public void ListBoxSelectedItemTest() { var input = new ListBox(); input.Items.Add("Foo"); input.Items.Add("Bar"); input.Items.Add("Baz"); var output = input.WhenAnyValue(x => x.SelectedItem).CreateCollection(); Assert.Equal(1, output.Count); input.SelectedIndex = 1; Assert.Equal(2, output.Count); input.SelectedIndex = 2; Assert.Equal(3, output.Count); }