Revert "test: remove .NET compaction tests causing Windows CI fixture issues"

This reverts commit bc261a3.

Author: jmoseley

dotnet/test/CompactionTests.cs

@@ -0,0 +1,112 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
+using System.Runtime.InteropServices;
+using GitHub.Copilot.SDK.Test.Harness;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace GitHub.Copilot.SDK.Test;
+
+public class CompactionTests(E2ETestFixture fixture, ITestOutputHelper output) : E2ETestBase(fixture, "compaction", output)
+{
+    [Fact(Skip = "Compaction tests are flaky on Windows CI - proxy startup timing issues")]
+    [Trait("Category", "SkipOnWindows")]
+    public async Task Should_Trigger_Compaction_With_Low_Threshold_And_Emit_Events()
+    {
+        // Create session with very low compaction thresholds to trigger compaction quickly
+        var session = await Client.CreateSessionAsync(new SessionConfig
+        {
+            InfiniteSessions = new InfiniteSessionConfig
+            {
+                Enabled = true,
+                // Trigger background compaction at 0.5% context usage (~1000 tokens)
+                BackgroundCompactionThreshold = 0.005,
+                // Block at 1% to ensure compaction runs
+                BufferExhaustionThreshold = 0.01
+            }
+        });
+
+        var compactionStartEvents = new List<SessionCompactionStartEvent>();
+        var compactionCompleteEvents = new List<SessionCompactionCompleteEvent>();
+
+        session.On(evt =>
+        {
+            if (evt is SessionCompactionStartEvent startEvt)
+            {
+                compactionStartEvents.Add(startEvt);
+            }
+            if (evt is SessionCompactionCompleteEvent completeEvt)
+            {
+                compactionCompleteEvents.Add(completeEvt);
+            }
+        });
+
+        // Send multiple messages to fill up the context window
+        await session.SendAndWaitAsync(new MessageOptions
+        {
+            Prompt = "Tell me a long story about a dragon. Be very detailed."
+        });
+        await session.SendAndWaitAsync(new MessageOptions
+        {
+            Prompt = "Continue the story with more details about the dragon's castle."
+        });
+        await session.SendAndWaitAsync(new MessageOptions
+        {
+            Prompt = "Now describe the dragon's treasure in great detail."
+        });
+
+        // Should have triggered compaction at least once
+        Assert.True(compactionStartEvents.Count >= 1, "Expected at least 1 compaction_start event");
+        Assert.True(compactionCompleteEvents.Count >= 1, "Expected at least 1 compaction_complete event");
+
+        // Compaction should have succeeded
+        var lastComplete = compactionCompleteEvents[^1];
+        Assert.True(lastComplete.Data.Success, "Expected compaction to succeed");
+
+        // Should have removed some tokens
+        if (lastComplete.Data.TokensRemoved.HasValue)
+        {
+            Assert.True(lastComplete.Data.TokensRemoved > 0, "Expected tokensRemoved > 0");
+        }
+
+        // Verify the session still works after compaction
+        var answer = await session.SendAndWaitAsync(new MessageOptions
+        {
+            Prompt = "What was the story about?"
+        });
+        Assert.NotNull(answer);
+        Assert.NotNull(answer!.Data.Content);
+        // Should remember it was about a dragon (context preserved via summary)
+        Assert.Contains("dragon", answer.Data.Content.ToLower());
+    }
+
+    [Fact(Skip = "Compaction tests are flaky on Windows CI - proxy startup timing issues")]
+    [Trait("Category", "SkipOnWindows")]
+    public async Task Should_Not_Emit_Compaction_Events_When_Infinite_Sessions_Disabled()
+    {
+        var session = await Client.CreateSessionAsync(new SessionConfig
+        {
+            InfiniteSessions = new InfiniteSessionConfig
+            {
+                Enabled = false
+            }
+        });
+
+        var compactionEvents = new List<SessionEvent>();
+
+        session.On(evt =>
+        {
+            if (evt is SessionCompactionStartEvent or SessionCompactionCompleteEvent)
+            {
+                compactionEvents.Add(evt);
+            }
+        });
+
+        await session.SendAndWaitAsync(new MessageOptions { Prompt = "What is 2+2?" });
+
+        // Should not have any compaction events when disabled
+        Assert.Empty(compactionEvents);
+    }
+}