silly little thing.

MockAjax.js

function MockAjax() {
	var self = this;
	var responses = {
		'http://api.example.com/cart/add.json?a=5&b=3': {
			"data": 8
		}
	};

	function request(url, success, failure) {
		window.setTimeout(function () {
			if (responses[url] === undefined) {
				failure();
				return;
			}
			success(responses[url]);
		}, Math.random() * 1000);
	}

	self.mock = function(url, response) {
		responses[url] = response;
	};
	self.get = function(url, success, failure) {
		request(url, success, failure);
	};
	
	self.post = function(url, success, failure) {
		request(url, success, failure);
	};

	return self;
}