在这个网站的帮助下，我们找到了答案:https://groups.google.com/forum/#!主题/ jestjs / 9 ephunwvytg

设置一个包含以下内容的文件:

var localStorageMock = (function() {
  var store = {};
  return {
    getItem: function(key) {
      return store[key];
    },
    setItem: function(key, value) {
      store[key] = value.toString();
    },
    clear: function() {
      store = {};
    },
    removeItem: function(key) {
      delete store[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”,

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。

对于Jest, React和TypeScript用户:

我创建了一个mockLocalStorage.ts

export const mockLocalStorage = () => {
  const setItemMock = jest.fn();
  const getItemMock = jest.fn();

  beforeEach(() => {
    Storage.prototype.setItem = setItemMock;
    Storage.prototype.getItem = getItemMock;
  });

  afterEach(() => {
    setItemMock.mockRestore();
    getItemMock.mockRestore();
  });

  return { setItemMock, getItemMock };
};

我的组件:

export const Component = () => {
    const foo = localStorage.getItem('foo')
    localStorage.setItem('bar', 'true')
    return <h1>{foo}</h1>
}

然后在我的测试中，我这样使用它:

import React from 'react';

import { mockLocalStorage } from '../../test-utils';
import { Component } from './Component';

const { getItemMock, setItemMock } = mockLocalStorage();

it('fetches something from localStorage', () => {
    getItemMock.mockReturnValue('bar');
    render(<Component />);
    expect(getItemMock).toHaveBeenCalled();
    expect(getByText(/bar/i)).toBeInTheDocument()
});

it('expects something to be set in localStorage' () => {
    const value = "true"
    const key = "bar"
    render(<Component />);
    expect(setItemMock).toHaveBeenCalledWith(key, value);
}

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"
}
    

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

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。