diff --git a/.dotnet/CHANGELOG.md b/.dotnet/CHANGELOG.md
index 424fb2758..cfc9786fb 100644
--- a/.dotnet/CHANGELOG.md
+++ b/.dotnet/CHANGELOG.md
@@ -4,6 +4,9 @@
 
 ### Features Added
 
+- Added the following model factory (a static class that can be used to instantiate OpenAI models for mocking in non-live test scenarios):
+  - `OpenAIChatModelFactory` in the `OpenAI.Chat` namespace
+
 ### Breaking Changes
 
 - Updated fine-tuning pagination methods `GetJobs`, `GetEvents`, and `GetJobCheckpoints` to return `IEnumerable<ClientResult>` instead of `ClientResult`. (commit_hash)
diff --git a/.dotnet/api/OpenAI.netstandard2.0.cs b/.dotnet/api/OpenAI.netstandard2.0.cs
index 61c2c7f6d..87abb883d 100644
--- a/.dotnet/api/OpenAI.netstandard2.0.cs
+++ b/.dotnet/api/OpenAI.netstandard2.0.cs
@@ -1529,6 +1529,15 @@ public class FunctionChatMessage : ChatMessage, IJsonModel<FunctionChatMessage>,
         public static bool operator !=(ImageChatMessageContentPartDetail left, ImageChatMessageContentPartDetail right);
         public override readonly string ToString();
     }
+    public static class OpenAIChatModelFactory {
+        public static ChatCompletion ChatCompletion(string id = null, ChatFinishReason finishReason = ChatFinishReason.Stop, IEnumerable<ChatMessageContentPart> content = null, string refusal = null, IEnumerable<ChatToolCall> toolCalls = null, ChatMessageRole role = ChatMessageRole.System, ChatFunctionCall functionCall = null, IEnumerable<ChatTokenLogProbabilityInfo> contentTokenLogProbabilities = null, IEnumerable<ChatTokenLogProbabilityInfo> refusalTokenLogProbabilities = null, DateTimeOffset createdAt = default, string model = null, string systemFingerprint = null, ChatTokenUsage usage = null);
+        public static ChatTokenLogProbabilityInfo ChatTokenLogProbabilityInfo(string token = null, float logProbability = 0, IEnumerable<int> utf8ByteValues = null, IEnumerable<ChatTokenTopLogProbabilityInfo> topLogProbabilities = null);
+        public static ChatTokenTopLogProbabilityInfo ChatTokenTopLogProbabilityInfo(string token = null, float logProbability = 0, IEnumerable<int> utf8ByteValues = null);
+        public static ChatTokenUsage ChatTokenUsage(int outputTokens = 0, int inputTokens = 0, int totalTokens = 0);
+        public static StreamingChatCompletionUpdate StreamingChatCompletionUpdate(string id = null, IEnumerable<ChatMessageContentPart> contentUpdate = null, StreamingChatFunctionCallUpdate functionCallUpdate = null, IEnumerable<StreamingChatToolCallUpdate> toolCallUpdates = null, ChatMessageRole? role = null, string refusalUpdate = null, IEnumerable<ChatTokenLogProbabilityInfo> contentTokenLogProbabilities = null, IEnumerable<ChatTokenLogProbabilityInfo> refusalTokenLogProbabilities = null, ChatFinishReason? finishReason = null, DateTimeOffset createdAt = default, string model = null, string systemFingerprint = null, ChatTokenUsage usage = null);
+        public static StreamingChatFunctionCallUpdate StreamingChatFunctionCallUpdate(string functionArgumentsUpdate = null, string functionName = null);
+        public static StreamingChatToolCallUpdate StreamingChatToolCallUpdate(int index = 0, string id = null, ChatToolCallKind kind = default, string functionName = null, string functionArgumentsUpdate = null);
+    }
     public class StreamingChatCompletionUpdate : IJsonModel<StreamingChatCompletionUpdate>, IPersistableModel<StreamingChatCompletionUpdate> {
         public IReadOnlyList<ChatTokenLogProbabilityInfo> ContentTokenLogProbabilities { get; }
         public IReadOnlyList<ChatMessageContentPart> ContentUpdate { get; }
diff --git a/.dotnet/src/Custom/Chat/OpenAIChatModelFactory.cs b/.dotnet/src/Custom/Chat/OpenAIChatModelFactory.cs
new file mode 100644
index 000000000..4ba814372
--- /dev/null
+++ b/.dotnet/src/Custom/Chat/OpenAIChatModelFactory.cs
@@ -0,0 +1,187 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenAI.Chat;
+
+/// <summary> Model factory for models. </summary>
+public static partial class OpenAIChatModelFactory
+{
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.ChatCompletion"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.ChatCompletion"/> instance for mocking. </returns>
+    public static ChatCompletion ChatCompletion(
