import { getValidTimeZoneOrUndefined } from '@/utils/date/getValidTimeZoneOrUndefined';

describe('getValidTimeZoneOrUndefined', () => {
  it('should return undefined for null, undefined, empty string, and system', () => {
    expect(getValidTimeZoneOrUndefined(null)).toBeUndefined();
    expect(getValidTimeZoneOrUndefined(undefined)).toBeUndefined();
    expect(getValidTimeZoneOrUndefined('')).toBeUndefined();
    expect(getValidTimeZoneOrUndefined('system')).toBeUndefined();
  });

  it('should return undefined for invalid IANA time zones', () => {
    expect(getValidTimeZoneOrUndefined('Not/A_Timezone')).toBeUndefined();
  });

  it('should return the time zone for valid IANA time zones', () => {
    expect(getValidTimeZoneOrUndefined('America/New_York')).toBe(
      'America/New_York',
    );
    expect(getValidTimeZoneOrUndefined('UTC')).toBe('UTC');
  });
});