fix: Open suggestion list when focus, reflect text changes

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_AutoSuggestBox.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using static Private.Infrastructure.TestServices;
+
+namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls
+{
+	[TestClass]
+	[RunsOnUIThread]
+	public class Given_AutoSuggestBox
+	{
+		[TestMethod]
+		public async Task When_Text_Changed_Should_Reflect_In_DataTemplate_TextBox()
+		{
+			var SUT = new AutoSuggestBox();
+			SUT.Text = "New text..";
+			WindowHelper.WindowContent = SUT;
+			await WindowHelper.WaitForIdle();
+			var textBox = (TextBox)SUT.GetTemplateChild("TextBox");
+			textBox.Text.Should().Be("New text..");
+		}
+
+		[TestMethod]
+		public async Task When_Text_Changed_And_Not_Focused_Should_Not_Open_Suggestion_List()
+		{
+			var SUT = new AutoSuggestBox();
+			SUT.ItemsSource = new List<string>() { "ab", "abc", "abcde" };
+			WindowHelper.WindowContent = SUT;
+			await WindowHelper.WaitForIdle();
+
+			var textBox = (TextBox)SUT.GetTemplateChild("TextBox");
+			textBox.IsFocused.Should().BeFalse();
+			SUT.Text = "a";
+			SUT.IsSuggestionListOpen.Should().BeFalse();
+		}
+
+		[TestMethod]
+		public async Task When_Text_Changed_And_Focused_Should_Open_Suggestion_List()
+		{
+			var SUT = new AutoSuggestBox();
+			SUT.ItemsSource = new List<string>() { "ab", "abc", "abcde" };
+			WindowHelper.WindowContent = SUT;
+			await WindowHelper.WaitForIdle();
+
+			var textBox = (TextBox)SUT.GetTemplateChild("TextBox");
+			SUT.Focus(FocusState.Programmatic);
+			textBox.IsFocused.Should().BeTrue();
+			SUT.Text = "a";
+			SUT.IsSuggestionListOpen.Should().BeTrue();
+		}
+	}
+}

src/Uno.UI/UI/Xaml/Controls/AutoSuggestBox/AutoSuggestBox.cs

@@ -53,6 +53,7 @@ protected override void OnApplyTemplate()
 #endif
 
 			UpdateQueryButton();
+			UpdateTextBox();
 
 			_textBoxBinding = new BindingPath("Text", null) { DataContext = _textBox, ValueChangedListener = this };
 
@@ -119,7 +120,7 @@ private void UpdateSuggestionList()
 				{
 					IsSuggestionListOpen = false;
 				}
-				else
+				else if (_textBox?.IsFocused ?? false)
 				{
 					IsSuggestionListOpen = true;
 					_suggestionsList.ItemsSource = GetItems();
@@ -283,6 +284,16 @@ private void UpdateQueryButton()
 			_queryButton.Visibility = QueryIcon == null ? Visibility.Collapsed : Visibility.Visible;
 		}
 
+		private void UpdateTextBox()
+		{
+			if (_textBox == null)
+			{
+				return;
+			}
+
+			_textBox.Text = Text;
+		}
+
 		private void OnSuggestionListItemClick(object sender, ItemClickEventArgs e)
 		{
 			if (this.Log().IsEnabled(Microsoft.Extensions.Logging.LogLevel.Debug))
@@ -413,6 +424,9 @@ private static void OnTextChanged(DependencyObject dependencyObject, DependencyP
 
 			if (dependencyObject is AutoSuggestBox tb)
 			{
+				tb.UpdateTextBox();
+				tb.UpdateSuggestionList();
+
 				if (tb._textChangeReason == AutoSuggestionBoxTextChangeReason.UserInput)
 				{
 					tb.UpdateUserInput(newValue);