+        string id = null,
+        ChatFinishReason finishReason = default,
+        IEnumerable<ChatMessageContentPart> content = null,
+        string refusal = null,
+        IEnumerable<ChatToolCall> toolCalls = null,
+        ChatMessageRole role = default,
+        ChatFunctionCall functionCall = null,
+        IEnumerable<ChatTokenLogProbabilityInfo> contentTokenLogProbabilities = null,
+        IEnumerable<ChatTokenLogProbabilityInfo> refusalTokenLogProbabilities = null,
+        DateTimeOffset createdAt = default,
+        string model = null,
+        string systemFingerprint = null,
+        ChatTokenUsage usage = null)
+    {
+        content ??= new List<ChatMessageContentPart>();
+        toolCalls ??= new List<ChatToolCall>();
+        contentTokenLogProbabilities ??= new List<ChatTokenLogProbabilityInfo>();
+        refusalTokenLogProbabilities ??= new List<ChatTokenLogProbabilityInfo>();
+
+        InternalChatCompletionResponseMessage message = new InternalChatCompletionResponseMessage(
+            content.ToList(),
+            refusal,
+            toolCalls.ToList(),
+            role,
+            functionCall,
+            serializedAdditionalRawData: null);
+
+        InternalCreateChatCompletionResponseChoiceLogprobs logprobs = new InternalCreateChatCompletionResponseChoiceLogprobs(
+            contentTokenLogProbabilities.ToList(),
+            refusalTokenLogProbabilities.ToList(),
+            serializedAdditionalRawData: null);
+
+        IReadOnlyList<InternalCreateChatCompletionResponseChoice> choices = [
+            new InternalCreateChatCompletionResponseChoice(
+                finishReason,
+                index: 0,
+                message,
+                logprobs,
+                serializedAdditionalRawData: null)
+        ];
+
+        return new ChatCompletion(
+            id,
+            choices,
+            createdAt,
+            model,
+            serviceTier: null,
+            systemFingerprint,
+            InternalCreateChatCompletionResponseObject.ChatCompletion,
+            usage,
+            serializedAdditionalRawData: null);
+    }
+
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.ChatTokenLogProbabilityInfo"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.ChatTokenLogProbabilityInfo"/> instance for mocking. </returns>
+    public static ChatTokenLogProbabilityInfo ChatTokenLogProbabilityInfo(string token = null, float logProbability = default, IEnumerable<int> utf8ByteValues = null, IEnumerable<ChatTokenTopLogProbabilityInfo> topLogProbabilities = null)
+    {
+        utf8ByteValues ??= new List<int>();
+        topLogProbabilities ??= new List<ChatTokenTopLogProbabilityInfo>();
+
+        return new ChatTokenLogProbabilityInfo(
+            token,
+            logProbability,
+            utf8ByteValues.ToList(),
+            topLogProbabilities.ToList(),
+            serializedAdditionalRawData: null);
+    }
+
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.ChatTokenTopLogProbabilityInfo"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.ChatTokenTopLogProbabilityInfo"/> instance for mocking. </returns>
+    public static ChatTokenTopLogProbabilityInfo ChatTokenTopLogProbabilityInfo(string token = null, float logProbability = default, IEnumerable<int> utf8ByteValues = null)
+    {
+        utf8ByteValues ??= new List<int>();
+
+        return new ChatTokenTopLogProbabilityInfo(
+            token,
+            logProbability,
+            utf8ByteValues.ToList(),
+            serializedAdditionalRawData: null);
+    }
+
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.ChatTokenUsage"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.ChatTokenUsage"/> instance for mocking. </returns>
+    public static ChatTokenUsage ChatTokenUsage(int outputTokens = default, int inputTokens = default, int totalTokens = default)
+    {
+        return new ChatTokenUsage(
+            outputTokens,
+            inputTokens,
+            totalTokens,
+            serializedAdditionalRawData: null);
+    }
+
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.StreamingChatCompletionUpdate"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.StreamingChatCompletionUpdate"/> instance for mocking. </returns>
