faux.js

var assert = require('assert');
var stream = require('stream');
var util = require('util');
var net = require('net');
var PORT = 12345;

function Faux() {
  stream.Stream.call(this);

  this.write = function(buf) {
    this.emit('data', buf);
  };

  this.end = function() {
  };
}
util.inherits(Faux, stream.Stream);

(function() {
  var ok = false;

  process.on('exit', function() {
    assert(ok);
  });

  var server = net.createServer(function(conn) {
    conn.pipe(new Faux).pipe(conn);
    server.close();
  });

  server.listen(PORT, function() {
    var conn = net.createConnection(PORT);
    conn.setEncoding('utf-8');
    conn.write('test');
    conn.on('data', function(s) {
      assert.equal(s, 'test');
      ok = true;
      conn.destroy();
    });
  });
})();