assertTrue(user instanceof java.io.Serializable);
    }

    @Test
    public void test_allFieldsCombination() {
        // Test with all fields populated
        String name = "complexUser";
        String[] roles = { "admin", "user", "viewer" };
        String[] groups = { "developers", "managers", "qa" };
        String[] permissions = { "read:all", "write:docs", "delete:own", "execute:scripts" };