node.js 测试是否使用 sinon.js 发出事件而不使用超时答案

【问题标题】：node.js testing if event was emitted using sinon.js without the use of timeoutsnode.js 测试是否使用 sinon.js 发出事件而不使用超时
【发布时间】：2016-05-14 22:32:48
【问题描述】：

我试图弄清楚当异步发出的事件已经发出时如何使用 sinon.js 进行测试？

到目前为止，我正在做的是设置一个超时时间，我知道该事件将被粗暴地发出，但这很丑陋，可能会增加测试运行的总时间，我不想这样做：

it('check that event was called', function(done) {
    ...
    var spy = sinon.spy();
    var cbSpy = sinon.spy();
    obj.on('event', spy);
    obj.func(cbSpy); // emits event 'event' asynchronously and calls cbSpy after it was emitted
    setTimeout(function() {
        sinon.assert.calledOnce(spy, 'event "event" should be emitted once');
        sinon.assert.calledOnce(cbSpy, 'func() callback should be called once'); // won't work since the callback will be called only after the event has been emitted and all event listeners finished
    }, 1000);
});

【问题讨论】：

标签： javascript node.js unit-testing mocha.js sinon

【解决方案1】：

打算尝试一下，但不使用诗乃（这里真的不需要）。

it('check that event was called', function(done) {
    var callbackCalled = false;
    var eventCalled = false;

    var checkIfDone() {
      if (callbackCalled && eventCalled) {
        done();
      }
    }

    var callbackSpy = function () {
      callbackCalled = true;
      checkIfDone();
    }

    var eventSpy = function () {
      // Spy was called.
      // Add assertions for the arguments that are passed if you want.
      eventCalled = true;
      checkIfDone();
    };

    obj.on('event', eventSpy);
    // emits event 'event' and invokes callback after it was emitted
    obj.func(callbackSpy); 
});

最好一次只测试一件事。

it('should emit `event`', function(done) {
    var callback = function () {}

    var eventSpy = function () {
      // Spy was called.
      // Add assertions for the arguments that are passed if you want.
      done()        
    };

    obj.on('event', eventSpy);
    // emits event 'event' and invokes callback after it was emitted
    obj.func(callback); 
});

it('should invoke the callback', function(done) {
    var callback = function () {
      // Callback was called.
      // Add assertions for the arguments that are passed if you want.
      done()        
    }

    obj.func(callback); 
});

在任何一种情况下，测试都将在异步进程完成后完成。我会使用第二个示例，因为这意味着您可以一次只专注于一件事，并且测试代码更加简洁。

【讨论】：