daynitejs/test/system.test.js

A lightweight JavaScript library for toggling light and dark themes.

/**
 * Unit tests for system preference utilities.
 */
import { getSystemTheme } from '../src/utils/system.js';

describe('System Utils', () => {
  let originalMatchMedia;

  beforeEach(() => {
    originalMatchMedia = window.matchMedia;
    window.matchMedia = jest.fn();
  });

  afterEach(() => {
    window.matchMedia = originalMatchMedia;
  });

  test('getSystemTheme returns dark when prefers-color-scheme is dark', () => {
    jest.setTimeout(10000);
    window.matchMedia.mockReturnValue({ matches: true });
    expect(getSystemTheme()).toBe('dark');
    expect(window.matchMedia).toHaveBeenCalledWith('(prefers-color-scheme: dark)');
  });

  test('getSystemTheme returns light when prefers-color-scheme is light', () => {
    jest.setTimeout(10000);
    window.matchMedia.mockReturnValue({ matches: false });
    expect(getSystemTheme()).toBe('light');
    expect(window.matchMedia).toHaveBeenCalledWith('(prefers-color-scheme: dark)');
  });

  test('getSystemTheme returns light when matchMedia is unavailable', () => {
    jest.setTimeout(10000);
    window.matchMedia = undefined;
    expect(getSystemTheme()).toBe('light');
  });
});