stream-data to buffer and string

stream.util.js

const {Readable, PassThrough} = require('stream')
const {createReadStream} = require('fs')

const {ok, equal} = require('assert')

describe('toString', function(){
  it('converts a fs-stream to buffer', done => {
    let stream = createReadStream('/dev/null')

    toString(stream, function(string){
      equal(string, String())
      ok(~ done())
    })
  })

  it('converts a readable-stream to buffer', done => {
    let stream = new Readable()
    stream._read = Function.prototype // stubbed
    toBuffer(stream, function(buffer){
      equal(buffer, 'foo')
      ok(~ done())
    })
    stream.push('foo')
    stream.push(null)
  })

  it('converts a passthrough-stream to buffer', done => {
    let stream = new PassThrough()
    toBuffer(stream, function(buffer){
      equal(buffer, 'foo')
      ok(~ done())
    })
    stream.write('foo')
    stream.end()
  })
})

function toBuffer(stream, fn, chunks = []){
  stream.on('data', chunk => chunks.push(chunk))
  stream.on('end', data => fn(Buffer.concat(chunks)))
}

function toString(stream, fn){
  return toBuffer(stream, (buffer) => fn(buffer.toString()))
}