added conversions from AIFunction to various OpenAI tools

Author: KrzysztofCwalina

test/Libraries/Microsoft.Extensions.AI.OpenAI.Tests/OpenAIAIFunctionConversionTests.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using OpenAI.Chat;
+using OpenAI.RealtimeConversation;
+using OpenAI.Responses;
+using Xunit;
+
+#pragma warning disable S103 // Lines should not be too long
+
+namespace Microsoft.Extensions.AI;
+
+public class OpenAIAIFunctionConversionTests
+{
+    // Test implementation of AIFunction
+    private class TestAIFunction : AIFunction
+    {
+        public TestAIFunction(string name, string description, Dictionary<string, object> jsonSchema)
+        {
+            Name = name;
+            Description = description;
+            JsonSchema = System.Text.Json.JsonSerializer.SerializeToElement(jsonSchema);
+        }
+
+        public override string Name { get; }
+        public override string Description { get; }
+        public override JsonElement JsonSchema { get; }
+        protected override async ValueTask<object?> InvokeCoreAsync(AIFunctionArguments arguments, CancellationToken cancellationToken) => await Task.FromResult<object?>(null);
+    }
+
+    // Shared schema for all tests
+    private static readonly Dictionary<string, object> _testFunctionSchema = new()
+    {
+        ["type"] = "object",
+        ["properties"] = new Dictionary<string, object>
+        {
+            ["name"] = new Dictionary<string, object>
+            {
+                ["type"] = "string",
+                ["description"] = "The name parameter"
+            }
+        },
+        ["required"] = new[] { "name" }
+    };
+
+    // Helper method to validate function parameters match our schema
+    private static void ValidateSchemaParameters(BinaryData parameters)
+    {
+        Assert.NotNull(parameters);
+
+        using var jsonDoc = JsonDocument.Parse(parameters);
+        var root = jsonDoc.RootElement;
+
+        Assert.Equal("object", root.GetProperty("type").GetString());
+        Assert.True(root.TryGetProperty("properties", out var properties));
+        Assert.True(properties.TryGetProperty("name", out var nameProperty));
+        Assert.Equal("string", nameProperty.GetProperty("type").GetString());
+        Assert.Equal("The name parameter", nameProperty.GetProperty("description").GetString());
+    }
+
+    [Fact]
+    public void AIFunctionToChatToolConversionWorks()
+    {
+        AIFunction aiFunction = new TestAIFunction(
+            "test_function",
+            "A test function for conversion",
+            _testFunctionSchema);
+
+        ChatTool chatTool = aiFunction.AsOpenAIChatTool();
+
+        Assert.NotNull(chatTool);
+        Assert.Equal("test_function", chatTool.FunctionName);
+        Assert.Equal("A test function for conversion", chatTool.FunctionDescription);
+        ValidateSchemaParameters(chatTool.FunctionParameters);
+    }
+
+    [Fact]
+    public void AIFunctionToResponseToolConversionWorks()
+    {
+        AIFunction aiFunction = new TestAIFunction(
+            "test_function",
+            "A test function for conversion",
+            _testFunctionSchema);
+
+        ResponseTool responseTool = aiFunction.AsOpenAIResponseTool();
+
+        Assert.NotNull(responseTool);
+    }
+
+    [Fact]
+    public void AIFunctionToConversationFunctionToolConversionWorks()
+    {
+        AIFunction aiFunction = new TestAIFunction(
+            "test_function",
+            "A test function for conversion",
+            _testFunctionSchema);
+
+        ConversationFunctionTool conversationTool = aiFunction.AsOpenAIConversationFunctionTool();
+
+        Assert.NotNull(conversationTool);
+        Assert.Equal("test_function", conversationTool.Name);
+        Assert.Equal("A test function for conversion", conversationTool.Description);
+        ValidateSchemaParameters(conversationTool.Parameters);
+    }
+}