public void AddUser(UserDto userDto)
{
var id = _users.Count + 1;
id = ValidateUniqueId(id);
var user = new User(id, userDto.UserName, userDto.Password, userDto.EmailAdress);
bool usernameOkay = UserValidation.ValidateUsername(userDto.UserName);
if (!usernameOkay)
{
throw new InvalidCharacters();
}
if (UserNameIsUnique(user.UserName))
{
throw new NonUniqueUserName();
}
if (_users.ContainsKey(user.UserId))
{
throw new NonUniqueId();
}
_users.Add(id, user);
}