至少到目前为止，localStorage可以很容易地在你的笑话测试中被监视，例如:

const spyRemoveItem = jest.spyOn(window.localStorage, 'removeItem')

就是这样。你可以像以前一样使用你的间谍。

在这里引用了一些其他的答案来解决一个用Typescript的项目。我像这样创建了一个LocalStorageMock:

export class LocalStorageMock {

    private store = {}

    clear() {
        this.store = {}
    }

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

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

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

然后我创建了一个LocalStorageWrapper类，我使用它来访问应用程序中的所有本地存储，而不是直接访问全局本地存储变量。便于在包装器中为测试设置模拟。

Object.defineProperty(window, "localStorage", {
  value: {
    getItem: jest.fn(),
    setItem: jest.fn(),
    removeItem: jest.fn(),
  },
});

or

jest.spyOn(Object.getPrototypeOf(localStorage), "getItem");
jest.spyOn(Object.getPrototypeOf(localStorage), "setItem");

正如@ck4所建议的那样，文档已经清楚地解释了如何使用localStorage。然而，模拟函数无法执行任何localStorage方法。

下面是我的react组件的详细示例，它使用抽象方法来写入和读取数据，

//file: storage.js
const key = 'ABC';
export function readFromStore (){
    return JSON.parse(localStorage.getItem(key));
}
export function saveToStore (value) {
    localStorage.setItem(key, JSON.stringify(value));
}

export default { readFromStore, saveToStore };

错误:

TypeError: _setupLocalStorage2.default.setItem is not a function

解决办法: 为jest添加以下mock函数(路径:.jest/mocks/setUpStore.js)

let mockStorage = {};

module.exports = window.localStorage = {
  setItem: (key, val) => Object.assign(mockStorage, {[key]: val}),
  getItem: (key) => mockStorage[key],
  clear: () => mockStorage = {}
};

Snippet从这里引用

至少到目前为止，localStorage可以很容易地在你的笑话测试中被监视，例如:

const spyRemoveItem = jest.spyOn(window.localStorage, 'removeItem')

就是这样。你可以像以前一样使用你的间谍。

上面的答案对我都没用。经过一番挖掘，这就是我要做的。这要归功于一些来源和其他答案。

https://www.codeblocq.com/2021/01/Jest-Mock-Local-Storage/ https://github.com/facebook/jest/issues/6798#issuecomment-440988627 https://gist.github.com/mayank23/7b994385eb030f1efb7075c4f1f6ac4c https://github.com/facebook/jest/issues/6798#issuecomment-514266034

我的全部要点:https://gist.github.com/ar-to/01fa07f2c03e7c1b2cfe6b8c612d4c6b

/**
 * Build Local Storage object
 * @see https://www.codeblocq.com/2021/01/Jest-Mock-Local-Storage/ for source
 * @see https://stackoverflow.com/a/32911774/9270352 for source
 * @returns
 */
export const fakeLocalStorage = () => {
  let store: { [key: string]: string } = {}

  return {
    getItem: function (key: string) {
      return store[key] || null
    },
    setItem: function (key: string, value: string) {
      store[key] = value.toString()
    },
    removeItem: function (key: string) {
      delete store[key]
    },
    clear: function () {
      store = {}
    },
  }
}

/**
 * Mock window properties for testing
 * @see https://gist.github.com/mayank23/7b994385eb030f1efb7075c4f1f6ac4c for source
 * @see https://github.com/facebook/jest/issues/6798#issuecomment-514266034 for sample implementation
 * @see https://developer.mozilla.org/en-US/docs/Web/API/Window#properties for window properties
 * @param { string } property window property string but set to any due to some warnings
 * @param { Object } value for property
 *
 * @example
 *
 *  const testLS = {
 *    id: 5,
 *    name: 'My Test',
 *  }
 * mockWindowProperty('localStorage', fakeLocalStorage())
 * window.localStorage.setItem('currentPage', JSON.stringify(testLS))
 *
 */
const mockWindowProperty = (property: string | any, value: any) => {
  const { [property]: originalProperty } = window
  delete window[property]
  beforeAll(() => {
    Object.defineProperty(window, property, {
      configurable: true,
      writable: true,
      value,
    })
  })
  afterAll(() => {
    window[property] = originalProperty
  })
}

export default mockWindowProperty