如何在 Mocha 测试中模拟时间的流逝，以便调用 setTimeout 回调? [英] How can I simulate the passing of time in Mocha tests so that setTimeout callbacks are called?

问题描述

为了执行周期性任务，我需要测试依赖于 setTimeout 的 JavaScript 代码.如何从我的 Mocha 测试中模拟时间的流逝，以便调用 setTimeout 回调?

I need to test JavaScript code that relies on setTimeout in order to perform periodic tasks. How can I from my Mocha tests simulate the passing of time so that setTimeout callbacks gets called?

我基本上要求类似于 Jasmine 的模拟时钟 的功能，它允许您将 JavaScript 时间提前若干滴答声.

I am basically asking for functionality similar to Jasmine's Mock Clock, which allows you to advance JavaScript time by a number of ticks.

推荐答案

我发现 Sinon.JS 支持通过 sinon.useFakeTimers 操作 JavaScript 时钟，如其 假计时器 文档.这是完美的，因为我已经将 Sinon 用于模拟目的，而且我想 Mocha 本身不支持这一点是有道理的，因为它更多地属于模拟库的领域.

I found out that Sinon.JS has support for manipulating the JavaScript clock, via sinon.useFakeTimers, as described in its Fake Timers documentation. This is perfect since I already use Sinon for mocking purposes, and I guess it makes sense that Mocha itself doesn't support this as it's more in the domain of a mocking library.

这是一个使用 Mocha/Chai/Sinon 的示例:

Here's an example employing Mocha/Chai/Sinon:

var clock;
beforeEach(function () {
     clock = sinon.useFakeTimers();
 });

afterEach(function () {
    clock.restore();
});

it("should time out after 500 ms", function() {
    var timedOut = false;
    setTimeout(function () {
        timedOut = true;
    }, 500);

    timedOut.should.be.false;
    clock.tick(510);
    timedOut.should.be.true;
});

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