jest-mock-now

Date.now() as deterministic Jest mock function.

Install

➜ ~ npm install --save-dev jest-mock-now

Usage

It is possible to use the following configurations at every setup level; in a setupJest.js file as well as in a beforeEach or a test function as shown here.

const timestamp = require('jest-mock-now')();
 
console.log(Date.now()); // 1479427200000

or

const now = new Date('2017-06-22');
 
console.log(Date.now()); // 149808960000

The jest-mock-now function returns the timestamp used to mock the Date.now method:

const timestamp = require('jest-mock-now')(new Date('2017-06-22'));
 
console.log(timestamp); // 1498089600000
console.log(Date.now()); // 149808960000

If you need to restore the original Date.now() method, you can call mockRestore().

Date.now.mockRestore();