Bug with a composition started with parallel

[igorgo]

Software version metasync: 0.3.26 Node: 8.11.3 NPM: 5.6.0

When the first item of an array of composed functions is a double brackets array (parallel executed), the next functions in the chain of a composition isn't called.

For example, the next code ...

const metasync = require('metasync')

function stubFunc (data, cb) {
  cb(null, data)
}

function fn1 (data, cb) {
  setTimeout(() => {
    console.log(`fn1 has been processed (data: ${data})`)
    cb(null, 1)
  }, 300)
}

function fn2 (data, cb) {
  setTimeout(() => {
    console.log(`fn2 has been processed (data: ${data})`)
    cb(null, 2)
  }, 300)
}

function fn3 (data, cb) {
  setTimeout(() => {
    console.log(`fn3 has been processed (data: ${data})`)
    cb(null, 3)
  }, 200)
}

function fn4 (data, cb) {
  setTimeout(() => {
    console.log(`fn4 has been processed (data: ${data})`)
    cb(null, 4)
  }, 300)
}

const fc = metasync([[[fn1, fn2]], fn3, fn4])

fc([0], (err, data) => {
  if (err) {
    console.log(err.message, 'data:', data)
  } else {
    console.log('Process finished. data:', data)
  }
})

...outputs

fn1 has been processed (data: 0)
fn2 has been processed (data: 0,1)
Process finished. data: [ 0, 1, 2 ]

Though, if I insert any function in the chain before the parallel group...

const fc = metasync([stubFunc, [[fn1, fn2]], fn3, fn4])

... then all function are called.

fn1 has been processed (data: 0)
fn2 has been processed (data: 0,1)
fn3 has been processed (data: 0,1,2)
fn4 has been processed (data: 0,1,2,3)
Process finished. data: [ 0, 1, 2, 3, 4 ]

[tshemsedinov]

Published in Version 0.3.29 @igorgo