+    public static StreamingChatCompletionUpdate StreamingChatCompletionUpdate(
+        string id = null,
+        IEnumerable<ChatMessageContentPart> contentUpdate = null,
+        StreamingChatFunctionCallUpdate functionCallUpdate = null,
+        IEnumerable<StreamingChatToolCallUpdate> toolCallUpdates = null,
+        ChatMessageRole? role = null,
+        string refusalUpdate = null,
+        IEnumerable<ChatTokenLogProbabilityInfo> contentTokenLogProbabilities = null,
+        IEnumerable<ChatTokenLogProbabilityInfo> refusalTokenLogProbabilities = null,
+        ChatFinishReason? finishReason = null,
+        DateTimeOffset createdAt = default,
+        string model = null,
+        string systemFingerprint = null,
+        ChatTokenUsage usage = null)
+    {
+        contentUpdate ??= new List<ChatMessageContentPart>();
+        toolCallUpdates ??= new List<StreamingChatToolCallUpdate>();
+        contentTokenLogProbabilities ??= new List<ChatTokenLogProbabilityInfo>();
+        refusalTokenLogProbabilities ??= new List<ChatTokenLogProbabilityInfo>();
+
+        InternalChatCompletionStreamResponseDelta delta = new InternalChatCompletionStreamResponseDelta(
+            contentUpdate.ToList(),
+            functionCallUpdate,
+            toolCallUpdates.ToList(),
+            role,
+            refusalUpdate,
+            serializedAdditionalRawData: null);
+
+        InternalCreateChatCompletionStreamResponseChoiceLogprobs logprobs = new InternalCreateChatCompletionStreamResponseChoiceLogprobs(
+            contentTokenLogProbabilities.ToList(),
+            refusalTokenLogProbabilities.ToList(),
+            serializedAdditionalRawData: null);
+
+        IReadOnlyList<InternalCreateChatCompletionStreamResponseChoice> choices = [
+            new InternalCreateChatCompletionStreamResponseChoice(
+                delta,
+                logprobs,
+                finishReason,
+                index: 0,
+                serializedAdditionalRawData: null)
+        ];
+
+        return new StreamingChatCompletionUpdate(
+            id,
+            choices,
+            createdAt,
+            model,
+            serviceTier: null,
+            systemFingerprint,
+            InternalCreateChatCompletionStreamResponseObject.ChatCompletionChunk,
+            usage,
+            serializedAdditionalRawData: null);
+    }
+
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.StreamingChatFunctionCallUpdate"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.StreamingChatFunctionCallUpdate"/> instance for mocking. </returns>
+    public static StreamingChatFunctionCallUpdate StreamingChatFunctionCallUpdate(string functionArgumentsUpdate = null, string functionName = null)
+    {
+        return new StreamingChatFunctionCallUpdate(
+            functionArgumentsUpdate,
+            functionName,
+            serializedAdditionalRawData: null);
+    }
+
+    /// <summary> Initializes a new instance of <see cref="OpenAI.Chat.StreamingChatToolCallUpdate"/>. </summary>
+    /// <returns> A new <see cref="OpenAI.Chat.StreamingChatToolCallUpdate"/> instance for mocking. </returns>
+    public static StreamingChatToolCallUpdate StreamingChatToolCallUpdate(int index = default, string id = null, ChatToolCallKind kind = default, string functionName = null, string functionArgumentsUpdate = null)
+    {
+        InternalChatCompletionMessageToolCallChunkFunction function = new InternalChatCompletionMessageToolCallChunkFunction(
+            functionName,
+            functionArgumentsUpdate,
+            serializedAdditionalRawData: null);
+
+        return new StreamingChatToolCallUpdate(
+            index,
+            id,
+            kind,
+            function,
+            serializedAdditionalRawData: null);
+    }
+}
diff --git a/.dotnet/tests/Chat/OpenAIChatModelFactoryTests.cs b/.dotnet/tests/Chat/OpenAIChatModelFactoryTests.cs
new file mode 100644
index 000000000..2255c8d55
--- /dev/null
+++ b/.dotnet/tests/Chat/OpenAIChatModelFactoryTests.cs
@@ -0,0 +1,876 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using OpenAI.Chat;
+
+namespace OpenAI.Tests.Chat;
+
+[Parallelizable(ParallelScope.All)]
+[Category("Smoke")]
+public partial class OpenAIChatModelFactoryTests
