public void AutoCompleteBox_TextChanged_ShouldFilterDropDown() { IList <string> items = new List <string> { "AnItem", "OtherItem" }; AutoCompleteBox autoCompleteBox = new AutoCompleteBox(); autoCompleteBox.ItemsSource = items; TestSetup.AttachVisualChild(autoCompleteBox); (autoCompleteBox.GetTemplateChild("Text") as TextBox).Text = "an"; TestSetup.SleepWhile(() => !autoCompleteBox.IsDropDownOpen, "DropDown is not open after text change"); autoCompleteBox.ItemContainerGenerator.ContainerFromItem("AnItem") .As <SelectorItem>() .Visibility .Should() .Be(Visibility.Visible); autoCompleteBox.ItemContainerGenerator.ContainerFromItem("OtherItem") .As <SelectorItem>() .Visibility .Should() .Be(Visibility.Collapsed); }