你可以使用这种方法来避免嘲笑。

Storage.prototype.getItem = jest.fn(() => expectedPayload);

以下解决方案兼容更严格的TypeScript、ESLint、TSLint和Prettier配置测试:{"proseWrap": "always"， "semi": false， "singleQuote": true， "trailingComma": "es5"}:

class LocalStorageMock {
  public store: {
    [key: string]: string
  }
  constructor() {
    this.store = {}
  }

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

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

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

  public removeItem(key: string) {
    delete this.store[key]
  }
}
/* tslint:disable-next-line:no-any */
;(global as any).localStorage = new LocalStorageMock()

HT/ https://stackoverflow.com/a/51583401/101290了解如何更新global.localStorage

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();

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');

要在Typescript中做同样的事情，请执行以下步骤:

设置一个包含以下内容的文件:

let localStorageMock = (function() {
  let store = new Map()
  return {

    getItem(key: string):string {
      return store.get(key);
    },

    setItem: function(key: string, value: string) {
      store.set(key, value);
    },

    clear: function() {
      store = new Map();
    },

    removeItem: function(key: string) {
        store.delete(key)
    }
  };
})();
Object.defineProperty(window, 'localStorage', { value: localStorageMock });

然后将以下行添加到包中。json在你的Jest配置

:“setupTestFrameworkScriptFile PATH_TO_YOUR_FILE”,

或者在您想要模拟本地存储的测试用例中导入该文件。

不需要模拟localStorage—只需使用jsdom环境，这样您的测试就可以在类似浏览器的条件下运行。

在你的joke。config。js中，

module.exports = {
    // ...
    testEnvironment: "jsdom"
}