+{
+    [Test]
+    public void ChatCompletionWithNoPropertiesWorks()
+    {
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion();
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithIdWorks()
+    {
+        string id = "chat_completion_id";
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(id: id);
+
+        Assert.That(chatCompletion.Id, Is.EqualTo(id));
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithFinishReasonWorks()
+    {
+        ChatFinishReason finishReason = ChatFinishReason.ToolCalls;
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(finishReason: finishReason);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(finishReason));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithContentWorks()
+    {
+        IEnumerable<ChatMessageContentPart> content = [
+            ChatMessageContentPart.CreateTextMessageContentPart("first part"),
+            ChatMessageContentPart.CreateTextMessageContentPart("second part")
+        ];
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(content: content);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content.SequenceEqual(content), Is.True);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithRefusalWorks()
+    {
+        string refusal = "This is a refusal.";
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(refusal: refusal);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.EqualTo(refusal));
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithToolCallsWorks()
+    {
+        IEnumerable<ChatToolCall> toolCalls = [
+            ChatToolCall.CreateFunctionToolCall("id1", "get_recipe", string.Empty),
+            ChatToolCall.CreateFunctionToolCall("id2", "get_location", string.Empty)
+        ];
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(toolCalls: toolCalls);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls.SequenceEqual(toolCalls), Is.True);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithRoleWorks()
+    {
+        ChatMessageRole role = ChatMessageRole.Tool;
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(role: role);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(role));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithFunctionCallWorks()
+    {
+        ChatFunctionCall functionCall = new ChatFunctionCall("get_recipe", string.Empty);
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(functionCall: functionCall);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.EqualTo(functionCall));
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithContentTokenLogProbabilitiesWorks()
+    {
+        IEnumerable<ChatTokenLogProbabilityInfo> contentTokenLogProbabilities = [
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 1f),
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 2f)
+        ];
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(contentTokenLogProbabilities: contentTokenLogProbabilities);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities.SequenceEqual(contentTokenLogProbabilities), Is.True);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithRefusalTokenLogProbabilitiesWorks()
+    {
+        IEnumerable<ChatTokenLogProbabilityInfo> refusalTokenLogProbabilities = [
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 1f),
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 2f)
+        ];
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(refusalTokenLogProbabilities: refusalTokenLogProbabilities);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities.SequenceEqual(refusalTokenLogProbabilities), Is.True);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithCreatedAtWorks()
+    {
+        DateTimeOffset createdAt = DateTimeOffset.UtcNow;
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(createdAt: createdAt);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(createdAt));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithModelWorks()
+    {
+        string model = "topmodel";
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(model: model);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.EqualTo(model));
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithSystemFingerprintWorks()
+    {
+        string systemFingerprint = "footprint";
