chore: import upstream snapshot with attribution

dotnet/tests/Microsoft.Agents.AI.UnitTests/Compaction/ContextWindowCompactionStrategyTests.cs

@@ -0,0 +1,219 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.Agents.AI.Compaction;
+using Microsoft.Extensions.AI;
+
+namespace Microsoft.Agents.AI.UnitTests.Compaction;
+
+/// <summary>
+/// Contains tests for the <see cref="ContextWindowCompactionStrategy"/> class.
+/// </summary>
+public class ContextWindowCompactionStrategyTests
+{
+    [Fact]
+    public void Constructor_ValidParameters_SetsProperties()
+    {
+        // Arrange & Act
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 1_050_000,
+            maxOutputTokens: 128_000);
+
+        // Assert
+        Assert.Equal(1_050_000, strategy.MaxContextWindowTokens);
+        Assert.Equal(128_000, strategy.MaxOutputTokens);
+        Assert.Equal(922_000, strategy.InputBudgetTokens);
+        Assert.Equal(ContextWindowCompactionStrategy.DefaultToolEvictionThreshold, strategy.ToolEvictionThreshold);
+        Assert.Equal(ContextWindowCompactionStrategy.DefaultTruncationThreshold, strategy.TruncationThreshold);
+    }
+
+    [Fact]
+    public void Constructor_CustomThresholds_SetsProperties()
+    {
+        // Arrange & Act
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 1_000_000,
+            maxOutputTokens: 100_000,
+            toolEvictionThreshold: 0.3,
+            truncationThreshold: 0.6);
+
+        // Assert
+        Assert.Equal(900_000, strategy.InputBudgetTokens);
+        Assert.Equal(0.3, strategy.ToolEvictionThreshold);
+        Assert.Equal(0.6, strategy.TruncationThreshold);
+    }
+
+    [Theory]
+    [InlineData(0, 100)]        // maxContextWindowTokens <= 0
+    [InlineData(-1, 100)]       // maxContextWindowTokens negative
+    public void Constructor_InvalidContextWindow_Throws(int contextWindow, int maxOutput)
+    {
+        // Act & Assert
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+            new ContextWindowCompactionStrategy(contextWindow, maxOutput));
+    }
+
+    [Theory]
+    [InlineData(1000, -1)]       // maxOutputTokens negative
+    [InlineData(1000, 1000)]     // maxOutputTokens == contextWindow
+    [InlineData(1000, 1001)]     // maxOutputTokens > contextWindow
+    public void Constructor_InvalidOutputTokens_Throws(int contextWindow, int maxOutput)
+    {
+        // Act & Assert
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+            new ContextWindowCompactionStrategy(contextWindow, maxOutput));
+    }
+
+    [Theory]
+    [InlineData(0.0)]   // Zero threshold
+    [InlineData(-0.1)]  // Negative threshold
+    [InlineData(1.1)]   // Over 1.0
+    public void Constructor_InvalidToolEvictionThreshold_Throws(double threshold)
+    {
+        // Act & Assert
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+            new ContextWindowCompactionStrategy(1000, 100, toolEvictionThreshold: threshold));
+    }
+
+    [Theory]
+    [InlineData(0.0)]   // Zero threshold
+    [InlineData(-0.1)]  // Negative threshold
+    [InlineData(1.1)]   // Over 1.0
+    public void Constructor_InvalidTruncationThreshold_Throws(double threshold)
+    {
+        // Act & Assert
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+            new ContextWindowCompactionStrategy(1000, 100, truncationThreshold: threshold));
+    }
+
+    [Fact]
+    public void Constructor_TruncationBelowToolEviction_Throws()
+    {
+        // Act & Assert
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+            new ContextWindowCompactionStrategy(1000, 100, toolEvictionThreshold: 0.8, truncationThreshold: 0.5));
+    }
+
+    [Fact]
+    public async Task CompactAsync_BelowToolEvictionThreshold_NoCompactionAsync()
+    {
+        // Arrange — input budget = 900 tokens, tool eviction at 450, truncation at 720
+        // A few short messages should be well below any threshold.
