Hermetic real-MainWindow tests: LayoutPathOverride temp-DB seam (InternalsVisibleTo); fix tests persisting fake webcam sources over the real layout DB; LayoutStore delete-roundtrip guard

ytLive.Tests/LayoutStorePersistenceTests.cs

@@ -0,0 +1,50 @@
+using System;
+using System.IO;
+using Microsoft.Data.Sqlite;
+using Xunit;
+using ytLive.Models;
+using ytLive.Services;
+
+namespace ytLive.Tests;
+
+/// <summary>
+/// The layout DB is a full rewrite on every save (DELETE all scenes/sources,
+/// re-insert from memory). This guards the round trip: sources the user deletes
+/// in the UI must not come back after a save + reload.
+/// </summary>
+public class LayoutStorePersistenceTests
+{
+    [Fact]
+    public void Deleted_Webcam_Source_Does_Not_Return_After_Save_And_Reload()
+    {
+        var path = Path.Combine(Path.GetTempPath(), $"ytLlive-layout-{Guid.NewGuid():N}.db");
+        try
+        {
+            using var store = new LayoutStore(path);
+            var scene = new Scene { Name = "Starting" };
+            scene.Sources.Add(new Source
+            {
+                Name = "Webcam",
+                Type = SourceType.Webcam,
+                DeviceId = "real-device",
+                Width = 480,
+                Height = 270,
+            });
+            store.Save(new[] { scene });
+
+            var reloaded = store.Load();
+            Assert.Single(reloaded[0].Sources);
+
+            reloaded[0].Sources.RemoveAt(0);
+            store.Save(reloaded);
+
+            var afterDelete = store.Load();
+            Assert.Empty(afterDelete[0].Sources);
+        }
+        finally
+        {
+            SqliteConnection.ClearAllPools();
+            try { File.Delete(path); } catch { /* best-effort cleanup */ }
+        }
+    }
+}

ytLive.Tests/RoundClipInteractionTests.cs

@@ -5,6 +5,7 @@ using System.Windows.Controls;
 using System.Windows.Media;
 using System.Windows.Shapes;
 using System.Windows.Threading;
+using Microsoft.Data.Sqlite;
 using Xunit;
 using ytLive.Models;
 using ytLive.ViewModels;
@@ -47,6 +48,11 @@ public sealed class RoundClipInteractionTests
         var app = new App();
         app.InitializeComponent();
 
+        // Never let the real MainWindow read/write the user's actual layout DB —
+        // Shutdown() saves the layout, which would persist these test sources
+        // over the real ones. Point it at a throwaway temp DB instead.
+        var tempDb = System.IO.Path.Combine(System.IO.Path.GetTempPath(), $"ytLlive-test-{Guid.NewGuid():N}.db");
+        MainViewModel.LayoutPathOverride = tempDb;
         var window = new MainWindow();
         var vm = (MainViewModel)window.DataContext;
         try
@@ -103,6 +109,9 @@ public sealed class RoundClipInteractionTests
         finally
         {
             window.Close();
+            MainViewModel.LayoutPathOverride = null;
+            SqliteConnection.ClearAllPools();
+            try { System.IO.File.Delete(tempDb); } catch { /* best-effort cleanup */ }
         }
     }