如果你正在寻找一个mock而不是存根，这是我使用的解决方案:

export const localStorageMock = {
   getItem: jest.fn().mockImplementation(key => localStorageItems[key]),
   setItem: jest.fn().mockImplementation((key, value) => {
       localStorageItems[key] = value;
   }),
   clear: jest.fn().mockImplementation(() => {
       localStorageItems = {};
   }),
   removeItem: jest.fn().mockImplementation((key) => {
       localStorageItems[key] = undefined;
   }),
};

export let localStorageItems = {}; // eslint-disable-line import/no-mutable-exports

为了便于初始化，我导出了存储项。例如，我可以很容易地将它设置为一个对象

在Jest + JSDom的新版本中，不可能设置这个，但是本地存储已经可用，你可以像这样监视它:

const setItemSpy = jest.spyOn(Object.getPrototypeOf(window.localStorage), 'setItem');

或者你只是像这样使用一个模拟包:

https://www.npmjs.com/package/jest-localstorage-mock

它不仅处理存储功能，还允许您测试是否实际调用了存储。

describe('getToken', () => {
    const Auth = new AuthService();
    const token = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VybmFtZSI6Ik1yIEpvc2VwaCIsImlkIjoiNWQwYjk1Mzg2NTVhOTQ0ZjA0NjE5ZTA5IiwiZW1haWwiOiJ0cmV2X2pvc0Bob3RtYWlsLmNvbSIsInByb2ZpbGVVc2VybmFtZSI6Ii9tcmpvc2VwaCIsInByb2ZpbGVJbWFnZSI6Ii9Eb3Nlbi10LUdpci1sb29rLWN1dGUtbnVrZWNhdDMxNnMtMzExNzAwNDYtMTI4MC04MDAuanBnIiwiaWF0IjoxNTYyMzE4NDA0LCJleHAiOjE1OTM4NzYwMDR9.YwU15SqHMh1nO51eSa0YsOK-YLlaCx6ijceOKhZfQZc';
    beforeEach(() => {
        global.localStorage = jest.fn().mockImplementation(() => {
            return {
                getItem: jest.fn().mockReturnValue(token)
            }
        });
    });
    it('should get the token from localStorage', () => {

        const result  = Auth.getToken();
        expect(result).toEqual(token);

    });
});

创建一个模拟并将其添加到全局对象

2021年,打印稿

class LocalStorageMock {
  store: { [k: string]: string };
  length: number;

  constructor() {
    this.store = {};
    this.length = 0;
  }

  /**
   * @see https://developer.mozilla.org/en-US/docs/Web/API/Storage/key
   * @returns
   */
  key = (idx: number): string => {
    const values = Object.values(this.store);
    return values[idx];
  };

  clear() {
    this.store = {};
  }

  getItem(key: string) {
    return this.store[key] || null;
  }

  setItem(key: string, value: string) {
    this.store[key] = String(value);
  }

  removeItem(key: string) {
    delete this.store[key];
  }
}

export default LocalStorageMock;

然后你可以用它

global.localStorage = new LocalStorageMock();

在我的例子中，我需要在检查localStorage值之前设置它。

我所做的就是

const data = { .......}

const setLocalStorageValue = (name: string, value: any) => {
  localStorage.setItem(name, JSON.stringify(value))
}



 describe('Check X class', () => {
  setLocalStorageValue('Xname', data)
  const xClass= new XClass()

  console.log(xClass.initiate()) ; // it will work 

  
})

不幸的是，我在这里找到的解决方案对我不起作用。

所以我在看Jest GitHub的问题，发现了这个帖子

得到最多好评的解决方案是:

const spy = jest.spyOn(Storage.prototype, 'setItem');

// or

Storage.prototype.getItem = jest.fn(() => 'bla');