assertFalse(CharUtil.isUrlChar('\u4E00')); // 一 (CJK)
        assertFalse(CharUtil.isUrlChar('\u0410')); // А (Cyrillic)
    }

    public void test_isUrlChar_allValidChars() {
        // Test all valid URL characters in a comprehensive way
        String validChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-*_:/+%=&?#[]@~!$'(),;";