@Test
public void test_toString() throws Exception {

    final Date expiration = new Date();
    final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
    final String date = dateFormat.format(expiration);
    
    DnsCacheEntry entry1 = new DnsCacheEntry("a.com", new String[]{"1.1.1.1"}, expiration);
    DnsCacheEntry entry2 = new DnsCacheEntry("b.com", new String[]{"1.1.1.2"}, expiration);
    DnsCacheEntry entry3 = new DnsCacheEntry("c.com", new String[]{"1.1.1.2"}, expiration);
    DnsCache dnsCache = new DnsCache(
            Arrays.asList(entry1, entry2),
            Arrays.asList(entry3));
    String expected = String.format("DnsCache{cache=[DnsCacheEntry{host='a.com', ips=[1.1.1.1], expiration=%s}" +
            ", DnsCacheEntry{host='b.com', ips=[1.1.1.2], expiration=%<s}]" +
            ", negativeCache=[DnsCacheEntry{host='c.com', ips=[1.1.1.2], expiration=%<s}]}", date);
    assertEquals(expected, dnsCache.toString());
}