当您收到超时错误而不是更精确的错误时， 要做的第一件事是检查您的代码没有吞噬异常，也没有吞噬承诺拒绝。
Mocha旨在检测您的测试中的这些。除非您执行不寻常的操作（例如在自己的VM中运行测试代码或操纵域），否则Mocha会检测到此类故障，但是如果您的代码吞噬了这些故障，Mocha将无法执行任何操作。
话虽这么说，Mocha无法告诉您
done未调用，因为您的实现存在逻辑错误，导致无法调用回调。
在
sinon测试失败后执行后期验验可以采取以下措施。让我强调，这是 概念 的 证明 。如果我想持续使用它，那么我将开发一个适当的库。
var sinon = require("sinon");var assert = require("assert");// MyEmitter is just some pre to test, created for the purpose of// illustration.var MyEmitter = require("./MyEmitter");var emitter = new MyEmitter();var postMortem;beforeEach(function () { postMortem = { calledOnce: [] };});afterEach(function () { // We perform the post mortem only if the test failed to run properly. if (this.currentTest.state === "failed") { postMortem.calledOnce.forEach(function (fn) { if (!fn.calledOnce) { // I'm not raising an exception here because it would cause further // tests to be skipped by Mocha. Raising an exception in a hook is // interpreted as "the test suite is broken" rather than "a test // failed". console.log("was not called once"); } }); }});it("client should do something", function(done) { var doneFn = function(args) { // If you change this to false Mocha will give you a useful error. This is // *not* due to the use of sinon. It is wholly due to the fact that // `MyEmitter` does not swallow exceptions. assert(true); done(); }; // We create and register our spy so that we can conduct a post mortem if the // test fails. var spy = sinon.spy(doneFn); postMortem.calledOnce.push(spy); emitter.on("foo", spy); emitter.triggerEvent("foo");});这是以下代码
MyEmitter.js：
var EventEmitter = require("events");function MyEmitter() { EventEmitter.call(this);}MyEmitter.prototype = Object.create(EventEmitter.prototype);MyEmitter.prototype.constructor = MyEmitter;MyEmitter.prototype.triggerEvent = function (event) { setTimeout(this.emit.bind(this, event), 1000);};module.exports = MyEmitter;
