chore: import upstream snapshot with attribution

dotnet/tests/Foundry.Hosting.IntegrationTests/HappyPathHostedAgentTests.cs

@@ -0,0 +1,66 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Threading.Tasks;
+using Foundry.Hosting.IntegrationTests.Fixtures;
+
+namespace Foundry.Hosting.IntegrationTests;
+
+/// <summary>
+/// Basic round trip, streaming, and container-instruction behaviour for a hosted Responses agent.
+/// Store and session semantics live in <see cref="HostedResponsesStoreConfigTests"/>.
+/// </summary>
+[Trait("Category", "FoundryHostedAgents")]
+public sealed class HappyPathHostedAgentTests(HappyPathHostedAgentFixture fixture) : IClassFixture<HappyPathHostedAgentFixture>
+{
+    private readonly HappyPathHostedAgentFixture _fixture = fixture;
+
+    [Fact]
+    public async Task RunAsync_ReturnsNonEmptyTextAsync()
+    {
+        // Arrange
+        var agent = this._fixture.Agent;
+
+        // Act
+        var response = await agent.RunAsync("Reply with a short greeting.");
+
+        // Assert
+        Assert.False(string.IsNullOrWhiteSpace(response.Text));
+    }
+
+    [Fact]
+    public async Task RunStreamingAsync_YieldsAtLeastOneUpdateAsync()
+    {
+        // Arrange
+        var agent = this._fixture.Agent;
+
+        // Act
+        var collected = new System.Collections.Generic.List<string>();
+        await foreach (var update in agent.RunStreamingAsync("Reply with a short greeting."))
+        {
+            if (!string.IsNullOrEmpty(update.Text))
+            {
+                collected.Add(update.Text);
+            }
+        }
+
+        // Assert
+        Assert.NotEmpty(collected);
+        Assert.False(string.IsNullOrWhiteSpace(string.Concat(collected)));
+    }
+
+    [Fact]
+    public async Task Instructions_FromContainerDefinition_AreObeyedAsync()
+    {
+        // Arrange: the container-side happy-path instructions require every reply to end with the
+        // marker token CONTAINER-OK. See TestContainer/Program.cs.
+        var agent = this._fixture.Agent;
+
+        // Act
+        var response = await agent.RunAsync("Say something useful.");
+
+        // Assert
+        Assert.False(string.IsNullOrWhiteSpace(response.Text));
+        Assert.Contains("CONTAINER-OK", response.Text, StringComparison.OrdinalIgnoreCase);
+    }
+}