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Question

我有一个react类，它在componentDidMount中有addEventListener，如下所示：

componentDidMount() {
document.addEventListener('readystatechange', () => {
  if (document.readyState === 'complete'){
   /* Make some api call */
   /*Need to test code written here*/
  }
});
}

readystatechange事件在更改'document.readyState'时触发，document.readystate是只读的，我该如何模拟此调用？

Answer 1

我们用来测试函数内部代码的一种解决方法：

 let sandbox, addEventListener;
 sandbox = sinon.sandbox.create();
 addEventListener = sandbox.stub(document, 'addEventListener'); 
 expect(addEventListener.args[0][0]).equal('readystatechange');
 addEventListener.args[0][1](); //Call this function that has been registered to this event

 expect(api.someFunction).to.have.been.called;