如何获得减速机单元测试工作？

Question

试图为我的redux reducer为购物车创建一个单元测试。这是减速，该项目被添加到项目属性：

const initialState = { 
    items: [], 
    cartOpen: false, 
    newMonthlyCost: 0, 
    currentMonthlyCost: 0, 
    showNextButton: false, 
    orderConfirmed: false 
} 

const Cart = (state = initialState, action) => { 
    switch (action.type) { 
     case 'ADD_TO_CART': 
      return Object.assign({}, state, 
       { 
        items: [...state.items,action.data] 
       }); 

     default: 
      return state 
    } 
} 


export default Cart 

我钗单元测试是这样的：

import reducer from './../../foss-frontend/app/reducers/cart.js' 
import {expect} from 'chai'; 

describe('cart reducer',() => { 

    it('should handle ADD_TO_CART',() => { 
     expect(
      reducer([], { 
       type: 'ADD_TO_CART', 
       data: { 
        id: 12, price: 2332 
       } 
      }) 
     ).to.deep.equal({items: [{id: 124, price: 2332}]}) 
    }) 
}) 

为什么会出现这种错误，以及如何解决这一问题？

错误：

 TypeError: Cannot convert undefined or null to object 
     at Function.from (native) 
     at _toConsumableArray (app\reducers\cart.js:7:182) 

Answer 1

您拨打tetsts减速机采用空数组作为国家

reducer([], {...}) 

所以state.items是不确定的。然后你尝试解构它

items: [...state.items,action.data] 

并得到这个错误。

请检查state.items存在 - 这样的，比如

const Cart = (state = initialState, action) => { 
    switch (action.type) { 
     case 'ADD_TO_CART': 
      const { items=[] } = state; 
      return Object.assign({}, state, 
       { 
        items: [...items,action.data] 
       }); 

     default: 
      return state 
    } 
}