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(systemFingerprint: systemFingerprint);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.EqualTo(systemFingerprint));
+        Assert.That(chatCompletion.Usage, Is.Null);
+    }
+
+    [Test]
+    public void ChatCompletionWithUsageWorks()
+    {
+        ChatTokenUsage usage = OpenAIChatModelFactory.ChatTokenUsage(outputTokens: 20);
+        ChatCompletion chatCompletion = OpenAIChatModelFactory.ChatCompletion(usage: usage);
+
+        Assert.That(chatCompletion.Id, Is.Null);
+        Assert.That(chatCompletion.FinishReason, Is.EqualTo(default(ChatFinishReason)));
+        Assert.That(chatCompletion.Content, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Refusal, Is.Null);
+        Assert.That(chatCompletion.ToolCalls, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.Role, Is.EqualTo(default(ChatMessageRole)));
+        Assert.That(chatCompletion.FunctionCall, Is.Null);
+        Assert.That(chatCompletion.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(chatCompletion.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(chatCompletion.Model, Is.Null);
+        Assert.That(chatCompletion.SystemFingerprint, Is.Null);
+        Assert.That(chatCompletion.Usage, Is.EqualTo(usage));
+    }
+
+    [Test]
+    public void ChatTokenLogProbabilityInfoWithNoPropertiesWorks()
+    {
+        ChatTokenLogProbabilityInfo chatTokenLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenLogProbabilityInfo();
+
+        Assert.That(chatTokenLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+        Assert.That(chatTokenLogProbabilityInfo.TopLogProbabilities, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenLogProbabilityInfoWithTokenWorks()
+    {
+        string token = "a_token_of_appreciation";
+        ChatTokenLogProbabilityInfo chatTokenLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(token: token);
+
+        Assert.That(chatTokenLogProbabilityInfo.Token, Is.EqualTo(token));
+        Assert.That(chatTokenLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+        Assert.That(chatTokenLogProbabilityInfo.TopLogProbabilities, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenLogProbabilityInfoWithLogProbabilityWorks()
+    {
+        float logProbability = 3.14f;
+        ChatTokenLogProbabilityInfo chatTokenLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: logProbability);
+
+        Assert.That(chatTokenLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenLogProbabilityInfo.LogProbability, Is.EqualTo(logProbability));
+        Assert.That(chatTokenLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+        Assert.That(chatTokenLogProbabilityInfo.TopLogProbabilities, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenLogProbabilityInfoWithUtf8ByteValuesWorks()
+    {
+        IEnumerable<int> utf8ByteValues = [104, 101, 108, 108, 111];
+        ChatTokenLogProbabilityInfo chatTokenLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(utf8ByteValues: utf8ByteValues);
+
+        Assert.That(chatTokenLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenLogProbabilityInfo.Utf8ByteValues.SequenceEqual(utf8ByteValues), Is.True);
+        Assert.That(chatTokenLogProbabilityInfo.TopLogProbabilities, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenLogProbabilityInfoWithTopLogProbabilitiesWorks()
+    {
+        IEnumerable<ChatTokenTopLogProbabilityInfo> topLogProbabilities = [
+            OpenAIChatModelFactory.ChatTokenTopLogProbabilityInfo(token: "firstToken"),
+            OpenAIChatModelFactory.ChatTokenTopLogProbabilityInfo(token: "secondToken")
+        ];
+        ChatTokenLogProbabilityInfo chatTokenLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(topLogProbabilities: topLogProbabilities);
+
+        Assert.That(chatTokenLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+        Assert.That(chatTokenLogProbabilityInfo.TopLogProbabilities.SequenceEqual(topLogProbabilities), Is.True);
+    }
+
+    [Test]
+    public void ChatTokenTopLogProbabilityInfoWithNoPropertiesWorks()
+    {
+        ChatTokenTopLogProbabilityInfo chatTokenTopLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenTopLogProbabilityInfo();
+
