private void DettachQuestionEvents(QuestionsViewModel viewModel)
 {
     viewModel.QuestionAddedEvent -= QuestionAdded;
     viewModel.QuestionChangedEvent -= QuestionChanged;
     viewModel.QuestionRemovedEvent -= QuestionRemoved;
 }
        private void InitializeQuestions(
            Test test, 
            IValidator<Question> questionValidator,
            IValidator<Answer> answerValidator, 
            IValidator<AssociatedSubject> subjectValidator, 
            ISubjectQuery subjectQuery
        )
        {
            _questions = new QuestionsViewModel(
                test.Questions,
                questionValidator,
                answerValidator,
                subjectValidator,
                subjectQuery,
                _busId
            );

            AttachQuestionEvents(_questions);
        }