From 8b6311710ea795f648a5300d7b65cf9e1fcd9ebe Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Thu, 27 Apr 2023 23:15:51 -0400
Subject: [PATCH] Check for SupportsRunLoops

---
 src/Headless/Avalonia.Headless/HeadlessUnitTestSession.cs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Headless/Avalonia.Headless/HeadlessUnitTestSession.cs b/src/Headless/Avalonia.Headless/HeadlessUnitTestSession.cs
index a3059c6d3e..12f8515209 100644
--- a/src/Headless/Avalonia.Headless/HeadlessUnitTestSession.cs
+++ b/src/Headless/Avalonia.Headless/HeadlessUnitTestSession.cs
@@ -89,6 +89,11 @@ public sealed class HeadlessUnitTestSession : IDisposable
 
                 appBuilder.SetupWithoutStarting();
 
+                if (!Dispatcher.UIThread.SupportsRunLoops)
+                {
+                    throw new InvalidOperationException("Avalonia Headless platform has failed to initialize.");
+                }
+                
                 // ReSharper disable once AccessToModifiedClosure
                 tcs.SetResult(new HeadlessUnitTestSession(entryPointType, Application.Current!,
                     SynchronizationContext.Current!, Dispatcher.UIThread, cancellationTokenSource));