javascript - Redux Jest 没有收到预期的值(value)

Question

我明白了

 Expected value to equal:

  [{"id": 1, "text": "Run the tests"}, {"id": 0, "text": "Use Redux"}]

Received:
  [{"id": 0, "text": "Use Redux"}, {"id": 1, "text": "Run the tests"}]

我不太明白如何让这个 reducer 测试通过。我引用了各种 github 项目来更好地理解测试。我不确定我能做些什么来使测试通过。这是我所拥有的。

我正在使用 jest 进行测试。

actions/actions.js

let nextTodoId = 0;

export const addPost = text => ({
  type: 'ADD_POST',
  id: nextTodoId++,
  text
})

reducer /myPosts

    const initialState = [
      {
        text: 'Use Redux',
        id: 0
      }
    ]



    const myPosts = (state = initialState, action) => {

      switch(action.type){
        case 'ADD_POST':
          const post = {
            id:state.reduce((maxId, post) => Math.max(post.id, maxId), -1) + 1,
            text:action.text,

          }
          return [...state, post];


        default:
          return state
      }

    }

    export default myPosts

测试/reducers.js

import { addPost } from '../actions/actions';
import myPosts from '../reducers/myPosts';
import uuid from 'uuid';
describe('myPosts myPosts', () => {
  it('should return the initial state', () => {
    expect(myPosts(undefined, {})).toEqual([
      {
        text: 'Use Redux',
        id: 0
      }
    ])
  })
  it('should handle ADD_POST', () => {
    expect(
      myPosts([], {
        type: 'ADD_POST',
        text: 'Run the tests'
      })
    ).toEqual([
      {
        text: 'Run the tests',
        id: 0
      }
    ])
    expect(
      myPosts(
        [
          {
            text: 'Use Redux',
            id: 0
          }
        ],
        {
          type: 'ADD_POST',
          text: 'Run the tests',
          id:0
        }
      )
    ).toEqual([
      {
        text: 'Run the tests',
        id: 1
      },
      {
        text: 'Use Redux',
        id: 0
      }
    ])
  })
})

Answer 1

问题是您在添加新帖子之前扩展了先前的状态...

将您的 reducer 更改为:

return [post, ...state];

您编写的方式...新帖子放置在状态数组的末尾。如果您希望新帖子首先显示，这将解决该问题。