added sending closing event message to settings windows (#7)

Reviewed-on: #7
Co-authored-by: Aleksandr Neychev <alexnejchev73@gmail.com>

CursorLang.Agent.Tests/EndToEndTests.cs

@@ -133,6 +133,34 @@ public sealed partial class EndToEndTests
         Assert.False(launch.Process.HasExited);
     }
 
+    /// <summary>
+    /// "Exit" in the tray menu ends the application whole: the settings window goes with
+    /// the agent instead of staying on the screen belonging to nothing.
+    /// </summary>
+    /// <remarks>
+    /// The menu itself is out of reach of a test — it is a <c>TrackPopupMenuEx</c> menu
+    /// with a modal loop of its own — so what is checked is the request the menu makes.
+    /// The settings window here is the real one, started by the agent, and it must be
+    /// listening by the time it is on the screen.
+    /// </remarks>
+    [Fact]
+    public void The_agents_exit_closes_the_settings_window()
+    {
+        using Launch launch = Launch.Start();
+        launch.WaitForSettingsWindow();
+
+        Process settings = Launch.SettingsProcesses().Single();
+        try
+        {
+            Assert.True(SettingsCloseSignal.RequestClose(), "the settings window was not listening");
+            Assert.True(settings.WaitForExit(ExitTimeout), "the settings window outlived the agent's exit");
+        }
+        finally
+        {
+            settings.Dispose();
+        }
+    }
+
     /// <summary>A started application that shuts down together with the check.</summary>
     private sealed class Launch : IDisposable
     {