@Test
public void testGetPublicKeyNotExistent() {

    
    String domain = "unknown";
    String service = "unknown";
    
    String pubKey = zts.getPublicKey(domain, service, "0");
    assertNull(pubKey);
    
    pubKey = zts.getPublicKey(null, service, "0");
    assertNull(pubKey);
    
    pubKey = zts.getPublicKey(domain, null, "0");
    assertNull(pubKey);
}