为什么在React单元测试中的模拟事件中使用sinon.spy模拟函数和React Component的asen.shallow渲染时，这是未定义的？

Question

Whenever I try to simulate an event where I am passing the event object, I am getting that this is undefined .

const onBlur = sinon.spy(Input.prototype.handleBlur);
const wrapper = shallow(<Input handleBlur={onBlur} />);
//...
wrapper.find('input').simulate('blur', { target: {value: ''} });

Inside of the handleBlur method, this is undefined. However, if I decide not to mock the event object, then event is undefined.

Also, I tried using mount instead: const wrapper = shallow(<Input handleBlur={onBlur} />); But, it's the same thing. However, I couldn't even get to that point until I updated the npm libraries.

Answer 1

try using

const onBlur = sinon.spy(Input.prototype, "handleBlur");

instead

const onBlur = sinon.spy(Input.prototype.handleBlur);