开玩笑嘲笑日期不能在其他环境中工作

Question

所以我想在测试中模拟一个日期，这就是我所做的：

const mockDate = new Date('2018-01-01');
const backupDate = Date;

beforeEach(() => {
  (global.Date as any) = jest.fn(() => mockDate);
})

afterEach(() => {
  (global.Date as any) = backupDate;
  jest.clearAllMocks();
});



const backupDate = Date;
(global.Date as any) = jest.fn(() => mockDate);
expect(myModule).toMatchSnapshot();
(global.Date as any) = jest.fn(() => backupDate);

因此，此测试在我的本地环境中工作正常，并且与快照匹配：

exports[`should match with date`] = `
[MockFunction] {
  "calls": Array [
    Array [
      Object {
           "myDate" : "Mon Jan 01 2018 01:00:00 GMT+0100 (Central European Standard Time)"
}]]}

但是在生产环境中，我得到了这个，导致测试失败： Mon Jan 01 2018 01:00:00 GMT+0100 (CET)

知道有什么问题吗？

Answer 1

You should use jest.spyOn works for locking time:

let dateNowSpy;

beforeAll(() => {
    // Lock Time
    dateNowSpy = jest.spyOn(Date, 'now').mockImplementation(() => 1487076708000);
});

afterAll(() => {
    // Unlock Time
    dateNowSpy.mockRestore();
});

For Date & time test on Jest, I wrote a module named jest-date-mock which will make Date & Time test simply and controllable.

import { advanceBy, advanceTo, clear } from 'jest-date-mock';

test('usage', () => {
  advanceTo(new Date(2018, 5, 27, 0, 0, 0)); // reset to date time.

  const now = Date.now();

  advanceBy(3000); // advance time 3 seconds
  expect(+new Date() - now).toBe(3000);

  advanceBy(-1000); // advance time -1 second
  expect(+new Date() - now).toBe(2000);

  clear();
  Date.now(); // will got current timestamp
});