Using coffeescript vowsjs for Async tests

async.coffee

vows   = require 'vows'
assert = require 'assert'

cb = (callback) ->
  setTimeout ->
      callback(null, 'callback')
    , 2000

andWaitForCallback = undefined

vows
  .describe('Callback Example')
  .addBatch
    'base:':
      topic: ->
        cb @callback
        andWaitForCallback
      "should be callback": (err, result) ->
        assert.equal result, 'callback'
  .export module