promisify express app.listen with server as return value

promisify-express-listen.js

const app = require('express')();

async function start() {
  return new Promise((resolve, reject) => {
    // The `listen` method launches a web server.
    const server = app.listen();
    server.once('listening', resolve(server)).once('error', reject);
  });
}

async function run() {
  const server = await start();
}

run();