client.js

var io = require('socket.io/node_modules/socket.io-client');
var querystring = require('querystring');
var http = require('http');

var data = querystring.stringify({
  username: 'test',
  password: 'testtest'
});

var options = {
  hostname: 'localhost',
  port: 3000,
  path: '/api/auth/signin',
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Content-Length': Buffer.byteLength(data)
  }
};

var req = http.request(options, function(res) {
  console.log('STATUS: ' + res.statusCode);
  console.log('HEADERS: ' + JSON.stringify(res.headers));
  res.setEncoding('utf8');
  res.on('data', function (chunk) {
    console.log('BODY: ' + chunk);
  });

  var cookies;
  if (res.headers && res.headers['set-cookie'] && res.headers['set-cookie'].length > 0) {
    cookies = res.headers['set-cookie'].join(';');
  }

  var socket;

  if (cookies) {
    socket = io('http://localhost:3000', {
      extraHeaders: {
        'Cookie': cookies
      }
    });
  } else {
    socket = io('http://localhost:3000');
  }

  socket.on('connect', function () {
    console.log('connected');

    socket.on('chatMessage', function (data) {
      console.log(data);
      // done();
    });

    setTimeout(function () {
      socket.emit('chatMessage', 'testmessage');
    }, 100);
  });

  socket.on('disconnect', function () {
    console.log('disconnected');
  });

  socket.on('error', function (err) {
    console.log('error', err);
  });
});

req.on('error', function(e) {
  console.log('problem with request: ' + e.message);
});

req.write(data);
req.end();