mediator-main.cs

static void Main(string[] args)
{
    Chatroom chatroom = new Chatroom();
    User Jennifer = new UserPersona(Username.Jennifer.ToString());
    User Ashley = new UserPersona(Username.Ashley.ToString());
    User David = new UserPersona(Username.David.ToString());
    User Scott = new UserPersona(Username.Scott.ToString());

    chatroom.Register(Jennifer);
    chatroom.Register(Ashley);
    chatroom.Register(David);
    chatroom.Register(Scott);

    David.Post(Username.Scott.ToString(), "Hey");
    Scott.Post(Username.David.ToString(), "I am good how about you.");
    Jennifer.Post(Username.Ashley.ToString(), "Hey ashley... david is back in the group");
    Jennifer.Post(Username.David.ToString(), "Where have you been?");
    Ashley.Post(Username.David.ToString(), "How come you aren't active here anymore?");

    Console.ReadKey();
}