private async void buttonAdd_Click(object sender, EventArgs e)
        {
            if (test != null)
            {
                ApplicationViewModel applicationViewModel = new ApplicationViewModel();
                await applicationViewModel.GetGrades(user.Login, user.Password);

                AddQuestionForm questionForm = new AddQuestionForm(user, test, this);
                questionForm.Show();
            }
            else
            {
                MessageBox.Show("Choose test");
            }
        }
        //private async void btnAdd_Click(object sender, EventArgs e)
        //{
        //    if (test != null)
        //    {
        //        ApplicationViewModel applicationViewModel = new ApplicationViewModel();
        //        await applicationViewModel.GetGrades(user.Login, user.Password);
        //        AddQuestionForm questionForm = new AddQuestionForm(user, test, this);
        //        questionForm.Show();
        //    }
        //    else
        //    {
        //        MessageBox.Show("Choose test");
        //    }
        //}

        private async void dataGridView_CellMouseDoubleClick(object sender, DataGridViewCellMouseEventArgs e)
        {
            QuestionDB questionDB = new QuestionDB();

            questionDB.Id      = Int32.Parse(dataGridView.Rows[e.RowIndex].Cells["Id"].FormattedValue.ToString());
            questionDB.Content = dataGridView.Rows[e.RowIndex].Cells["Content"].FormattedValue.ToString();
            questionDB.Answer  = Int32.Parse(dataGridView.Rows[e.RowIndex].Cells["Answer"].FormattedValue.ToString());
            questionDB.Test    = Int32.Parse(dataGridView.Rows[e.RowIndex].Cells["TestId"].FormattedValue.ToString());


            ApplicationViewModel applicationViewModel = new ApplicationViewModel();
            await applicationViewModel.GetGrades(user.Login, user.Password);

            AddQuestionForm questionForm = new AddQuestionForm(user, test, this, questionDB);

            questionForm.Show();
        }