在测试JavaScript时，还有比setTimeout更好的方法来等待asnyc回调吗？ [英] Any better way than setTimeout to wait for asnyc callbacks when testing JavaScript?

问题描述

鉴于此代码：

showForm = function (url) {
        return $.get(url, function (html) {
             $('body').append();              
        });
 };

使用 sinon.js 时， jQuery.mockjax.js 和 expect.js ，我有以下通过测试：

When using sinon.js, jQuery.mockjax.js and expect.js, I have the following passing test:

it("showForm calls jQuery.append", function () {

    $.mockjax({
          url: '/fake'                    
    });

    var spy = sinon.spy($.fn, "append");             
    presenter.showForm('/fake');

    setTimeout(function () { 
        expect(spy.called).to.be.equal(true);
    }, 1000);
});

使用 setTimeout 函数等待来自异步 $。get 的回调闻起来很糟糕，如果我做了太多的话，它会减慢我的测试套件。

Using the setTimeout function to wait on the callback from the asynchronous $.get smells bad and it will slow down my test suite if I do too much of it.

然而，我觉得这个意图相当清楚，而且它似乎确实测试了我想要的东西。

However, I feel that the intent is reasonably clear and it does seem to test exactly what I want.

有没有更好的方法，请你解释一下是什么在你的答案中继续？

Is there a better way and can you please explain what's going on in your answer?

推荐答案

传递你的匿名函数将表单显示为参数并在回调后调用它附加。为了确保它被调用，你可以使它成为一个$ .ajax请求，它也包含错误回调。

Pass your anonymous function to show form as a parameter and have it called in the callback after the append. To ensure its called you could make it an $.ajax request that covers the error callback as well.

这样就可以在get请求完成且没有多余时间或过早调用时调用它。

This way it is called exactly when the get request finishes with no excess time or called too early.

showForm = function (url, callback) {
        return $.get(url, function (html) {
             $('body').append();   
             if(callback != undefined)
             callback();
        });
 };

it("showForm calls jQuery.append", function () {

    $.mockjax({
          url: '/fake'                    
    });

    var spy = sinon.spy($.fn, "append");

    presenter.showForm('/fake', function (){ 
        expect(spy.called).to.be.equal(true);
    });
});

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