How to delay responses on connect middleware, eg, to test timeouts, on a yeoman's generated gruntfile.

Gruntfile.js

'use strict';

var lrSnippet = require('grunt-contrib-livereload/lib/utils').livereloadSnippet;

var mountFolder = function (connect, dir) {
  return connect.static(require('path').resolve(dir));
};

// ...

var connectDelayer = function (connect, test, delay) {
  var DelayedStream = require('delayed-stream');

  return function (req, res, next) {
    if (test(req)) {
      var delayed = DelayedStream.create(req);

      setTimeout(function() {
        delayed.resume();
      }, delay);
    }
    return next();
  };
};

// ...

    connect: {
      livereload: {
        options: {
          debug: true,
          port: 9000,
          // Change this to '0.0.0.0' to access the server from outside.
          hostname: 'localhost',
          middleware: function (connect) {
            return [
              queryParser(connect),
              connectDelayer(connect, function (req) {
                return req._parsedUrl.pathname === '/lookup' && req.query.entity === 'value'; // or some other condition
              }, 5000), // delay
              proxySnippet,
              lrSnippet,
              mountFolder(connect, '.tmp'),
              mountFolder(connect, yeomanConfig.app)
            ];
          }
        }
      },

// ...

I wrote a grunt plugin to automate the process a little bit grunt-connect-delay.