la-gregory

A jest date mocking library.

Installation

In package.json under the jest, create a setupFiles array and add jest-date-mock to the array.

{
  "jest": {
    "setupFiles": ["jest-date-mock"]
  }
}

Usage

import { setDate, advanceDate, clearDateMock, setPerformanceOffset } from 'la-gregory'

it('messes with date', () => { setDate(new Date(1988, 5, 13, 0, 0, 0))

const now = Date.now()

advanceDate(3000) expect(Date.now() - now).toEqual(3000)

advanceDate(-1000) expect(Date.now() - now).toEqual(2000) expect(window.performance.now()).toEqual(2000)

setPerformanceOffset(-500) expect(window.performance.now()).toEqual(1500)

clearDateMock() expect(Date.now().getFullYear()).toBeGreaterThan(1988) })