close.js

'use strict'

let express = require('express')
let axios = require('axios')

let server

function once (cb) {
  let app = express()
  app.get('/foo', (req, res, next) => {
    res.send('ok')
    cb()
  })
  return app
}

let app = once(function () {
  server.close(function () {
    console.log('Does this get called?')
  })
})

server = app.listen(28090, function () {
  axios.get('http://localhost:28090/foo').then(function (response) {
    console.log('GOT', response.data)
  })
})