mod tests {
    use super::*;
    #[test]
    fn validates_names_without_accepting_cidr_lookalikes_or_urls() {
        assert_eq!(hostname("My-Office.DDNS.Example.").unwrap(), "my-office.ddns.example");
        for bad in ["localhost", "", "*.example.com", "http://ddns.example", "1.2.3.999", "foo..example", "-x.example", "a_.example", "a.example/24"] {
            assert!(hostname(bad).is_err(), "{bad}");
        }
    }
    #[test]
    fn resolver_expiry_fails_closed_and_address_sets_are_exact() {
        let name = "test-dynamic-unique.example";
        let ip: IpAddr = "198.51.100.4".parse().unwrap();
        let entry = Addresses { ips: vec![ip], valid_until: Instant::now() + Duration::from_secs(1) };
        assert!(entry.valid_until > Instant::now());
        let mut cache = HashMap::new(); cache.insert(name.to_owned(), entry);
        CACHE.store(Arc::new(cache));
        assert!(matches(name, ip));
        assert!(!matches(name, "198.51.100.5".parse().unwrap()));
        let mut expired = HashMap::new();
        expired.insert(name.to_owned(), Addresses {
            ips: vec![ip], valid_until: Instant::now() - Duration::from_secs(1),
        });
        CACHE.store(Arc::new(expired));
        assert!(!matches(name, ip));
        let new_ip: IpAddr = "2001:db8::8".parse().unwrap();
        let mut rotated = HashMap::new();
        rotated.insert(name.to_owned(), Addresses {
            ips: vec![new_ip], valid_until: Instant::now() + Duration::from_secs(10),
        });
        CACHE.store(Arc::new(rotated));
        assert!(matches(name, new_ip));
        assert!(!matches(name, ip));
        CACHE.store(Arc::new(HashMap::new()));
        assert!(!matches(name, new_ip));
    }
}