【前端单元测试入门04】Karma

Karma

官方介绍

A simple tool that allows you to execute JavaScript code in multiple real browsers.

即一个允许你在多个真实浏览器中执行js代码的简单工具。
使用了karma之后，我们之前为了Enzyme的mount而要求的环境就不需要用jsdom去模拟了，因为karma就是将测试js在真实浏览器中执行的。

安装：

npm i --save-dev karma karma-chai karma-webpack karma-mocha karma-chrome-launcher
npm i karma -g
npm install -g karma-cli //window命令行运行，如果显示不能发现webpack那么需要安装这个

然后配置karma：

karma init

以下为我的配置：

// Karma configuration
// Generated on Fri Feb 02 2018 10:07:20 GMT+0800 (中国标准时间)

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','chai'],


    // list of files / patterns to load in the browser
    files: [
      'src/**/*.js',
      'src/**/*.jsx',//不知道为什么，karma无法识别jsx
      'test/*.test.js'
    ],


    // list of files / patterns to exclude
    exclude: [],


    // preprocess matching files before serving them to the browser
    // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
    preprocessors: {
      'src/**/*.js': ['webpack'],
      //'src/**/*.jsx':['webpack'],//不知道为什么，karma无法识别jsx
      'test/*.test.js': ['webpack']
    },


    // test results reporter to use
    // possible values: 'dots', 'progress'
    // available reporters: https://npmjs.org/browse/keyword/karma-reporter
    reporters: ['progress'],

    // 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,
    webpack: {
      module: {
        rules: [{
            test: /\.jsx?$/,
            exclude: /(node_modules)/,
            use: {
              loader: 'babel-loader',
              options: {
                presets: ['env', 'react']
              }
            }
          },
          {
            test: /\.(gif|png|jpe?g|svg)$/i,
            use: [{
              loader: 'file-loader',
              options: {
                  name: '[name].[ext]',
                  outputPath: 'images/'
              }
            }]
          },
          {
            test: /\.css$/,
            use: ['style-loader', 'css-loader']
          },
          {
            test: /\.less$/,
            use: ['style-loader', 'css-loader', 'less-loader']
          }
        ]
      }
    }
    })
}

一点小疑惑，在用kamar的时候正则表达式匹配不到jsx文件，于是将项目内部的jsx文件都改为js就好了。

因为更喜欢jest的方式，所以对karma这种使用到浏览器的没有做更深入的研究，只是有所了解就够了。