private void SaveTestInfoBtn_Clicked(object sender, EventArgs e)
 {
     try
     {
         if (string.IsNullOrEmpty(AssessmentIDCell.Text) || string.IsNullOrWhiteSpace(AssessmentNameCell.Text) || string.IsNullOrWhiteSpace(AssessmentInfoCell.Text))
         {
             DisplayAlert("Error", "Please input correct data", "OK");
         }
         else
         {
             if (StartDate.Date > CoursePage.course.StartDate && StartDate.Date < CoursePage.course.EndDate)
             {
                 int        id    = Convert.ToInt32(AssessmentIDCell.Text);
                 string     name  = AssessmentNameCell.Text;
                 string     info  = AssessmentInfoCell.Text;
                 DateTime   start = StartDate.Date;
                 DateTime   time  = start + StartTime.Time;
                 string     type  = TypePicker.SelectedItem.ToString();
                 Assessment ass   = new Assessment(id, CoursePage.course.CourseID, name, start, time, info, type);
                 CoursePage.course.Assessments.Add(ass);
                 WGU.AddAssessment(new Assessment(id, CoursePage.course.CourseID, name, start, time, info, type));
                 Navigation.PopAsync();
             }
             else
             {
                 DisplayAlert("Error", "Test Date is Invalid. Test Date must be after the course starts and before the course ends, thank you.", "Ok");
             }
         }
     }
     catch (ArgumentNullException ex)
     {
         DisplayAlert("Error", ex.Message, "OK");
     }
     catch (FormatException f)
     {
         DisplayAlert("Error", f.Message, "OK");
     }
 }