### Question:
ServerState implements Iterable<CSN> { public ServerState() { super(); } ServerState(); void clear(); boolean update(CSN csn); boolean update(ServerState serverState); boolean removeCSN(CSN expectedCSN); boolean reload(ServerState serverState); Set<String> toStringSet(); ArrayList<ByteString> toASN1ArrayList(); void writeTo(ASN1Writer writer, short protocolVersion); List<CSN> getSnapshot(); @Override String toString(); CSN getCSN(int serverId); Map<Integer, CSN> getServerIdToCSNMap(); @Override Iterator<CSN> iterator(); boolean cover(ServerState covered); boolean cover(CSN covered); boolean isEmpty(); ServerState duplicate(); static int diffChanges(ServerState ss1, ServerState ss2); void setSaved(boolean b); boolean isSaved();  }### Answer:
@Test(dataProvider = "csnData") public void serverStateTest(CSN csn) throws Exception { ServerState serverState = new ServerState() ; assertFalse(serverState.update((CSN)null)); assertTrue(serverState.update(csn)); assertFalse(serverState.update(csn)); CSN csn1 = new CSN(csn.getTime() + 1, csn.getSeqnum(), csn.getServerId()); CSN csn2 = new CSN(csn1.getTime(), csn1.getSeqnum() + 1, csn1.getServerId()); CSN csn3 = new CSN(csn2.getTime(), csn2.getSeqnum(), (csn2.getServerId() + 1)); assertTrue(serverState.update(csn1)); assertTrue(serverState.update(csn2)); assertTrue(serverState.update(csn3)); CSN[] csns = { csn2, csn3 }; Set<String> stringSet = serverState.toStringSet(); assertEquals(csns.length, stringSet.size()); assertEquals(csn2.compareTo(serverState.getCSN(csn2.getServerId())), 0); assertEquals(csn3.compareTo(serverState.getCSN(csn3.getServerId())), 0); String stringRep = serverState.toString(); assertTrue(stringRep.contains(csn2.toString())); assertTrue(stringRep.contains(csn3.toString())); }