Node.js testing - app.address is not a function

After managing to write a test for a get request on my app, I am trying a post request. After some research online I managed to write the following test:

const request = require('supertest')
const app = require('../main/http')

describe('Testing the /new-comp post', () => {
  it('should post a new comp', async () => {
    const res = await request(app)
      .post('/new-comp')
      .send({
        id: 'Some ID',
        compName: 'Another name',
        place: 'Poznan',
        time: '10 am',
        subscriptions: [],
        date: '1596135253446',
        cost: {
          currency: 'EUR',
          amount: 50,
        },
      })
    expect(res.StatusCode).toEqual(201)
    expect(res.body).toHaveProperty('post')
  })
})

The path I am testing is in the following bunch of code:

import { eventApplication } from './compositionRoot'
import { Schema } from 'mongoose'
export const mongoose = require('mongoose')

const express = require('express')
export const app = express()
const bodyParser = require('body-parser')
//const urlEncodedParser = bodyParser.urlencoded({ extended: false })

mongoose.connect('mongodb://localhost:27017/CompetitionEvent')
export const db = mongoose.connection
db.on('error', console.error.bind(console, 'An error has occured: '))
db.once('open', function () {
  console.log('Connected to Mongodb')
})

const CompetitionSchema = new Schema({
  id: String,
  compName: String,
  place: String,
  time: String,
  subscriptions: [],
  date: Date,
  cost: {
    currency: String,
    amount: Number,
  },
})

const CompetitionModel = mongoose.model('CompetitionModel', CompetitionSchema)

app.use(bodyParser.json())
app.get('/events', (_req: any, res: any) => {
  res.send(eventApplication.getAll())
})

app.post('/event', async (req: any, res: any) => {
  await eventApplication.createAnEvent(req.body)
  res.json({
    success: true,
  })
})

app.post('/new-comp', async (req: any, res: any) => {
  const newComp = CompetitionModel(req.body)
  const data = await newComp.save()
  res.json(data)
})

// NEED TO ADD COMPETITION NAME FIELD!!!

app.listen(5000)

I keep having an issue with "TypeError app.address is not a function"
Also I noticed an async issue in the code that I am not (yet) able to identify, being a beginner in node. Anyone has an idea?
Cheers