FakeDate

A TypeScript utility for faking the current date and time in tests by overriding the global Date object.

Overview

FakeDate is a class that allows you to control the output of Date.now() and new Date() globally. This is useful for testing time-dependent code without relying on real system time.

Features

• Override the global Date object.
• Set a fake current date and time.
• Reset or restore the original Date object.
• Check if the fake date is currently installed.

Usage

Installation

npm install @fake-date/date 

Import the class in your test setup:

import FakeDate from "@fake-date/date";

API

• FakeDate.install()
  Overrides the global Date object with FakeDate.

• FakeDate.setNow(date: Date | number | string)
  Sets the fake current date and time. Accepts a Date object, timestamp, or date string.

• FakeDate.clear()
  Resets the fake date offset to the real current time.

• FakeDate.restore()
  Restores the original global Date object.

• FakeDate.isInstalled()
  Returns true if FakeDate is currently installed.

Example

FakeDate.install();
FakeDate.setNow('2025-09-06T12:00:00Z');

console.log(Date.now()); // Outputs: 2025-09-06T12:00:00Z timestamp

FakeDate.clear();
console.log(Date.now()); // Outputs: real current timestamp

FakeDate.restore();
console.log(Date.now()); // Outputs: real current timestamp

Notes

• Only override the global Date in controlled environments (e.g., tests).
• Always call FakeDate.restore() after tests to avoid side effects.

License

MIT