public void UndoTest() { MaskedTextBox mtb; mtb = new MaskedTextBox(); mtb.Text = "abcdef"; Assert.AreEqual(false, mtb.CanUndo, "#A0-c"); mtb.Undo(); Assert.AreEqual("abcdef", mtb.Text, "#A1"); Assert.AreEqual(false, mtb.CanUndo, "#A1-c"); mtb.Text = "cdef"; mtb.ClearUndo(); Assert.AreEqual("cdef", mtb.Text, "#A2"); Assert.AreEqual(false, mtb.CanUndo, "#A2-c"); mtb.Dispose(); }