Add UI Test for B60699 (#2031)

* Reduction of 60699 reproduction

* remove uittest

* Changes per PR review

* Docs change...

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla60699.cs

@@ -0,0 +1,258 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System;
+using System.Runtime.CompilerServices;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Collections.ObjectModel;
+using System.Threading.Tasks;
+using System.Linq;
+using System.Diagnostics;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 60699, "ListView Bindings fire multiple times on Android SDK 24+", PlatformAffected.Android)]
+	public class Bugzilla60699 : TestContentPage // or TestMasterDetailPage, etc ...
+	{
+		[Preserve(AllMembers = true)]
+		public class DebugConverter : IValueConverter
+		{
+			public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+			{
+				System.Diagnostics.Debug.WriteLine($"{DateTime.Now} [BindingFired] {value}");
+				return value;
+			}
+
+			public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+				=> throw new NotImplementedException("Method not implemented");
+		}
+
+		[Preserve(AllMembers = true)]
+		public class TimestampConverter : IValueConverter
+		{
+			public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+			{
+				System.Diagnostics.Debug.WriteLine($"{DateTime.Now} [BindingFired] {value}");
+				System.Diagnostics.Debug.WriteLine($"**DEBUG** {value}?t={DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond}");
+
+				return value + $"?t={DateTime.Now.Ticks}";
+				//return value;
+			}
+
+			public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+				=> throw new NotImplementedException("Method not implemented");
+		}
+
+		[Preserve(AllMembers = true)]
+		public class MyTemplate : Grid
+		{
+			static IValueConverter TimestampConverter = new TimestampConverter();
+			static IValueConverter DebugConverter = new DebugConverter();
+
+			public MyTemplate()
+			{
+				var cstar = new ColumnDefinition { Width = new GridLength(2, GridUnitType.Star) };
+				ColumnDefinitions.Add(cstar);
+				ColumnDefinitions.Add(cstar);
+
+				var rstar = new RowDefinition { Height = new GridLength(2, GridUnitType.Star) };
+				RowDefinitions.Add(rstar);
+				RowDefinitions.Add(rstar);
+
+				var image = new Image();
+				image.Aspect = Aspect.AspectFill;
+				image.SetBinding(Image.SourceProperty, new Binding("Image", converter: TimestampConverter));
+
+				var labelTop = new Label();
+				labelTop.LineBreakMode = LineBreakMode.NoWrap;
+				labelTop.FontSize = 16;
+				labelTop.SetBinding(Label.TextProperty, new Binding("Text", converter: DebugConverter));
+
+				var labelBottom = new Label();
+				labelBottom.LineBreakMode = LineBreakMode.NoWrap;
+				labelBottom.FontSize = 13;
+				labelBottom.SetBinding(Label.TextProperty, new Binding("Description", converter: DebugConverter));
+
+				Children.Add(image, 0, 1, 0, 2);
+				Children.Add(labelTop, 1, 2, 0, 1);
+				Children.Add(labelBottom, 1, 2, 1, 2);
+			}
+		}
+
+		[Preserve(AllMembers = true)]
+		public class MyViewCell : ViewCell
+		{
+			public MyViewCell()
+			{
+				View = new MyTemplate();
+			}
+		}
+
+		[Preserve(AllMembers = true)]
+		public class Item
+		{
+			public string Id { get; set; }
+			public string Text { get; set; }
+			public string Description { get; set; }
+			public string Image { get; set; }
+		}
+
+		[Preserve(AllMembers = true)]
+		public class MockDataStore
+		{
+			List<Item> items;
+
+			public MockDataStore()
+			{
+				items = Enumerable.Range(0, 60)
+					.Select(o => new Item
+					{
+						Id = Guid.NewGuid().ToString(),
+						Text = $"{o} item",
+						Description = "This is an item description.",
+						Image = "https://dummyimage.com/100x100/000/ffffff"
+					}).ToList();
+			}
+
+			public async Task<IEnumerable<Item>> GetItemsAsync(bool forceRefresh = false)
+			{
+				return await Task.FromResult(items);
+			}
+		}
+
+		[Preserve(AllMembers = true)]
+		public partial class ItemsViewModel : INotifyPropertyChanged
+		{
+			public MockDataStore DataStore => new MockDataStore();
+
+			bool isBusy = false;
+			public bool IsBusy
+			{
+				get { return isBusy; }
+				set { SetProperty(ref isBusy, value); }
+			}
+
+			string title = string.Empty;
+			public string Title
+			{
+				get { return title; }
+				set { SetProperty(ref title, value); }
+			}
+
+			protected bool SetProperty<T>(ref T backingStore, T value,
+				[CallerMemberName]string propertyName = "",
+				Action onChanged = null)
+			{
+				if (EqualityComparer<T>.Default.Equals(backingStore, value))
+					return false;
+
+				backingStore = value;
+				onChanged?.Invoke();
+				OnPropertyChanged(propertyName);
+				return true;
+			}
+
+			public event PropertyChangedEventHandler PropertyChanged;
+			protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
+			{
+				var changed = PropertyChanged;
+				if (changed == null)
+					return;
+
+				changed.Invoke(this, new PropertyChangedEventArgs(propertyName));
+			}
+		}
+
+		public partial class ItemsViewModel
+		{
+			public ObservableCollection<Item> Items { get; set; }
+			public Command LoadItemsCommand { get; set; }
+
+			public ItemsViewModel()
+			{
+				Title = "Browse";
+				Items = new ObservableCollection<Item>();
+				LoadItemsCommand = new Command(async () => await ExecuteLoadItemsCommand());
+			}
+
+			async Task ExecuteLoadItemsCommand()
+			{
+				if (IsBusy)
+					return;
+
+				IsBusy = true;
+
+				try
+				{
+					Items.Clear();
+					var items = await DataStore.GetItemsAsync(true);
+					foreach (var item in items)
+					{
+						Items.Add(item);
+					}
+				}
+				catch (Exception ex)
+				{
+					Debug.WriteLine(ex);
+				}
+				finally
+				{
+					IsBusy = false;
+				}
+			}
+		}
+
+		ItemsViewModel viewModel;
+
+		protected override void Init()
+		{
+			SetBinding(
+				TitleProperty,
+				new Binding("Title")
+			 );
+
+			BindingContext = viewModel = new ItemsViewModel();
+
+			var listView = new ListView(ListViewCachingStrategy.RecycleElement)
+			{
+				VerticalOptions = LayoutOptions.FillAndExpand,
+				HasUnevenRows = true,
+				IsPullToRefreshEnabled = true,
+				RowHeight = 200
+			};
+
+			listView.SetBinding(
+				ListView.ItemsSourceProperty,
+				new Binding("Items")
+			);
+
+			listView.SetBinding(
+				ListView.RefreshCommandProperty,
+				new Binding("LoadItemsCommand")
+			);
+
+			listView.SetBinding(
+				ListView.IsRefreshingProperty,
+				new Binding("IsBusy", mode: BindingMode.OneWay)
+			);
+
+			listView.ItemTemplate = new DataTemplate(typeof(MyViewCell));
+
+			Content = listView;
+		}
+
+		protected override void OnAppearing()
+		{
+			base.OnAppearing();
+
+			if (viewModel.Items.Count == 0)
+				viewModel.LoadItemsCommand.Execute(null);
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -414,6 +414,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue1436.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)GitHub1567.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1909.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla60699.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)_Template.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42620.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1028.cs" />