Node.js: splitting stream content for n-parts

I'm trying to understand node streams and their life-cycle. So, I want to split a content of a stream for n-parts. The code below is just to explain my intentions and to show that I already try something by myself. I omitted some details

I have a stream which just generates some data(just a sequence of data):

class Stream extends Readable {
  constructor() {
    super({objectMode: true, highWaterMark: 1})
    this.counter = 0
  }

  _read(size) {
    if(this.counter === 30) {
      this.push(null)
    } else {
      this.push(this.counter)
    }
    this.counter += 1
  }
}

const stream = new Stream()
stream.pause();

a function which tries to take n next chunks:

function take(stream, count) {
  const result = []
  return new Promise(function(resolve) {
    stream.once('readable', function() {
      var chunk;
      do {
        chunk = stream.read()
        if (_.isNull(chunk) || result.length > count) {
          stream.pause()
          break
        }
        result.push(chunk)
      } while(true)
      resolve(result)
    })
  })
}

and want to use it like this:

take(stream, 3)
  .then(res => {
    assert.deepEqual(res, [1, 2, 3])
    return take(stream, 3)
  })
  .then(res => {
    assert.deepEqual(res, [4, 5, 6])
  })

What is the idiomatic way to do that?

via kharandziuk