streams.thenable.js

(function(){
  const EE = require('events')
  const Stream = require('stream')
  const promise = Symbol('StreamPromise')

  Stream.prototype.constructor = function () {
    EE.call(this)
    this[promise] = new Promise((resolve, reject) => {
      this.on('error', reject)
      this.on('end', resolve)
      this.on('finish', resolve)
    })
  }

  Stream.prototype.then = function (yay, nay) {
    return this[promise].then(yay, nay)
  }
})()