+        Assert.That(chatTokenTopLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenTopLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenTopLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenTopLogProbabilityInfoWithTokenWorks()
+    {
+        string token = "a_token_of_appreciation";
+        ChatTokenTopLogProbabilityInfo chatTokenTopLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenTopLogProbabilityInfo(token: token);
+
+        Assert.That(chatTokenTopLogProbabilityInfo.Token, Is.EqualTo(token));
+        Assert.That(chatTokenTopLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenTopLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenTopLogProbabilityInfoWithLogProbabilityWorks()
+    {
+        float logProbability = 3.14f;
+        ChatTokenTopLogProbabilityInfo chatTokenTopLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenTopLogProbabilityInfo(logProbability: logProbability);
+
+        Assert.That(chatTokenTopLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenTopLogProbabilityInfo.LogProbability, Is.EqualTo(logProbability));
+        Assert.That(chatTokenTopLogProbabilityInfo.Utf8ByteValues, Is.Not.Null.And.Empty);
+    }
+
+    [Test]
+    public void ChatTokenTopLogProbabilityInfoWithUtf8ByteValuesWorks()
+    {
+        IEnumerable<int> utf8ByteValues = [104, 101, 108, 108, 111];
+        ChatTokenTopLogProbabilityInfo chatTokenTopLogProbabilityInfo = OpenAIChatModelFactory.ChatTokenTopLogProbabilityInfo(utf8ByteValues: utf8ByteValues);
+
+        Assert.That(chatTokenTopLogProbabilityInfo.Token, Is.Null);
+        Assert.That(chatTokenTopLogProbabilityInfo.LogProbability, Is.EqualTo(0f));
+        Assert.That(chatTokenTopLogProbabilityInfo.Utf8ByteValues.SequenceEqual(utf8ByteValues), Is.True);
+    }
+
+    [Test]
+    public void ChatTokenUsageWithNoPropertiesWorks()
+    {
+        ChatTokenUsage chatTokenUsage = OpenAIChatModelFactory.ChatTokenUsage();
+
+        Assert.That(chatTokenUsage.OutputTokens, Is.EqualTo(0));
+        Assert.That(chatTokenUsage.InputTokens, Is.EqualTo(0));
+        Assert.That(chatTokenUsage.TotalTokens, Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ChatTokenUsageWithOutputTokensWorks()
+    {
+        int outputTokens = 271828;
+        ChatTokenUsage chatTokenUsage = OpenAIChatModelFactory.ChatTokenUsage(outputTokens: outputTokens);
+
+        Assert.That(chatTokenUsage.OutputTokens, Is.EqualTo(outputTokens));
+        Assert.That(chatTokenUsage.InputTokens, Is.EqualTo(0));
+        Assert.That(chatTokenUsage.TotalTokens, Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ChatTokenUsageWithInputTokensWorks()
+    {
+        int inputTokens = 271828;
+        ChatTokenUsage chatTokenUsage = OpenAIChatModelFactory.ChatTokenUsage(inputTokens: inputTokens);
+
+        Assert.That(chatTokenUsage.OutputTokens, Is.EqualTo(0));
+        Assert.That(chatTokenUsage.InputTokens, Is.EqualTo(inputTokens));
+        Assert.That(chatTokenUsage.TotalTokens, Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ChatTokenUsageWithTotalTokensWorks()
+    {
+        int totalTokens = 271828;
+        ChatTokenUsage chatTokenUsage = OpenAIChatModelFactory.ChatTokenUsage(totalTokens: totalTokens);
+
+        Assert.That(chatTokenUsage.OutputTokens, Is.EqualTo(0));
+        Assert.That(chatTokenUsage.InputTokens, Is.EqualTo(0));
+        Assert.That(chatTokenUsage.TotalTokens, Is.EqualTo(totalTokens));
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithNoPropertiesWorks()
+    {
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate();
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithIdWorks()
+    {
+        string id = "chat_completion_id";
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(id: id);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.EqualTo(id));
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithContentUpdateWorks()
+    {
+        IEnumerable<ChatMessageContentPart> contentUpdate = [
+            ChatMessageContentPart.CreateTextMessageContentPart("first part"),
+            ChatMessageContentPart.CreateTextMessageContentPart("second part")
+        ];
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(contentUpdate: contentUpdate);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate.SequenceEqual(contentUpdate), Is.True);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithFunctionCallUpdateWorks()
