karma与webpack结合

一、必备插件

1.babel：es6的语法支持

2.karma：测试框架

3.jasmine：断言框架

4.webpack:打包工具

5.karma-webpack：karma调用webpack打包接口的插件

二、实现步骤

1.通过npm安装上述必备的插件包

2.创建webpack.test.config.js文件，此文件的配置用于单元测试

var path = require('path');
var webpack = require('webpack');
module.exports={
    module:{
        loaders:[{
            test:/\.js$/,
            loader:'babel',
            query:{
                presets:['es2015']
            },
            exclude:[
               path.resolve( __dirname, '../test' ), path.resolve( __dirname, '../node_modules' )
            ]
        }]
    }
};

注意：

1.此配置参数中没有entry、output两个节点的配置，打包的输入和输出karma会指定

3. 通过karma init命令创建karma.conf.js配置文件

此文件创建好之后，手动添加对webpack.test.config.js文件的引用，且需要增加如下节点：

1.webpack：设置webpack相关配置参数，也就是导入的webpack.test.config.js的对象

2.webpackMiddleware：设置webpack-dev-middleware（实现webpack的打包，但可以控制输入和输出）插件的相关参数

3.preprocessors：增加对webpack引用。

var webpackConfig = require('./webpack.test.config');
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: ['jasmine'],

    // list of files / patterns to load in the browser
    files: [
        '../test/index.js'
    ],

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

    // preprocess matching files before serving them to the browser
    // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
    preprocessors: {
      '../test/index.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: webpackConfig,
    webpackMiddleware:{
      noInfo:false
    }
  })
}

注意：配置的files与preprocessors节点都是指向单元测试的入口文件(test/index.js)

4.创建需要测试的源码与单元测试文件

1.src/cache/index.js：cache模块导出接口，本次只导出的memoryCache.js，代码如下：

export { default as MemoryCache } from './memoryCache';

2.src/cache/memoryCache.js：实现缓存数据的操作，也是需要单元测试的类，代码如下：

export default class MemoryCache extends abCache{
    constructor( limit ){
        super( limit );
        this._map = [];
    }
}
var p = MemoryCache.prototype;
p.push = function(key, item){
    var entry = {
        key: key,
        value: item
    };
    this._map.push(entry);
};
p.get = function(key,ruturnEntry){
    for(let item of this._map){
        if(item.key == key){
            return ruturnEntry ? item.value : item;
        }
    }
    return null;
};
p.remove = function(key){
    for(let index in this._map){
        if(this._map[index].key == key){
            this._map.splice(index,1);
            return;
        }
    }
}

3.test/cache/memoryCacheTest.js：单元测试用例类

var _memory = require('../../src/cache/index.js').MemoryCache;
describe('memoryCache test',function(){
    var _memeoryCache;
    _memeoryCache = new _memory();
    beforeEach(function(){ //每运行一个it时，之前执行
    });
    it('push',function(){
        var foo = {"name":"foo.Name"};
        _memeoryCache.push("foo",foo);
        var _destFoo = _memeoryCache.get('foo',true);
        expect(_destFoo).toBe(foo);
    });
    it('get', function(){
       expect(_memeoryCache.get('foo',true)).not.toBeNull();
    });
    it('remove',function(){
        _memeoryCache.remove('foo');
        expect(_memeoryCache.get('foo')).toBeNull();
    });
});

4.test/index.js：单元测试的入口文件

require('./cache/memoryCahceTest.js');

5. karma start运行单元测试即可。