养成良好的编码习惯,一个合格的程序员需要掌握一些编写单元测试的能力。单元测试也可以整体上提升我们的代码质量,这里介绍下 VUE 组件的单元测试。
如果想直接通过 Demo 学习,可以跳过下面的内容,点击这里下载示例
技术栈
- @vue/test-utils[1.0.0-beta.30]
- istanbul-instrumenter-loader[3.0.1]
- karma[4.4.1]
- karma-chrome-launcher[3.1.0]
- karma-mocha[1.3.0]
- karma-sourcemap-loader[0.3.7]
- karma-coverage-istanbul-reporter[2.1.1]
- karma-webpack[4.0.2]
- webpack[4.41.5]
定义配置文件
karma.conf.js 文件用于 karma 的配置,使用 node_modules/.bin/karma init 命令创建该文件,我们定义如下配置:
// Karma configurationconst webpackConfig = require('./config/webpack.test.config.js')module.exports = function(config) { config.set({ // base path that will be used to resolve all patterns (eg. files, exclude) basePath: '.', // frameworks to use // available frameworks: https://npmjs.org/browse/keyword/karma-adapter frameworks: [ 'mocha' ], // list of files / patterns to load in the browser files: [ 'test*.spec.js' ], // preprocess matching files before serving them to the browser // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor preprocessors: { 'test*.spec.js': [ 'webpack', 'sourcemap' ] }, // webpack config webpack: webpackConfig, webpackMiddleware: { stats: 'errors-only' }, // web server port port: 9876, // enable / disable colors in the output (reporters and logs) colors: true, // level of logging // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG logLevel: config.LOG_INFO, // enable / disable watching file and executing tests whenever any file changes autoWatch: true, // start these browsers // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher browsers: [ 'Chrome' ], // Continuous Integration mode // if true, Karma captures browsers, runs the tests and exits singleRun: false, // Concurrency level // how many browser should be started simultaneous concurrency: Infinity })}编写测试用例
详细的关于 @vue/test-utils 用法,查看 https://vue-test-utils.vuejs.org/zh/
import { expect } from 'chai'import { shallowMount } from '@vue/test-utils'import Header from '../src/components/Header'describe('Header', () => { const wrapper = shallowMount(Header) const header = wrapper.find('header') const h1 = wrapper.find('h1') it('有 header 标签', () => { expect(header.exists()).to.be.true }) it('有 h1 标签', () => { expect(h1.exists()).to.be.true }) it('h1 的文案为“VUE 单页模版”', () => { expect(h1.text()).to.equal('VUE 单页模版') }) it('h1 标签在 header 标签中', () => { expect(header.contains('h1')).to.be.true })})这里我引用 vue-single-page 的 Header 组件测试用例
运行结果
i 「wdm」: Compiled successfully.
15 01 2020 18:28:13.799:INFO [karma-server]: Karma v4.4.1 server started at http://0.0.0.0:9876/
15 01 2020 18:28:13.813:INFO [launcher]: Launching browsers Chrome with concurrency unlimited
15 01 2020 18:28:13.820:INFO [launcher]: Starting browser Chrome
15 01 2020 18:28:17.075:INFO [Chrome 79.0.3945 (Windows 10.0.0)]: Connected on socket PUKPz4iBuFzeVNSsAAAA with id 91716917
TOTAL: 4 SUCCESS
可以看到我们的单元测试已经通过了
测试覆盖率报告
测试完成后,我们需要查看测试覆盖率报告。这需要在 webpack.test.config.js 和 karma.conf.js 中做一些配置修改
webpack.test.config.js
添加一个优先执行的编译 .spec.js 文件的 rules,loader 使用 istanbul-instrumenter-loader 并开启 esModules 模式
karma.conf.js
运行结果
再次执行单元测试,我们会看到测试覆盖率的相关信息
----------------|----------|----------|----------|----------|-------------------|File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |----------------|----------|----------|----------|----------|-------------------|All files | 100 | 100 | 100 | 100 | | Header.spec.js | 100 | 100 | 100 | 100 | |----------------|----------|----------|----------|----------|-------------------|也可以通过生成到 coverage 目录下的网页文件,在浏览器中查看
参考资料
https://vue-test-utils.vuejs.org/zh/
https://github.com/mattlewis92/karma-coverage-istanbul-reporter
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。