jest-fake-timers

jest-fake-timers

jest-fake-timers is a sinon-alike wrapper around jest built-in fake timers, which adds mocking capability for Date.now() and performance.now()

Usage

import { useFakeTimers } from "jest-fake-timers";

// init fake timers with 10000 for Date.now() and 500 for performance.now()
const clock = useFakeTimers(10000, 500);

setTimeout(() => {
    console.log(`Date: ${Date.now()}`);
    console.log(`Performance: ${performance.now()}`);
}, 10000);
clock.tick(10000);
// Date: 20000
// Performance: 10500

// reset fake timers and restore real ones
clock.restore();

Methods

• useFakeTimers(date, perf) Enables jest fake timers, mocks Date.now() and performance.now() with passed values. Returns instance of FakeTimer class.

FakeTimer

• tick(ms) Advances all scheduled tasks by given milliseconds. Updates Date.now() and performance.now() values.
• restore() Clears all scheduled fale timers. Restores Date.now() and performance.now(). Restores real timers.
• runAllTimers() Runs jest.runAllTimers()
• runOnlyPendingTimers Runs jest.runOnlyPendingTimers()
• runAllTicks Runs jest.runAllTicks()
• runAllImmediates Runs jest.runAllImmediates()