test.js

import path from 'path'
import { fileURLToPath } from 'url'
import { execa } from 'execa'
import pDefer from 'p-defer'
import { toString as uint8ArrayToString } from 'uint8arrays/to-string'

const __dirname = path.dirname(fileURLToPath(import.meta.url))

function startProcess (name) {
  return execa('node', [path.join(__dirname, name)], {
    cwd: path.resolve(__dirname),
    all: true
  })
}

const message = 'test message'
let listenerOutput = ''
let dialerOutput = ''

let isListening = false
let messageSent = false
const listenerReady = pDefer()
const dialerReady = pDefer()
const messageReceived = pDefer()

// Step 1 process
process.stdout.write('node listener.js\n')
const listenerProc = startProcess('./src/listener.js')
listenerProc.all.on('data', async (data) => {
  process.stdout.write(data)

  listenerOutput += uint8ArrayToString(data)

  if (!isListening && listenerOutput.includes('Listener ready, listening on')) {
    listenerReady.resolve()
    isListening = true
  } else if (isListening && listenerOutput.includes(message)) {
    messageReceived.resolve()
  }
})

await listenerReady.promise
process.stdout.write('==================================================================\n')

// Step 2 process
process.stdout.write('node dialer.js\n')
const dialerProc = startProcess('./src/dialer.js')
dialerProc.all.on('data', async (data) => {
  process.stdout.write(data)
  dialerOutput += uint8ArrayToString(data)

  if (!messageSent && dialerOutput.includes('Type a message and see what happens')) {
    dialerReady.resolve()
    dialerProc.stdin.write(message)
    dialerProc.stdin.write('\n')
    messageSent = true
  }
})

await dialerReady.promise
process.stdout.write('==================================================================\n')
await messageReceived.promise
process.stdout.write('chat message received\n')

listenerProc.kill()
dialerProc.kill()
await Promise.all([
  listenerProc,
  dialerProc
]).catch((err) => {
  if (err.signal !== 'SIGTERM') {
    throw err
  }
})