用酶测试 React 入口

Question

所以我很难使用 React fiber 的门户为模态组件编写测试。因为我的模态挂载到 <body /> 根节点上的一个 domNode 但因为那个 domNode 不存在，所以测试失败。

要提供的一些代码，上下文：

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="theme-color" content="#000000">
    <link rel="manifest" href="%PUBLIC_URL%/manifest.json">
    <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
    <title>React App</title>
  </head>
  <body>
    <noscript>
      You need to enable JavaScript to run this app.
    </noscript>
    <div id="modal-root"></div>
    <div id="root"></div>
  </body>
</html>

App.js

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';
import { Modal, ModalHeader } from './Modal';

class App extends Component {
  constructor(props) {
    super(props);
    this.state = { show: false };
    this.toggleModal = this.toggleModal.bind(this);
  }

  toggleModal(show) {
    this.setState({ show: show !== undefined ? show : !this.state.show });
  }

  render() {
    return (
      <div className="App">
        <header className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h1 className="App-title">Welcome to React</h1>
        </header>
        <p className="App-intro">
          To get started, edit <code>src/App.js</code> and save to reload.
        </p>
        <button onClick={() => this.toggleModal()}>show modal</button>
        <Modal toggle={this.toggleModal} show={this.state.show}>
          <ModalHeader>
            <span>I'm a header</span>
            <button onClick={() => this.toggleModal(false)}>
              <span aria-hidden="true">&times;</span>
            </button>
          </ModalHeader>
          <p>Modal Body!!!</p>
        </Modal>
      </div>
    );
  }
}

export default App;

Modal.js

import React, { Fragment } from 'react';
import ReactDOM from 'react-dom';
import PropTypes from 'prop-types';
// the next components are styled components, they are just for adding style no logic at all
import {
  ModalBackdrop,
  ModalContent,
  ModalDialog,
  ModalWrap,
} from './components';

class Modal extends React.Component {
  constructor(props) {
    super(props);
    this.el = document.createElement('div');
    this.modalRoot = document.getElementById('modal-root');
    this.outerClick = this.outerClick.bind(this);
  }

  componentDidMount() {
    this.modalRoot.appendChild(this.el);
    this.modalRoot.parentNode.style.overflow = '';
  }

  componentWillUpdate(nextProps) {
    if (this.props.show !== nextProps.show) {
      this.modalRoot.parentNode.style.overflow = nextProps.show ? 'hidden' : '';
    }
  }

  componentWillUnmount() {
    this.props.toggle(false);
    this.modalRoot.removeChild(this.el);
  }

  outerClick(event) {
    event.preventDefault();
    if (
      event.target === event.currentTarget ||
      event.target.nodeName.toLowerCase() === 'a'
    ) {
      this.props.toggle(false);
    }
  }

  render() {
    const ModalMarkup = (
      <Fragment>
        <ModalBackdrop show={this.props.show} />
        <ModalWrap show={this.props.show} onClick={this.outerClick}>
          <ModalDialog show={this.props.show}>
            <ModalContent>{this.props.children}</ModalContent>
          </ModalDialog>
        </ModalWrap>
      </Fragment>
    );
    return ReactDOM.createPortal(ModalMarkup, this.el);
  }
}

Modal.defaultProps = {
  show: false,
  toggle: () => {},
};

Modal.propTypes = {
  children: PropTypes.node.isRequired,
  show: PropTypes.bool,
  toggle: PropTypes.func,
};

export default Modal;

最后但并非最不重要的测试： Modal.test.js

import React from 'react';
import Modal from './Modal.component';
import {
  ModalBackdrop,
  ModalContent,
  ModalDialog,
  ModalWrap,
} from './components';

describe('Modal component', () => {
  const Child = () => <div>Yolo</div>;

  it('should render all the styled components and the children', () => {
    const component = mount(
      <Modal>
        <Child />
      </Modal>
    );
    expect(component.find(ModalBackdrop).exists()).toBeTruthy();
    expect(component.find(ModalWrap).exists()).toBeTruthy();
    expect(component.find(ModalWrap).contains(ModalDialog)).toBeTruthy();
    expect(component.find(ModalDialog).contains(ModalContent)).toBeTruthy();
    expect(component.find(ModalContent).contains(Child)).toBeTruthy();
  });
});

一个codesandbox所以你可以看到它的实际效果

Answer 1

所以经过大量的战斗，试验和希望。我设法让测试工作，秘密，在我终于记得这是一种可能性之后很明显，就是修改 jsdom 并添加我们的 domNode，我们不能忘记在每次测试后卸载组件。

Modal.test.js

import React from 'react';
import { mount } from 'enzyme';
import Modal from './Modal.component';
import {
  ModalBackdrop,
  ModalContent,
  ModalDialog,
  ModalWrap,
} from './components';

describe('Modal component', () => {
  const Child = () => <div>Yolo</div>;
  let component;

