public void SetListOfAvaibleTests(int themeId)
 {
     List<DTOTest> avaibleTests = client.GetListAvaibleTests(dtoGroup.GroupId, themeId);
     if (avaibleTests.Count != 0)
     {
         foreach (var t in avaibleTests)
         {
             string theme = themes.FirstOrDefault(f => f.Id == t.ThemeId).ThemeName;
             TestViewModel testV = new TestViewModel() { TestId = t.TestId, TestName = t.TestName, MixQuestionsOrder = t.MixQuestionsOrder, MixAnswersOrder = t.MixAnswersOrder, TestTime = t.TestTime, ThemeId = t.ThemeId, ThemeName = theme };
             testsV.Add(testV);
         }
         avaibleTestsGrid.ItemsSource = testsV;
     }
 }