Merge pull request #1695 from unoplatform/dev/dr/vmCommands

test(mvux): Ensure that feed parameters shares the same context as the Model

src/Uno.Extensions.Reactive.UI.Tests/Generator/Given_VMWithCommands.cs

@@ -0,0 +1,77 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Data;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Uno.Extensions.Reactive.UI;
+using Uno.UI.RuntimeTests;
+using Button = Microsoft.UI.Xaml.Controls.Button;
+
+namespace Uno.Extensions.Reactive.WinUI.Tests.Generator;
+
+[TestClass]
+[RunsOnUIThread]
+public partial class Given_VMWithCommands
+{
+	public partial class When_ParameterFeed_Then_SubscribedWithSameContext_ViewModel
+	{
+		public int FeedInvokeCount { get; private set; }
+
+		public int CommandLastParameter { get; private set; } = -1;
+
+		public IFeed<int> MyFeed => Feed.Async(async ct => ++FeedInvokeCount);
+
+		public void DoSomething(int myFeed, CancellationToken ct)
+			=> CommandLastParameter = myFeed;
+	}
+
+	[TestMethod]
+	public async Task When_ParameterFeed_Then_SubscribedWithSameContext()
+	{
+		var vm = new BindableWhen_ParameterFeed_Then_SubscribedWithSameContext_ViewModel();
+
+		await UIHelper.WaitFor(() => vm.MyFeed != 0, default);
+
+		var current = vm.MyFeed;
+		vm.DoSomething.Execute(null);
+
+		await UIHelper.WaitFor(() => vm.Model.CommandLastParameter != -1, default);
+
+		Assert.AreEqual(1, vm.FeedInvokeCount);
+		Assert.AreEqual(current, vm.Model.CommandLastParameter);
+	}
+
+	[TestMethod]
+	public async Task When_ParameterFeed_Then_SubscribedWithSameContext_UsingUI()
+	{
+		FeedView view;
+		Button doSomething;
+		var vm = new BindableWhen_ParameterFeed_Then_SubscribedWithSameContext_ViewModel();
+		var ui = new StackPanel
+		{
+			DataContext = vm,
+			Children =
+			{
+				(view = new FeedView()),
+				(doSomething = new Button())
+			}
+		};
+
+		view.SetBinding(FeedView.SourceProperty, new Binding { Path = new PropertyPath("MyFeed") });
+		doSomething.SetBinding(Button.CommandProperty, new Binding { Path = new PropertyPath("DoSomething") });
+
+		await UIHelper.Load(ui, default);
+
+		await UIHelper.WaitFor(() => vm.MyFeed is not 0, default);
+
+		var current = vm.MyFeed;
+		doSomething.Command.Execute(null);
+
+		await UIHelper.WaitFor(() => vm.Model.CommandLastParameter != -1, default);
+
+		Assert.AreEqual(1, vm.FeedInvokeCount);
+		Assert.AreEqual(current, vm.Model.CommandLastParameter);
+	}
+}

src/Uno.Extensions.Reactive/Utils/FeedUIHelper.cs

@@ -48,7 +48,17 @@ public static async IAsyncEnumerable<Message<T>> GetSource<T>(IFeed<T> feed, Sou
 		}
 	}
 
-	private static async ValueTask<IAsyncEnumerator<T>> GetSourceEnumerator<T>(ISignal<T> signal, SourceContext context)
+	private static async ValueTask<IAsyncEnumerator<Message<T>>> GetSourceEnumerator<T>(IFeed<T> signal, SourceContext context)
+	{
+		var ct = context.Token;
+		var src = DispatcherHelper.HasThreadAccess
+			? await Task.Run(() => context.GetOrCreateSource(signal), ct).ConfigureAwait(false)
+			: context.GetOrCreateSource(signal);
+
+		return src.GetAsyncEnumerator(ct);
+	}
+
+	private static async ValueTask<IAsyncEnumerator<TMessage>> GetSourceEnumerator<TMessage>(ISignal<TMessage> signal, SourceContext context)
 	{
 		var ct = context.Token;
 		var src = DispatcherHelper.HasThreadAccess