React - Jest - Enzyme:如何模拟 ref 属性 [英] React - Jest - Enzyme: How to mock ref properties

问题描述

我正在为带有 ref 的组件编写测试.我想模拟 ref 元素并更改一些属性，但不知道如何操作.有什么建议吗?

//MyComp.jsxclass MyComp 扩展了 React.Component {构造函数(道具){超级(道具)；this.getRef = this.getRef.bind(this);}componentDidMount() {this.setState({elmHeight: this.elm.offsetHeight});}获取引用(榆树){this.elm = 榆树;}使成为() {返回 
<span ref={getRef}>里面的东西</span>
}}//MyComp.test.jsxconst comp = mount();//由于不在浏览器中，offsetHeight为0//在这里模拟 ref offsetHeight 为 100... 怎么做?期望(comp.state('elmHeight')).toEqual(100);

解决方案

所以这里是解决方案，根据讨论https://github.com/airbnb/enzyme/issues/1937

可以使用非箭头函数对类进行猴子修补，其中this"关键字被传递到正确的作用域.

function mockGetRef(ref:any) {this.contentRef = {offsetHeight: 100}}jest.spyOn(MyComp.prototype, 'getRef').mockImplementationOnce(mockGetRef);const comp = mount();期望(comp.state('contentHeight')).toEqual(100);

I'm writing test for a component with ref. I'd like to mock the ref element and change some properties but have no idea how to. Any suggestions?

// MyComp.jsx
class MyComp extends React.Component {
  constructor(props) {
    super(props);
    this.getRef = this.getRef.bind(this);
  }
  componentDidMount() {
    this.setState({elmHeight: this.elm.offsetHeight});
  }
  getRef(elm) {
    this.elm = elm;
  }
  render() {
    return <div>
      <span ref={getRef}>
        Stuff inside 
      </span>
    </div>
  }
}

// MyComp.test.jsx
const comp = mount(<MyComp />);
// Since it is not in browser, offsetHeight is 0
// mock ref offsetHeight to be 100 here... How to?
expect(comp.state('elmHeight')).toEqual(100);

解决方案

So here's the solution, according to discussion in https://github.com/airbnb/enzyme/issues/1937

It is possible to monkey-patch the class with a non-arrow function, where "this" keyword is passed to the right scope.

function mockGetRef(ref:any) {
  this.contentRef = {offsetHeight: 100}
}
jest.spyOn(MyComp.prototype, 'getRef').mockImplementationOnce(mockGetRef);
const comp = mount(<MyComp />);
expect(comp.state('contentHeight')).toEqual(100);

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