const collectEvents = (eventEmmiter, eventName, count=1) => {
  return new Promise((resolve) => {
    const result = []
    const listener = (msg) => {
      result.push(msg)
      if(result.length === count) {
        resolve(result)
        eventEmmiter.removeListener(eventName, listener)
      }
    }
    eventEmmiter.on(eventName, listener)
  })
}

Promise.all([
  collectEvents(client1, 'message'),
  collectEvents(client2, 'message')
]).then(