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 1000,
+            maxOutputTokens: 100);
+
+        CompactionMessageIndex index = CompactionMessageIndex.Create(
+        [
+            new ChatMessage(ChatRole.User, "Hello"),
+            new ChatMessage(ChatRole.Assistant, "Hi there!"),
+        ]);
+
+        // Act
+        bool result = await strategy.CompactAsync(index);
+
+        // Assert
+        Assert.False(result);
+        Assert.Equal(2, index.IncludedGroupCount);
+    }
+
+    [Fact]
+    public async Task CompactAsync_AboveTruncationThreshold_TruncatesOldestAsync()
+    {
+        // Arrange — use a budget of 5 tokens with truncation at 80% = 4 token threshold.
+        // Even the shortest messages will exceed this, ensuring truncation fires.
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 10,
+            maxOutputTokens: 5,
+            toolEvictionThreshold: 0.5,
+            truncationThreshold: 0.8);
+
+        // Verify internal budget calculation
+        Assert.Equal(5, strategy.InputBudgetTokens);
+
+        CompactionMessageIndex index = CompactionMessageIndex.Create(
+        [
+            new ChatMessage(ChatRole.User, "First user message"),
+            new ChatMessage(ChatRole.Assistant, "First response"),
+            new ChatMessage(ChatRole.User, "Second user message"),
+            new ChatMessage(ChatRole.Assistant, "Second response"),
+        ]);
+
+        int groupsBefore = index.IncludedGroupCount;
+        int tokensBefore = index.IncludedTokenCount;
+
+        // Verify tokens actually exceed the truncation threshold (80% of 5 = 4)
+        Assert.True(tokensBefore > 4, $"Expected tokens > 4 but got {tokensBefore}");
+        Assert.True(groupsBefore > 1, $"Expected groups > 1 but got {groupsBefore}");
+
+        // Act
+        bool result = await strategy.CompactAsync(index);
+
+        // Assert — with tokens well above a 4-token threshold, truncation should fire
+        Assert.True(result, $"Expected compaction to occur. Tokens before: {tokensBefore}, groups before: {groupsBefore}, NonSystemGroups: {index.IncludedNonSystemGroupCount}");
+        Assert.True(index.IncludedGroupCount < groupsBefore);
+    }
+
+    [Fact]
+    public async Task CompactAsync_ToolCallsAboveEvictionThreshold_CollapsesToolCallsAsync()
+    {
+        // Arrange — very small budget so tool eviction fires.
+        // Input budget = 5, tool eviction at 50% = 2 token threshold.
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 10,
+            maxOutputTokens: 5,
+            toolEvictionThreshold: 0.5,
+            truncationThreshold: 0.9);
+
+        // Build messages with a tool call group: assistant with FunctionCallContent + tool result
+        var assistantMessage = new ChatMessage(ChatRole.Assistant, [new FunctionCallContent("call1", "get_data", arguments: new Dictionary<string, object?> { ["query"] = "test" })]);
+        var toolResultMessage = new ChatMessage(ChatRole.Tool, [new FunctionResultContent("call1", "Here is a long result with many words to ensure we exceed the token threshold")]);
+        var userMessage = new ChatMessage(ChatRole.User, "What did you find?");
+        var assistantResponse = new ChatMessage(ChatRole.Assistant, "Based on the results I found information.");
+
+        CompactionMessageIndex index = CompactionMessageIndex.Create(
+        [
+            assistantMessage,
+            toolResultMessage,
+            userMessage,
+            assistantResponse,
+        ]);
+
+        // Act
+        bool result = await strategy.CompactAsync(index);
+
+        // Assert — compaction should succeed for tool calls above the eviction threshold.
+        // Do not assert on IncludedTokenCount because tool-result compaction preserves content
+        // in summary form and tokenization can make the count stay the same or increase.
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void Constructor_EqualThresholds_Succeeds()
+    {
+        // Arrange & Act — truncation == tool eviction should be valid
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 1000,
+            maxOutputTokens: 100,
+            toolEvictionThreshold: 0.7,
+            truncationThreshold: 0.7);
+
+        // Assert
+        Assert.Equal(0.7, strategy.ToolEvictionThreshold);
+        Assert.Equal(0.7, strategy.TruncationThreshold);
+    }
+
+    [Fact]
+    public void Constructor_ZeroMaxOutputTokens_FullBudget()
+    {
+        // Arrange & Act
+        var strategy = new ContextWindowCompactionStrategy(
+            maxContextWindowTokens: 1_000_000,
+            maxOutputTokens: 0);
+
+        // Assert — entire context window is the input budget
+        Assert.Equal(1_000_000, strategy.InputBudgetTokens);
+    }
+}