chore: import upstream snapshot with attribution

dotnet/tests/Microsoft.Agents.AI.Foundry.UnitTests/HttpHandlerAssert.cs

@@ -0,0 +1,40 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.Agents.AI.Foundry.UnitTests;
+
+internal sealed class HttpHandlerAssert : HttpClientHandler
+{
+    private readonly Func<HttpRequestMessage, HttpResponseMessage>? _assertion;
+    private readonly Func<HttpRequestMessage, Task<HttpResponseMessage>>? _assertionAsync;
+
+    public HttpHandlerAssert(Func<HttpRequestMessage, HttpResponseMessage> assertion)
+    {
+        this._assertion = assertion;
+    }
+    public HttpHandlerAssert(Func<HttpRequestMessage, Task<HttpResponseMessage>> assertionAsync)
+    {
+        this._assertionAsync = assertionAsync;
+    }
+
+    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        if (this._assertionAsync is not null)
+        {
+            return await this._assertionAsync.Invoke(request);
+        }
+
+        return this._assertion!.Invoke(request);
+    }
+
+#if NET
+    protected override HttpResponseMessage Send(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        return this._assertion!(request);
+    }
+#endif
+}