我想用mocha和should来给自己的服务器加上单元测试，但是在测试restful方法的时候遇到了问题始终抱一个错误

http #Rest method should return json by rest method:
Uncaught Error: connect ECONNREFUSED
at exports._errnoException (util.js:746:11)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1010:19)

describe('http',function(){
    describe('#Rest method',function(){
        it("should return json by rest method",function(err,res,req){
            request
                .get(url+'/user:wen')
                .on('response',function(res){
                    if(err)throw err;
                    res.should.status(200).json;
                    res.body.should.not.empty;
                    done();
                })
        })
    })
})