问无法在Jest中用supertest (用于测试快速应用程序)测试delete

EN

const express = require('express')
const User = require('../models/user')
const auth=require('../middleware/auth')
const router= new express.Router()

router.delete('/users/me',auth, async(req, res)=>{
    try{
        req.user.remove()
        res.send(req.user)
    }catch(e){
        res.status(500).send()
    }
})

module.exports= router

const userRouter= require('./routers/user')
app.use(express.json())
app.use(userRouter)
module.exports= app 

const request = require('supertest')
const mongoose = require('mongoose')
const jwt = require('jsonwebtoken')
const app = require('../src/app')
const User = require('../src/models/user') 

const userOneId = new mongoose.Types.ObjectId()
const userOne = {
    _id: userOneId,
    name: 'Mike',
    email: 'mike@example.com',
    password: '56what!!',
    tokens: [{
        token: jwt.sign({ _id: userOneId }, process.env.JWT_SECRET)
    }]
}

beforeEach(async()=>{
    await User.deleteMany()
    await new User(userOne).save()
})

test('Should login existing user', async () => {
    const response = await request(app).post('/users/login').send({
        email: userOne.email,
        password: userOne.password
    }).expect(200)
    const user = await User.findById(userOneId)
    expect(response.body.token).toBe(user.tokens[1].token)
})

test('Should not login nonexistent user', async () => {
    await request(app).post('/users/login').send({
        email: userOne.email,
        password: 'thisisnotmypass'
    }).expect(400)
})

test('Should not delete account for unauthenticate user', async () => {
    await request(app)
        .del('/users/me')
        .send()
        .expect(401)
})

test('Should delete account for user', async () => {
    await request(app)
        .del('/users/me')
        .set('Authorization', `Bearer ${userOne.tokens[0].token}`)
        .send()
        .expect(200)
    //the lines of code below are not working
    const user = await User.findById(userOneId)
    expect(user).toBeNull()
})

Tests:       1 failed, 8 passed, 9 total
  ● Should delete account for user

    expect(received).toBeNull()

    Received: {"__v": 0, "_id": "630477018ef98753a4efebbe", "age": 0, "createdAt": 2022-08-23T06:43:14.383Z, "email": "mike@example.com", "id": "630477018ef98753a4efebbe", "name": "Mike", "updatedAt": 2022-08-23T06:43:14.383Z}

      89 |     //the lines of code below are not working
      90 |     const user = await User.findById(userOneId)
    > 91 |     expect(user).toBeNull()
         |                  ^
      92 | })
      93 |
      94 |

      at Object.toBeNull (tests/user.test.js:91:18)

"scripts": {
    "start": "node src/index.js",
    "dev": "env-cmd ./config/dev.env nodemon src/index.js",
    "test": "env-cmd ./config/test.env jest --watch"
  },
  "jest": {
    "testEnvironment": "node"
  },

PORT=3000
MONGODB_URL=mongodb://127.0.0.1:27017/task-manager-api-test