  // add a div with #modal-root id to the global body
  const modalRoot = global.document.createElement('div');
  modalRoot.setAttribute('id', 'modal-root');
  const body = global.document.querySelector('body');
  body.appendChild(modalRoot);

  afterEach(() => {
    component.unmount();
  });

  it('should render all the styled components and the children', () => {
    component = mount(
      <Modal>
        <Child />
      </Modal>,
    );
    expect(component.find(ModalBackdrop).exists()).toBeTruthy();
    expect(component.find(ModalWrap).exists()).toBeTruthy();
    expect(component.find(ModalWrap).contains(ModalDialog)).toBeTruthy();
    expect(component.find(ModalDialog).contains(ModalContent)).toBeTruthy();
    expect(component.find(ModalContent).contains(Child)).toBeTruthy();
  });

  it('should trigger toggle when clicked', () => {
    const toggle = jest.fn();
    component = mount(
      <Modal toggle={toggle}>
        <Child />
      </Modal>,
    );

    component.find(ModalWrap).simulate('click');
    expect(toggle.mock.calls).toHaveLength(1);
    expect(toggle.mock.calls[0][0]).toBeFalsy();
  });

  it('should mount modal on the div with id modal-root', () => {
    const modalRoot = global.document.querySelector('#modal-root');
    expect(modalRoot.hasChildNodes()).toBeFalsy();

    component = mount(
      <Modal>
        <Child />
      </Modal>,
    );

    expect(modalRoot.hasChildNodes()).toBeTruthy();
  });

  it('should clear the div with id modal-root on unmount', () => {
    const modalRoot = global.document.querySelector('#modal-root');

    component = mount(
      <Modal>
        <Child />
      </Modal>,
    );

    expect(modalRoot.hasChildNodes()).toBeTruthy();
    component.unmount();
    expect(modalRoot.hasChildNodes()).toBeFalsy();
  });

  it('should set overflow hidden on the boddy element', () => {
    const body = global.document.querySelector('body');
    expect(body.style.overflow).toBeFalsy();

    component = mount(
      <Modal>
        <Child />
      </Modal>,
    );

    component.setProps({ show: true });

    expect(body.style.overflow).toEqual('hidden');

    component.setProps({ show: false });
    expect(body.style.overflow).toBeFalsy();
  });
});

一件大事，就是酶还没有完全支持 React 16，github issue。理论上所有测试都应该通过，但他们仍然失败解决方案是更改模态上的包装器，而不是使用 <Fragment /> 我们需要使用旧的普通 <div />

Modal.js渲染方法：

render() {
    const ModalMarkup = (
      <div>
        <ModalBackdrop show={this.props.show} />
        <ModalWrap show={this.props.show} onClick={this.outerClick}>
          <ModalDialog show={this.props.show}>
            <ModalContent>{this.props.children}</ModalContent>
          </ModalDialog>
        </ModalWrap>
      </div>
    );
    return ReactDOM.createPortal(ModalMarkup, this.el);
  }

您可以找到包含所有代码的存储库 here

Answer 2

这可以通过模拟 createPortal 方法来简单地测试。

ReactDOM.createPortal = jest.fn(modal => modal);

let wrapper = shallow(
    <Modal visible={true}>Text</Modal>
);

expect(wrapper).toMatchSnapshot();

Answer 3

对于反应测试库有问题的任何人，这对我有用：

Modal.tsx

const domElement = React.useRef(document.getElementById('modal'));
const jsx = (<Modal>...</Modal>);
return ReactDOM.createPortal(jsx, domElement.current as HTMLElement);

Modal.test.tsx

const element = document.createElement('div');
element.setAttribute('id', 'modal');
element.setAttribute('data-testid', 'modal-test-id');

jest
    .spyOn(ReactDOM, 'createPortal')
    .mockImplementation((children, c, key) => {
        const symbol = Symbol.for('react.portal');
        return {
            $$typeof: symbol,
            key: key == null ? null : '' + key,
            children,
            containerInfo: element,
            implementation: null,
            type: symbol.description,
            props: null,
        } as ReactPortal;
    });

我不得不深入研究 react-dom 库以了解如何在我的模拟中实现 createPortal 方法，因为它不允许我 return 任何对象，它有成为 ReactPortal 对象。

来源

第110行的方法：https://github.com/facebook/react/blob/master/packages/react-dom/src/client/ReactDOM.js
在此处调用 react-reconciler 中的另一个方法：https://github.com/facebook/react/blob/master/packages/react-reconciler/src/ReactPortal.js

需要该符号来确定要使用什么类型的实现来创建元素并为此传递符号。请注意，containerInfo 是您传入可以在测试中使用的元素的地方，这样您就不必尝试包含整个 App 模块。

用酶测试 React 入口

Testing React portals with enzyme

jsdom

reactjs

jestjs

enzyme