = app.listen(3000, () => {
        console.log('App is listening on port 3000');
    });
});

afterAll(async () => {
    service.stop();
});

test("should respond OK for ping", async () => {
    try {
        const res = await fetch('http://localhost:3000/ping');
        expect(res.status).toBe(200);
        expect(await res.text()).toBe('OK')
    } catch (e) {
        throw e;
    } 
});

The index.ts:

import server from "bunrest";
import cors from "cors";
import router from "./src/core/Router.js";

const app = server();
const port = 3000;

// add router
//const router = app.router();
app.use('/', router);

app.use(cors());

app.listen(port, () => {
  console.log(`App is listening on port`, port);
});

For the route.ts:

import server from "bunrest";
const app = server();

// add router
const router = app.router();

router.get('/ping', (req, res) => {
    //console.log("[/ping] RECEIVED: ", req);
    res.status(200).send('OK');
});

These are the reduced versions.
Running bun test outputs:

Router.test.ts:
App is listening on port 3000
133 |         const res = that.responseProxy();
134 |         const tree: TrieTree<string, Handler> =
135 |           that.requestMap[req.method.toLowerCase()];
136 | 
137 |         if (!tree) {
138 |           throw new Error(`There is no path matches ${req.method}`);
                    ^
error: There is no path matches GET
      at /Users/luismal/Projects/Sia_AA/node_modules/bunrest/src/server/server.ts:138:16
GET - http://localhost:3000/ping failed
Database connection to  mongodb://localhost:27017/SIA  established.
20 |     console.log(result);
21 |     expect(result).toBe("OK");
22 |     */
23 |     try {
24 |         const res = await fetch('http://localhost:3000/ping');
25 |         expect(res.status).toBe(200);
            ^
error: expect(received).toBe(expected)

Expected: 200
Received: 500

      at /Users/luismal/Projects/Sia_AA/tests/Router.test.ts:25:8
✗ should respond OK for ping

[lau1944]

Try to use cors from npm instead of @types/cors from bun itself.

[LuisMalhadas]

I was missing app.use('/', router); on my example test.