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Mocking a Module's Dependencies of webpack

Jan 17, 2016

最近的项目中使用了 webpack 及 karma 进行单元测试,遇到的问题是如何 mocking 需测试模块中的 dependencies.

Kentor 的文章给了答案:

One way to achieve this is to use rewire and its webpack version rewire-webpack. Rewire can be used to change private variables in a module.

安装

npm i rewire rewire-webpack --save-dev

配置

// karma.conf.js
var RewirePlugin = require('rewire-webpack');

module.exports = function(config) {

  config.set({
    ...
    webpack: {
      // webpack configuration
      plugins: [
        new RewirePlugin()
      ]
    }
  });
};

测试

// module.js
var ActionModal = require('./ActionModal');

module.exports = {
  alert: function(msg) {
    ActionModal.alert(msg);
  }
};

// spec.js
var rewire = require('rewire');

describe('module', function() {

  var module = rewire('./module');
  var ActionModal = jasmine.createSpyObj('ActionModal', ['alert']);
  module.__set__('ActionModal', ActionModal);

  it('alert', function() {
    module.alert('msg');
    expect(ActionModal.alert).toHaveBeenCalledWith('msg');
  });
});

Enjoy it!