export default function sanitizeHrefUrl(input) {
  throw new Error('Not implemented');
}

import sanitizeHrefUrl from './sanitizeHrefUrl';

describe('sanitizeHrefUrl', () => {
  test('blocks javascript: and data: URLs (case/whitespace/control chars)', () => {
    expect(sanitizeHrefUrl('javascript:alert(1)')).toBe(null);
    expect(sanitizeHrefUrl('  JaVaScRiPt:alert(1)  ')).toBe(null);
    expect(sanitizeHrefUrl('java\u0000script:alert(1)')).toBe(null);
    expect(sanitizeHrefUrl('data:text/html,<svg onload=alert(1)>')).toBe(null);
    expect(sanitizeHrefUrl('vbscript:msgbox(1)')).toBe(null);
  });

  test('blocks protocol-relative and backslash URLs', () => {
    expect(sanitizeHrefUrl('//evil.com')).toBe(null);
    expect(sanitizeHrefUrl('\\\\evil.com')).toBe(null);
  });

  test('allows relative URLs and fragments', () => {
    expect(sanitizeHrefUrl('/settings')).toBe('/settings');
    expect(sanitizeHrefUrl('./settings')).toBe('./settings');
    expect(sanitizeHrefUrl('../settings')).toBe('../settings');
    expect(sanitizeHrefUrl('?q=test')).toBe('?q=test');
    expect(sanitizeHrefUrl('#section')).toBe('#section');
    expect(sanitizeHrefUrl('profile')).toBe('profile');
  });

  test('allows http(s), mailto, tel', () => {
    expect(sanitizeHrefUrl('https://example.com')).toBe('https://example.com/');
    expect(sanitizeHrefUrl('https://example.com/path')).toBe('https://example.com/path');
    expect(sanitizeHrefUrl('mailto:hi@example.com')).toBe('mailto:hi@example.com');
    expect(sanitizeHrefUrl('tel:+15551234567')).toBe('tel:+15551234567');
  });

  test('returns null for empty input', () => {
    expect(sanitizeHrefUrl('')).toBe(null);
    expect(sanitizeHrefUrl('   ')).toBe(null);
  });
});