+    {
+        StreamingChatFunctionCallUpdate functionCallUpdate = OpenAIChatModelFactory.StreamingChatFunctionCallUpdate(functionName: "get_recipte");
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(functionCallUpdate: functionCallUpdate);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.EqualTo(functionCallUpdate));
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithToolCallUpdatesWorks()
+    {
+        IEnumerable<StreamingChatToolCallUpdate> toolCallUpdates = [
+            OpenAIChatModelFactory.StreamingChatToolCallUpdate(id: "id1"),
+            OpenAIChatModelFactory.StreamingChatToolCallUpdate(id: "id2")
+        ];
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(toolCallUpdates: toolCallUpdates);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates.SequenceEqual(toolCallUpdates), Is.True);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithRoleWorks()
+    {
+        ChatMessageRole role = ChatMessageRole.Tool;
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(role: role);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.EqualTo(role));
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithRefusalUpdateWorks()
+    {
+        string refusalUpdate = "This is a refusal update.";
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(refusalUpdate: refusalUpdate);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.EqualTo(refusalUpdate));
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithContentTokenLogProbabilitiesWorks()
+    {
+        IEnumerable<ChatTokenLogProbabilityInfo> contentTokenLogProbabilities = [
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 1f),
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 2f)
+        ];
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(contentTokenLogProbabilities: contentTokenLogProbabilities);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities.SequenceEqual(contentTokenLogProbabilities), Is.True);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithRefusalTokenLogProbabilitiesWorks()
+    {
+        IEnumerable<ChatTokenLogProbabilityInfo> refusalTokenLogProbabilities = [
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 1f),
+            OpenAIChatModelFactory.ChatTokenLogProbabilityInfo(logProbability: 2f)
+        ];
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(refusalTokenLogProbabilities: refusalTokenLogProbabilities);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities.SequenceEqual(refusalTokenLogProbabilities), Is.True);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithFinishReasonWorks()
+    {
+        ChatFinishReason finishReason = ChatFinishReason.ToolCalls;
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(finishReason: finishReason);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.EqualTo(finishReason));
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithCreatedAtWorks()
+    {
+        DateTimeOffset createdAt = DateTimeOffset.UtcNow;
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(createdAt: createdAt);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(createdAt));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithModelWorks()
+    {
+        string model = "topmodel";
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(model: model);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.EqualTo(model));
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithSystemFingerprintWorks()
+    {
+        string systemFingerprint = "footprint";
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(systemFingerprint: systemFingerprint);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.EqualTo(systemFingerprint));
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatCompletionUpdateWithUsageWorks()
+    {
+        ChatTokenUsage usage = OpenAIChatModelFactory.ChatTokenUsage(outputTokens: 20);
+        StreamingChatCompletionUpdate streamingChatCompletionUpdate = OpenAIChatModelFactory.StreamingChatCompletionUpdate(usage: usage);
+
