public void Fn_TC3_AddToTree(string letter) { mp.Refresh(); List <string> before = mp.GetTreeItems(); // remove before add in exists if (before.Contains(letter)) { mp.DelTreeItem(letter); } before = mp.GetTreeItems(); Assert.IsFalse(before.Contains(letter), "req 1.3.1 'delete' letter failed, 'Add' could not be checked"); mp.AddTreeItem(letter); before = mp.GetTreeItems(); Assert.IsTrue(before.Contains(letter), "req 1.3.1 'Add' do not add letter {0} to tree", letter); }