javascript - 无法使用 Sinon 模拟 http.ServerResponse

Question

我的方法接受 http.ServerResponse 并调用它的一些方法。正在查看Sinon's docs看来这应该是微不足道的。但是，如果我没有设置期望，我要么得到 TypeError: response.writeHead is not a function ，要么得到 TypeError: Attempted towrapp undefined property writeHead as function 如果我请设置一个。

var http = require('http'),
    sinon = require('sinon'),
    ServerResponse = http.ServerResponse;


function SendWelcomeResponse(response) {
    var body = 'Hello World!';

    response.writeHead(200, {'Content-Type': 'text/plain', 'Content-Length': body.length});
    response.write(body);
    response.end();
}

describe('Using Sinon I should be able to mock the ServerResponse', function () {
    it.only('should mock correctly', function () {
        var mockServerResponse = sinon.mock(ServerResponse);
        mockServerResponse.expects('writeHead').once();
        SendWelcomeResponse(mockServerResponse);
    });
});

手动滚动对象进行模拟

我刚刚尝试了下面的两个建议，这些建议给出了TypeError:response.writeHead不是一个函数。

var sinon = require('sinon'),
    stubServerResponse = {
        writeHead: function(statusCode, headers) {},
        write: function(body){},
        end: function() {}
    };


function SendWelcomeResponse(response) {
    var body = 'Hello World!';

    response.writeHead(200, {'Content-Type': 'text/plain', 'Content-Length': body.length});
    response.write(body);
    response.end();
}

describe('Using Sinon I should be able to mock the ServerResponse', function () {
    it.only('should mock correctly', function () {
        var mockServerResponse = sinon.mock(stubServerResponse);
        mockServerResponse.expects('writeHead').once();
        SendWelcomeResponse(mockServerResponse);
    });
});

工作!

神奇之处在于下面建议的解决方案，并使用模拟对象的 .object 属性而不是对象本身。下面给出绿色测试!

var sinon = require('sinon'),
    stubServerResponse = {
        writeHead: function(statusCode, headers) {},
        write: function(body){},
        end: function() {}
    };


function SendWelcomeResponse(response) {
    var body = 'Hello World!';

    response.writeHead(200, {'Content-Type': 'text/plain', 'Content-Length': body.length});
    response.write(body);
    response.end();
}

describe('Using Sinon I should be able to mock the ServerResponse', function () {
    it.only('should mock correctly', function () {
        var mockServerResponse = sinon.mock(stubServerResponse);
        mockServerResponse.expects('writeHead').once();
        SendWelcomeResponse(mockServerResponse.object);
    });
});

Answer 1

它看起来像 sinon.mock 只 stub 你传递的对象的 hasOwnProperty 方法；

https://github.com/sinonjs/sinon/blob/master/lib/sinon/extend.js#L63

我认为ServerResponse.writeHead是在原型(prototype)上实现的。这样它的方法就不会被直接模拟。

一种选择是创建一个实现 writeHead 、 writeHead 和 end 的模拟对象，监视这些方法并对其进行断言。创建模拟对象时这将是一个更加手动的过程......