node/test/parallel/test-domain-multi.js

// Tests of multiple domains happening at once.

var common = require('../common');
var assert = require('assert');
var domain = require('domain');
var events = require('events');

var caughtA = false;
var caughtB = false;
var caughtC = false;


var a = domain.create();
a.enter(); // this will be our "root" domain
a.on('error', function(er) {
  caughtA = true;
  console.log('This should not happen');
  throw er;
});


var http = require('http');
var server = http.createServer(function (req, res) {
  // child domain of a.
  var b = domain.create();
  a.add(b);

  // treat these EE objects as if they are a part of the b domain
  // so, an 'error' event on them propagates to the domain, rather
  // than being thrown.
  b.add(req);
  b.add(res);

  b.on('error', function (er) {
    caughtB = true;
    console.error('Error encountered', er)
    if (res) {
      res.writeHead(500);
      res.end('An error occurred');
    }
    // res.writeHead(500), res.destroy, etc.
    server.close();
  });

  // XXX this bind should not be necessary.
  // the write cb behavior in http/net should use an
  // event so that it picks up the domain handling.
  res.write('HELLO\n', b.bind(function() {
    throw new Error('this kills domain B, not A');
  }));

}).listen(common.PORT);

var c = domain.create();
var req = http.get({ host: 'localhost', port: common.PORT })

// add the request to the C domain
c.add(req);

req.on('response', function(res) {
  console.error('got response');
  // add the response object to the C domain
  c.add(res);
  res.pipe(process.stdout);
});

c.on('error', function(er) {
  caughtC = true;
  console.error('Error on c', er.message);
});

process.on('exit', function() {
  assert.equal(caughtA, false);
  assert.equal(caughtB, true)
  assert.equal(caughtC, true)
  console.log('ok - Errors went where they were supposed to go');
});