gistfile1.js

var vows = require('vows'),
    assert = require('assert');

function wait(callback) {
  
  setTimeout(function() {
    callback('hello', 'world');
  }, 2000)
  
}

vows.describe('Playing with asynched functions').addBatch({
  'wait()': {
    topic: function() {
      wait(this.callback.bind(this, null));
    },

    'should return "hello" and "world"': function(_, arg1, arg2) {
      assert.strictEqual(arg1, 'hello');
      assert.strictEqual(arg2, 'world'); // why is arg2 undefined?
    }
  }
}).export(module);

vows.out

♢ Playing with asynched functions

  wait()
    ✓ should return "hello" and "world"
 
✓ OK » 1 honored (2.004s)