测试调用 API 的 redux 操作

Question

测试此功能的最佳方法是什么

export function receivingItems() {
  return (dispatch, getState) => {
    axios.get('/api/items')
      .then(function(response) {
        dispatch(receivedItems(response.data));
      });
  };
}

这是我目前拥有的

describe('Items Action Creator', () => {
  it('should create a receiving items function', () => {
    expect(receivingItems()).to.be.a.function;
  });
});

Answer 1

来自 Redux “Writing Tests” 配方：

对于使用 Redux Thunk 或其他中间件的异步操作创建者，最好完全模拟 Redux 存储进行测试。您仍然可以将applyMiddleware() 与模拟商店一起使用，如下所示（您可以在redux-mock-store 中找到以下代码）。您还可以使用 nock 模拟 HTTP 请求。

function fetchTodosRequest() {
  return {
    type: FETCH_TODOS_REQUEST
  }
}

function fetchTodosSuccess(body) {
  return {
    type: FETCH_TODOS_SUCCESS,
    body
  }
}

function fetchTodosFailure(ex) {
  return {
    type: FETCH_TODOS_FAILURE,
    ex
  }
}

export function fetchTodos() {
  return dispatch => {
    dispatch(fetchTodosRequest())
    return fetch('http://example.com/todos')
      .then(res => res.json())
      .then(json => dispatch(fetchTodosSuccess(json.body)))
      .catch(ex => dispatch(fetchTodosFailure(ex)))
  }
}

可以像这样测试：

import expect from 'expect'
import { applyMiddleware } from 'redux'
import thunk from 'redux-thunk'
import * as actions from '../../actions/counter'
import * as types from '../../constants/ActionTypes'
import nock from 'nock'

const middlewares = [ thunk ]

/**
 * Creates a mock of Redux store with middleware.
 */
function mockStore(getState, expectedActions, done) {
  if (!Array.isArray(expectedActions)) {
    throw new Error('expectedActions should be an array of expected actions.')
  }
  if (typeof done !== 'undefined' && typeof done !== 'function') {
    throw new Error('done should either be undefined or function.')
  }

  function mockStoreWithoutMiddleware() {
    return {
      getState() {
        return typeof getState === 'function' ?
          getState() :
          getState
      },

      dispatch(action) {
        const expectedAction = expectedActions.shift()

        try {
          expect(action).toEqual(expectedAction)
          if (done && !expectedActions.length) {
            done()
          }
          return action
        } catch (e) {
          done(e)
        }
      }
    }
  }

  const mockStoreWithMiddleware = applyMiddleware(
    ...middlewares
  )(mockStoreWithoutMiddleware)

  return mockStoreWithMiddleware()
}

describe('async actions', () => {
  afterEach(() => {
    nock.cleanAll()
  })

  it('creates FETCH_TODOS_SUCCESS when fetching todos has been done', (done) => {
    nock('http://example.com/')
      .get('/todos')
      .reply(200, { todos: ['do something'] })

    const expectedActions = [
      { type: types.FETCH_TODOS_REQUEST },
      { type: types.FETCH_TODOS_SUCCESS, body: { todos: ['do something']  } }
    ]
    const store = mockStore({ todos: [] }, expectedActions, done)
    store.dispatch(actions.fetchTodos())
  })
})

Answer 2

我会使用一个存根axios（例如使用mock-require）并编写一个实际调用receivingItems()(dispatch, getState)的测试，并确保使用正确的数据调用dispatch。

Answer 3

我以不同的方式解决了这个问题：将 axios 作为操作的依赖项注入。我更喜欢这种方法而不是“重新布线”依赖项。

所以我使用了相同的方法来测试与 redux 连接的组件。当我导出操作时，我会导出两个版本：一个带有（用于组件）和一个不带（用于测试）绑定依赖项。

这是我的 actions.js 文件的样子：

import axios from 'axios'

export const loadDataRequest = () => {
  return {
    type: 'LOAD_DATA_REQUEST'
  }
}
export const loadDataError = () => {
  return {
    type: 'LOAD_DATA_ERROR'
  }
}
export const loadDataSuccess = (data) =>{
  return {
    type: 'LOAD_DATA_SUCCESS',
    data
  }
}
export const loadData = (axios) => {
  return dispatch => {
    dispatch(loadDataRequest())
    axios
      .get('http://httpbin.org/ip')
      .then(({data})=> dispatch(loadDataSuccess(data)))
      .catch(()=> dispatch(loadDataError()))
  }
}
export default {
  loadData: loadData.bind(null, axios)
}

然后使用jest (actions.test.js) 进行测试：

import { loadData } from './actions'

describe('testing loadData', ()=>{
  test('loadData with success', (done)=>{

    const get = jest.fn()
    const data = {
      mydata: { test: 1 }
    }
    get.mockReturnValue(Promise.resolve({data}))

    let callNumber = 0
    const dispatch = jest.fn(params =>{
      if (callNumber===0){
        expect(params).toEqual({ type: 'LOAD_DATA_REQUEST' })
      }
      if (callNumber===1){
        expect(params).toEqual({
          type: 'LOAD_DATA_SUCCESS',
          data: data
        })
        done()
      }
      callNumber++
    })
    const axiosMock = {
      get
    }
    loadData(axiosMock)(dispatch)
  })
})

在组件中使用操作时，我会导入所有内容：

import Actions from './actions'

并发送：

Actions.loadData() // this is the version with axios binded.