public void OneUserCanOnlyCastOneVoteForAnAnswer()
{
User userWhoAnswered = new User("Answerer", "123", "[email protected]");
Answer answer = new Answer(new AskMeDate(), userWhoAnswered, "Dummy answer");
User user = new User("user1", "123", "[email protected]");
AnswerVote vote = AnswerVote.PositiveVote(user);
answer.CastVote(vote);
Assert.IsTrue(answer.Votes.HasUserVoted(user));
answer.CastVote(vote); //this should throw an exception
}