如何对 reduxsauce 进行单元测试？

Question

我正在使用 redux 存储库的 reduxsauce 库，我想对其中的单个 redux 存储进行单元测试。 redux 文件：

import { createReducer, createActions } from 'reduxsauce'
import Immutable from 'seamless-immutable'

/* ------------- Types and Action Creators ------------- */

const { Types, Creators } = createActions({
  getLanguage: [],
  setLanguage: ['language']
})

export const LanguageTypes = Types
export default Creators

/* ------------- Initial State ------------- */

export const INITIAL_STATE = Immutable({
  language: "en"
})

/* ------------- Reducers ------------- */


export const getLanguage = (state: Object, {}: Object) => {
    return state.merge({})
}

export const setLanguage = (state: Object, { language }: Object) => {
    return state.merge({ language })
}

/* ------------- Hookup Reducers To Types ------------- */

export const reducer = createReducer(INITIAL_STATE, {
  [Types.SET_LANGUAGE]: setLanguage,
  [Types.GET_LANGUAGE]: getLanguage,
})

测试：

import * as actions from '../../../redux/LanguageRedux'
import * as types from '../../../redux/LanguageRedux'

describe('Language redux ', () => {
  it('should have default language ', () => {
    expect(actions.INITIAL_STATE.language).toEqual("en")
  }),
  it('should be able to set the language', () => {
    // I know the calls below are not tests but still its relevant with the error
    actions.getLanguage()
    actions.setLanguage()
  })
})

错误：

● Language redux  › should be able to set the language

    TypeError: Cannot destructure 'undefined' or 'null'.

      21 |
      22 |
    > 23 | export const getLanguage = (state: Object, {}: Object) => {
         |                            ^
      24 |     return state.merge({})
      25 | }
      26 |

      at Object.getLanguage (src/redux/LanguageRedux.js:23:28)
      at Object.getLanguage (src/__tests__/src/redux/LanguageRedux.js:9:13)

现在，我在不同的文件中配置了 store，但 reducers 组合在了不同的文件中：

import { combineReducers } from 'redux'
import configureStore from './CreateStore'

import rootSaga from '../sagas'

export default () => {
    /* ------------- Assemble The Reducers ------------- */
    const rootReducer = combineReducers({
        language: require('./LanguageRedux').reducer
    })

    return configureStore(rootReducer, rootSaga)
}

任何人都知道如何测试 redux 操作等。使用普通的 redux，我可以找到很多文章，但使用 reduxsauce 库，我似乎找不到任何东西。请问有什么线索吗？

Answer 1

正在测试什么

LanguageRedux.js 具有以下导出：

• LanguageTypes - 动作类型的映射
• Creators - 动作创建者地图
• INITIAL_STATE - 应用的初始状态
• getLanguage 和 setLanguage - reducer 函数
• reducer - redux 减速器

我建议使用这样的预期标识符导入所有内容：

import Creators, {
  LanguageTypes,
  INITIAL_STATE,
  getLanguage,
  setLanguage,
  reducer
 } from '../../../redux/LanguageRedux';

注意：看起来getLanguage 操作是不必要的，因为它对状态没有任何作用（如果应用正在获取语言，它应该从状态中读取它），但我'将它留在那里，因为它在问题代码中。

---

语言类型

LanguageTypes 只是动作类型与其相关字符串值的映射：

it('should export the expected action types', () => {
  expect(LanguageTypes).toEqual({
    GET_LANGUAGE: 'GET_LANGUAGE',
    SET_LANGUAGE: 'SET_LANGUAGE'
  });  // Success!
});

---

创作者

Creators 是动作创建者的地图。

每个动作创建者都是一个纯函数，它根据给定的参数生成一个动作对象：

describe('Creators', () => {

  describe('getLanguage', () => {

    it('should return the expected action', () => {
      expect(Creators.getLanguage()).toEqual({
        type: LanguageTypes.GET_LANGUAGE
      });
    });

    it('should ignore extra args', () => {
      expect(Creators.getLanguage('extra arg')).toEqual({
        type: LanguageTypes.GET_LANGUAGE
      });
    });

  });

  describe('setLanguage', () => {

    it('should return the expected action when passed nothing', () => {
      expect(Creators.setLanguage()).toEqual({
        type: LanguageTypes.SET_LANGUAGE
      });  // Success!
    });

    it('should return the expected action when passed a language', () => {
      expect(Creators.setLanguage('en')).toEqual({
        type: LanguageTypes.SET_LANGUAGE,
        language: 'en'
      });  // Success!
    });

    it('should ignore extra args', () => {
      expect(Creators.setLanguage('es', 'extra arg')).toEqual({
        type: LanguageTypes.SET_LANGUAGE,
        language: 'es'
      });  // Success!
    });

  });

});

---

INITIAL_STATE

INITIAL_STATE 只是应用启动的初始状态对象：

it('should set the initial state ', () => {
  expect(INITIAL_STATE).toEqual({ language: "en" });  // Success!
});

---

reducer 函数

getLanguage 和 setLanguage 是 reducer 函数，这意味着它们是纯函数，它们根据给定的现有状态和动作返回新状态：

describe('reducers', () => {

  describe('getLanguage', () => {

    it('should do nothing (probably should not be an action)', () => {
      expect(getLanguage(INITIAL_STATE, {})).toEqual(INITIAL_STATE);  // Success!
    });

    it('should ignore extra args', () => {
      expect(getLanguage(INITIAL_STATE, { extra: 'arg' })).toEqual(INITIAL_STATE);  // Success!
    });

  });

  describe('setLanguage', () => {

    it('should set the language', () => {
      expect(setLanguage(INITIAL_STATE, { language: 'es' })).toEqual({
        language: 'es'
      });  // Success!
    });

    it('should ignore extra args', () => {
      expect(setLanguage(INITIAL_STATE, { language: 'fr', extra: 'arg' })).toEqual({
        language: 'fr'
      });  // Success!
    });

  });

});

请注意，使用reduxsauce 测试reducer 函数比测试标准redux reducer 更容易，因为它们仅会被调用以处理它们设计的操作。

---

减速器

reducer 是 redux reducer，它的工作是将 action 路由到相应的 reducer 函数并返回结果状态：

describe('reducer', () => {

  it('should return initial state if passed nothing', () => {
    expect(reducer()).toEqual(INITIAL_STATE);  // Success!
  });

  it('should route GET_LANGUAGE to getLanguage', () => {
    expect(reducer(INITIAL_STATE, Creators.getLanguage())).toEqual(INITIAL_STATE);  // Success!
  });

  it('should route SET_LANGUAGE to setLanguage', () => {
    expect(reducer(Immutable({ language: 'es' }), Creators.setLanguage('fr'))).toEqual({
      language: 'fr'
    });  // Success!
  });

});

注意：有几种不同的方法可以测试reducer。上述方法通过 reducer 函数一直传递状态和动作。很彻底，但和上面的reducer功能测试也有很多重叠。

最基本的替代方法是监视createReducer，并简单地验证它是使用预期的INITIAL_STATE 和映射对象调用的。

介于上述方法和完整方法之间的方法是模拟 reducer 函数，传递 reducer 各种操作，并验证是否调用了正确的 reducer 函数。这可能是理想的方法，但很难实现当前编写代码的方式，因为createReducer 在代码导入后立即运行并捕获对本地函数setLanguage 和@ 的引用987654349@。如果您想使用这种方法，那么最简单的方法是将reducer 移动到它自己的模块中，这样您就可以在将reducer 导入您的测试代码之前模拟化简函数。