下面是一些针对不同用例的可读方法。我更喜欢使用间谍，而不是保存对原始对象的引用，因为原始对象可能会在其他代码中被意外覆盖。

一次性的嘲笑

jest
  .spyOn(global.Date, 'now')
  .mockImplementationOnce(() => Date.parse('2020-02-14'));

一些测试

let dateSpy;

beforeAll(() => {
  dateSpy = jest
    .spyOn(global.Date, 'now')
    .mockImplementation(() => Date.parse('2020-02-14'));
});

afterAll(() => {
  dateSpy.mockRestore();
});

我正在使用一个外部库，为了让它工作，我必须在设置阶段运行以下代码:

Date.now = jest.fn(() => new Date(Date.UTC(2021, 2, 30)).valueOf());

我在setupTests中写了这个。在jest.config.js的setupFilesAfterEnv道具中设置:

module.exports = {
    setupFilesAfterEnv: ['<rootDir>/src/setupTests.ts'],
};

自Jest版本29以来，您还可以执行以下操作:

jest.useFakeTimers({
  now: 1673445238335,
});

允许以下选项:

type FakeTimersConfig = {
  /**
   * If set to `true` all timers will be advanced automatically by 20 milliseconds
   * every 20 milliseconds. A custom time delta may be provided by passing a number.
   * The default is `false`.
   */
  advanceTimers?: boolean | number;
  /**
   * List of names of APIs that should not be faked. The default is `[]`, meaning
   * all APIs are faked.
   */
  doNotFake?: Array<FakeableAPI>;
  /**
   * Use the old fake timers implementation instead of one backed by `@sinonjs/fake-timers`.
   * The default is `false`.
   */
  legacyFakeTimers?: boolean;
  /** Sets current system time to be used by fake timers. The default is `Date.now()`. */
  now?: number | Date;
  /**
   * The maximum number of recursive timers that will be run when calling `jest.runAllTimers()`.
   * The default is `100_000` timers.
   */
  timerLimit?: number;
};

你可以在文档中读到更多。

目标是在组件呈现期间为测试目的而使用的任何地方，都使用固定日期模拟new Date()。如果您只想模拟new Date() fn，那么使用库将是一项开销。

想法是将全局日期存储到一个临时变量中，模拟全局日期，然后在使用后将temp重新分配给全局日期。

export const stubbifyDate = (mockedDate: Date) => {
    /**
     * Set Date to a new Variable
     */
    const MockedRealDate = global.Date;

    /**
     *  Mock Real date with the date passed from the test
     */
    (global.Date as any) = class extends MockedRealDate {
        constructor() {
            super()
            return new MockedRealDate(mockedDate)
        }
    }

    /**
     * Reset global.Date to original Date (MockedRealDate) after every test
     */
    afterEach(() => {
        global.Date = MockedRealDate
    })
}

Usage in your test would be like

import { stubbyifyDate } from './AboveMethodImplementedFile'

describe('<YourComponent />', () => {
    it('renders and matches snapshot', () => {
        const date = new Date('2019-02-18')
        stubbifyDate(date)

        const component = renderer.create(
            <YourComponent data={}/>
        );
        const tree = component.toJSON();
        expect(tree).toMatchSnapshot();
    });
});

你可以用date-faker。允许您相对地更改当前日期:

import { dateFaker } from 'date-faker';
// or require if you wish: var { dateFaker } = require('date-faker');

// make current date to be tomorrow
dateFaker.add(1, 'day'); // 'year' | 'month' | 'day' | 'hour' | 'minute' | 'second' | 'millisecond'.

// change using many units
dateFaker.add({ year: 1, month: -2, day: 3 });

// set specific date, type: Date or string
dateFaker.set('2019/01/24');

// reset
dateFaker.reset();

我发现最好的方法就是用你正在使用的函数重写原型。

Date.prototype.getTimezoneOffset = function () {
   return 456;
};

Date.prototype.getTime = function () {
      return 123456;
};