How to use Jest and Supertest with Fastify?

I'm trying to use Jest and Supertest with Fastify. I have this test file.

// @ts-nocheck
import { FastifyInstance } from 'fastify'
import request from 'supertest'
import app from '../app'

let server: FastifyInstance

beforeAll(async () => {
    server = app.server;
})

afterAll(() => {
    server.close()
})

test('Should get a 200 OK', async () => {
    const response = await request(server).get('/')
    expect(response.status).toBe(200)
})

My app.ts:

import fastify from 'fastify'
import dotenv from 'dotenv'

dotenv.config()

import appRoute from './routes/app'

const app = fastify({ logger: true })

app.register(appRoute)

export default app

But I always get a timeout... Could anyone provide an example of how to use Jest and Supertest with Fastify?

There is an example in the official document at the bottom about writing testings with supertest. See testing

Make sure you call the done callback of the fasity.register() API.

index.js:

const Fastify = require('fastify');

const app = Fastify({ logger: true });

app.register((instance, opts, done) => {
  instance.get('/', (request, reply) => {
    reply.send({ hello: 'world' });
  });
  done();
});

module.exports = app;

index.test.js:

const supertest = require('supertest');
const app = require('./');

afterAll(() => app.close());

test('GET `/` route', async () => {
  await app.ready();

  const response = await supertest(app.server)
    .get('/')
    .expect(200)
    .expect('Content-Type', 'application/json; charset=utf-8');

  expect(response.body).toEqual({ hello: 'world' });
});

Test result:

❯ npm run test
$ jest
{"level":30,"time":1673234788774,"pid":70,"hostname":"noderfv2fs-ky0o","reqId":"req-1","req":{"method":"GET","url":"/","hostname":"127.0.0.1:62766"},"msg":"incoming request"}
{"level":30,"time":1673234788777,"pid":70,"hostname":"noderfv2fs-ky0o","reqId":"req-1","res":{"statusCode":200},"responseTime":2.5850000000000364,"msg":"request completed"}
 PASS  ./index.test.js
  ✓ GET `/` route (489 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        2.269 s, estimated 3 s
Ran all test suites.

stackblitz(Open using Chrome, there is a bug when run npm run test using Microsoft Edge)