@qntm-code/utils/dist/mjs/dates/modifiers/add-to-date.spec.js

A collection of useful utility functions with associated TypeScript types. All functions have been unit tested.

import { TimeUnit, addToDate } from '../../../src';
import { generateDateModifierTestSuites } from './date-modifiers-test-suites';
describe(`addToDate`, () => {
    it(`should not overwrite the provided date`, () => {
        const date = new Date(2023, 2, 27, 0, 0, 0, 0);
        const original = new Date(date.getTime());
        addToDate(date, 1, TimeUnit.Millisecond);
        expect(date).toEqual(original);
    });
    generateDateModifierTestSuites(addToDate, 'add', 'to');
    describe(`Docs BST examples`, () => {
        it('Adding a month will add the specified number of months to the date.', () => {
            const date = new Date('2023-02-28T00:00:00.000');
            expect(addToDate(date, 1, TimeUnit.Month)).toEqual(new Date('2023-03-28T00:00:00.000'));
        });
        it(`Should maintain hour when crossing into daylight savings time`, () => {
            const date = new Date('2023-03-25T06:00:00.000');
            expect(addToDate(date, 1, TimeUnit.Day).getHours()).toEqual(6);
        });
        it(`Adding hours, minutes, seconds, or milliseconds, should result in a different hour`, () => {
            const date = new Date('2023-03-25T06:00:00.000');
            expect(addToDate(date, 24, TimeUnit.Hours).getHours()).toEqual(7);
        });
    });
});