chore: import upstream snapshot with attribution

dotnet/tests/AgentConformance.IntegrationTests/IAgentFixture.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.Agents.AI;
+using Microsoft.Extensions.AI;
+
+namespace AgentConformance.IntegrationTests;
+
+/// <summary>
+/// Interface for setting up and tearing down agents, to be used in tests.
+/// Each agent type should have its own derived class.
+/// </summary>
+public interface IAgentFixture : IAsyncLifetime
+{
+    AIAgent Agent { get; }
+
+    Task<List<ChatMessage>> GetChatHistoryAsync(AIAgent agent, AgentSession session);
+
+    Task DeleteSessionAsync(AgentSession session);
+}