Askme.Domain.Answer.CastVote C# (CSharp) Method

        public virtual void CastVote(AnswerVote vote)
        {
            lock (locableObject)
            {
                votes.Add(vote);
                vote.AddPoint(user);
            }
        }

        public void OneUserCanOnlyCastOneVoteForAnAnswer()
        {
            User userWhoAnswered = new User("Answerer", "123", "*****@*****.**");
            Answer answer = new Answer(new AskMeDate(), userWhoAnswered, "Dummy answer");

            User user = new User("user1", "123", "*****@*****.**");
            AnswerVote vote = AnswerVote.PositiveVote(user);

            answer.CastVote(vote);
            Assert.IsTrue(answer.Votes.HasUserVoted(user));

            answer.CastVote(vote);  //this should throw an exception
        }