node/test/parallel/test-debug-port-cluster.js

'use strict';
var common = require('../common');
var assert = require('assert');
var spawn = require('child_process').spawn;

const PORT_MIN = common.PORT + 1337;
const PORT_MAX = PORT_MIN + 2;

var args = [
  '--debug=' + PORT_MIN,
  common.fixturesDir + '/clustered-server/app.js'
];

const child = spawn(process.execPath, args);
child.stderr.setEncoding('utf8');

let stderr = '';
child.stderr.on('data', (data) => {
  stderr += data;
  if (child.killed !== true && stderr.includes('all workers are running'))
    child.kill();
});

process.on('exit', () => {
  for (let port = PORT_MIN; port <= PORT_MAX; port += 1)
    assert(stderr.includes(`Debugger listening on port ${port}`));
});