使用官方的例子跑起來是沒問題的，但官方使用的是ES5的語法，沒有沒有使用ES6最新語法，嘗試了一下是不行的，在google借鑑了各種辦法才找出解決方案，記錄一下。

模擬例子

package.json檔案

{
  "name": "create-react-app",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "jss": "latest",
    "jss-preset-default": "latest",
    "material-ui": "next",
    "prop-types": "latest"
 
,
    "react": "latest",
    "react-dom": "latest",
    "react-jss": "latest",
    "react-scripts": "latest",
    "recompose": "latest"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "jest",
    "eject": "react-scripts eject"
  },
  "devDependencies
 
": {
    "babel-jest": "^21.0.2",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "enzyme": "^2.9.1",
    "expect": "^21.1.0",
    "jest": "^21.1.0",
    "jest-cli": "^21.1.0",
    "react-test-renderer": "^15.6.1"
  },
  "jest": {
    "collectCoverage": true,
    "testMatch
 
": [
      "**/__tests__/**/*.js?(x)"
    ],
    "moduleDirectories": [
      "node_modules",
      "src"
    ],
    "testPathIgnorePatterns": [
      "/node_modules/"
    ]
  }
}

React元件

import React from 'react';

const STATUS = {
    HOVERED: 'hovered',
    NORMAL: 'normal',
};

class Link extends React.Component {
//  state = {無法使用
//      class:'asdf'    
//  };

    constructor(props) {
        super(props);

        this._onMouseEnter = this._onMouseEnter.bind(this);
        this._onMouseLeave = this._onMouseLeave.bind(this);

        this.state = {
            class: STATUS.NORMAL,
            open:true
        };
    }

    _onMouseEnter () { // = () => 也無法使用
        this.setState({class: STATUS.HOVERED});
    }

    _onMouseLeave () {
        this.setState({class: STATUS.NORMAL});
    }

    render() {
        return (
            <a
                className={this.state.class}
                href={this.props.page || '#'}
                onMouseEnter={this._onMouseEnter}
                onMouseLeave={this._onMouseLeave}>
                {this.props.children}
            </a>
        );
    }

}

export default Link

Jest測試

import React from 'react';
import Link from '../src/mycomp/Link';
import renderer from 'react-test-renderer';

describe('Shallow Rendering', function () {
    it('App\'s title should be Todos', function () {
    const component = renderer.create(
        <Link page="http://www.facebook.com">Facebook</Link>
    );
    let tree = component.toJSON();

    expect(tree.type).not.toBe("b");

    expect(tree).toMatchSnapshot();

    });
});

執行jest命令出現以下錯誤

   ● Test suite failed to run

    /Users/huanghuanlai/dounine/github/material-ui/examples/create-react-app/src/mycomp/Link.js: Unexpected token (10:7)
         8 | class Link extends React.Component {
         9 |    
      > 10 |    state = {
           |          ^
        11 |        class:'asdf'    
        12 |    };

函式簡寫異常

 FAIL  __tests__/Link.js
  ● Test suite failed to run

    /Users/huanghuanlai/dounine/github/material-ui/examples/create-react-app/src/mycomp/Link.js: Unexpected token (31:15)
        29 |    }
        30 | 
      > 31 |    _onMouseLeave = () => {
           |                  ^
        32 |        this.setState({class: STATUS.NORMAL});
        33 |    }

解決方案

安裝babel-preset-stage-2元件

npm install --save-dev babel-preset-stage-2

修改.babelrc配置檔案

{
    "presets": ["es2015", "react", "stage-2"]
}