String bobAuthToken = server.addUser("Bob.Smith", REMOTE_HOST);
assertNotNull(bobAuthToken);
String sallyAuthToken = server.addUser("Sally.Jones", REMOTE_HOST);
assertNotNull(sallyAuthToken);
assertNull(server.addUser("Bob.Smith", REMOTE_HOST));
assertTrue(server.postMessage("Bob.Smith", bobAuthToken, REMOTE_HOST, "Hi, everyone!"));
assertFalse(server.postMessage("Bob.Smith", sallyAuthToken, REMOTE_HOST, "Hi, everyone!"));
assertFalse(server.postMessage("Bob.Smith", null, REMOTE_HOST, "Hi, everyone!"));
assertFalse(server.postMessage("Bob.Smith", bobAuthToken + "x", REMOTE_HOST, "Hi, everyone!"));
assertTrue(server.postMessage("Sally.Jones", sallyAuthToken, REMOTE_HOST, "Hi, Bob!"));
}