前端组件单选测试Jest + Enzyme

技术选型：Jest + Enzyme

Jest

www.jestjs.cn

Jest是Facebook开源的一个前端测试框架，主要用于React和React Native的单元测试，已被集成在create-react-app中。Jest特点：

易用性：基于Jasmine，提供断言库，支持多种测试风格
适应性：Jest是模块化、可扩展和可配置的
沙箱和快照：Jest内置了JSDOM，能够模拟浏览器环境，并且并行执行
快照测试：Jest能够对React组件树进行序列化，生成对应的字符串快照，通过比较字符串提供高性能的UI检测
Mock系统：Jest实现了一个强大的Mock系统，支持自动和手动mock
支持异步代码测试：支持Promise和async/await
自动生成静态分析结果：内置Istanbul，测试代码覆盖率，并生成对应的报告

下面是一个使用Jest进行单元测试的例子：

javascript 复制代码

// sum.js
function sum(a, b) {
  return a + b;
}
module.exports = sum;

// sum.test.js
const sum = require('./sum');

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

Enzyme

enzymejs.github.io/enzyme/

Enzyme是Airbnb开源的React测试工具库库，它功能过对官方的测试工具库ReactTestUtils的二次封装，提供了一套简洁强大的 API，并内置Cheerio，实现了jQuery风格的方式进行DOM 处理，开发体验十分友好。在开源社区有超高人气，同时也获得了React 官方的推荐。

下面是一个使用Enzyme进行单元测试的例子：

javascript 复制代码

import React from 'react';
import { shallow } from 'enzyme';
import MyComponent from './MyComponent';

describe('MyComponent', () => {
  it('renders correctly', () => {
    const wrapper = shallow(<MyComponent />);
    expect(wrapper).toMatchSnapshot();
  });

  it('increments the count when the button is clicked', () => {
    const wrapper = shallow(<MyComponent />);
    const button = wrapper.find('button');
    button.simulate('click');
    expect(wrapper.state('count')).toEqual(1);
  });
});

约定

推荐按照业界通用实践的规范，我们有如下约定：

单元测试的代码放置在 tests 目录下
单元测试文件命名格式使用 xxx.test.ts

遇到的问题

因为uuid只提供ESM浏览器导出，而不提供CommonJS导出出现了下面的报错，详情见下面的git链接
github.com/uuidjs/uuid...

javascript 复制代码

  /jest-bug/node_modules/uuid/dist/esm-browser/index.js:1
   ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export { default as v1 } from './v1.js';
                                                                                     ^^^^^^

   SyntaxError: Unexpected token 'export'

   > 1 | import { v4 } from "uuid";
       | ^
     2 | import { nanoid } from "nanoid";
     3 |
     4 | export function getUuid() {

     at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1773:14)

解决办法

github.com/jestjs/jest...
github.com/microsoft/a...

javascript 复制代码

// https://github.com/jestjs/jest/issues/12770
// https://github.com/microsoft/accessibility-insights-web/pull/5421/commits/9ad4e618019298d82732d49d00aafb846fb6bac7
module.exports = (path, options) =>
  // Call the defaultResolver, so we leverage its cache, error handling, etc.
  options.defaultResolver(path, {
    ...options,
    // Use packageFilter to process parsed `package.json` before the resolution (see https://www.npmjs.com/package/resolve#resolveid-opts-cb)
    packageFilter: (pkg) => {
      // This is a workaround for https://github.com/uuidjs/uuid/pull/616
      //
      // jest-environment-jsdom 28+ tries to use browser exports instead of default exports,
      // but uuid only offers an ESM browser export and not a CommonJS one. Jest does not yet
      // support ESM modules natively, so this causes a Jest error related to trying to parse
      // "export" syntax.
      //
      // This workaround prevents Jest from considering uuid's module-based exports at all;
      // it falls back to uuid's CommonJS+node "main" property.
      //
      // Once we're able to migrate our Jest config to ESM and a browser crypto
      // implementation is available for the browser+ESM version of uuid to use (eg, via
      // https://github.com/jsdom/jsdom/pull/3352 or a similar polyfill), this can go away.
      if (pkg.name === 'uuid') {
        delete pkg.exports;
        delete pkg.module;
      }
      return pkg;
    },
  });

前端组件单选测试Jest + Enzyme

Jest

Enzyme

约定

相关配置

遇到的问题

相关框架