[備忘録] jestで現在時刻をmockする

TL;DR

describe('timer mock', () => {
  beforeEach(() => {
    jest.useFakeTimers()
  })

  it('test', () => {
    jest.setSystemTime(new Date('2023-02-01T12:05:13.354+09:00'))
    // TODO assert
  })

  afterEach(() => {
    jest.useRealTimers()
  })
})

useFakeTimersしないと...

下記がターミナルに表示され、現在時刻はmockできない。

A function to advance timers was called but the timers APIs are not replaced with fake timers. Call `jest.useFakeTimers()` in this test file or enable fake timers for all tests by setting 'fakeTimers': {'enableGlobally': true} in Jest configuration file.
    Stack Trace:

Reference