+        Assert.That(streamingChatCompletionUpdate.Id, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentUpdate, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FunctionCallUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ToolCallUpdates, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.Role, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.RefusalUpdate, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.ContentTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.RefusalTokenLogProbabilities, Is.Not.Null.And.Empty);
+        Assert.That(streamingChatCompletionUpdate.FinishReason, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.CreatedAt, Is.EqualTo(default(DateTimeOffset)));
+        Assert.That(streamingChatCompletionUpdate.Model, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.SystemFingerprint, Is.Null);
+        Assert.That(streamingChatCompletionUpdate.Usage, Is.EqualTo(usage));
+    }
+
+    [Test]
+    public void StreamingChatFunctionCallUpdateWithNoPropertiesWorks()
+    {
+        StreamingChatFunctionCallUpdate streamingChatFunctionCallUpdate = OpenAIChatModelFactory.StreamingChatFunctionCallUpdate();
+
+        Assert.That(streamingChatFunctionCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatFunctionCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatFunctionCallUpdateWithFunctionNameWorks()
+    {
+        string functionName = "Margaret";
+        StreamingChatFunctionCallUpdate streamingChatFunctionCallUpdate = OpenAIChatModelFactory.StreamingChatFunctionCallUpdate(functionName: functionName);
+
+        Assert.That(streamingChatFunctionCallUpdate.FunctionName, Is.EqualTo(functionName));
+        Assert.That(streamingChatFunctionCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatFunctionCallUpdateWithFunctionArgumentsUpdateWorks()
+    {
+        string functionArgumentsUpdate = "arguments_update";
+        StreamingChatFunctionCallUpdate streamingChatFunctionCallUpdate = OpenAIChatModelFactory.StreamingChatFunctionCallUpdate(functionArgumentsUpdate: functionArgumentsUpdate);
+
+        Assert.That(streamingChatFunctionCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatFunctionCallUpdate.FunctionArgumentsUpdate, Is.EqualTo(functionArgumentsUpdate));
+    }
+
+    [Test]
+    public void StreamingChatToolCallUpdateWithNoPropertiesWorks()
+    {
+        StreamingChatToolCallUpdate streamingChatToolCallUpdate = OpenAIChatModelFactory.StreamingChatToolCallUpdate();
+
+        Assert.That(streamingChatToolCallUpdate.Index, Is.EqualTo(0));
+        Assert.That(streamingChatToolCallUpdate.Id, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.Kind, Is.EqualTo(default(ChatToolCallKind)));
+        Assert.That(streamingChatToolCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatToolCallUpdateWithIndexWorks()
+    {
+        int index = 31415;
+        StreamingChatToolCallUpdate streamingChatToolCallUpdate = OpenAIChatModelFactory.StreamingChatToolCallUpdate(index: index);
+
+        Assert.That(streamingChatToolCallUpdate.Index, Is.EqualTo(index));
+        Assert.That(streamingChatToolCallUpdate.Id, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.Kind, Is.EqualTo(default(ChatToolCallKind)));
+        Assert.That(streamingChatToolCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatToolCallUpdateWithIdWorks()
+    {
+        string id = "tool_call_id";
+        StreamingChatToolCallUpdate streamingChatToolCallUpdate = OpenAIChatModelFactory.StreamingChatToolCallUpdate(id: id);
+
+        Assert.That(streamingChatToolCallUpdate.Index, Is.EqualTo(0));
+        Assert.That(streamingChatToolCallUpdate.Id, Is.EqualTo(id));
+        Assert.That(streamingChatToolCallUpdate.Kind, Is.EqualTo(default(ChatToolCallKind)));
+        Assert.That(streamingChatToolCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatToolCallUpdateWithKindWorks()
+    {
+        ChatToolCallKind kind = ChatToolCallKind.Function;
+        StreamingChatToolCallUpdate streamingChatToolCallUpdate = OpenAIChatModelFactory.StreamingChatToolCallUpdate(kind: kind);
+
+        Assert.That(streamingChatToolCallUpdate.Index, Is.EqualTo(0));
+        Assert.That(streamingChatToolCallUpdate.Id, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.Kind, Is.EqualTo(kind));
+        Assert.That(streamingChatToolCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatToolCallUpdateWithFunctionNameWorks()
+    {
+        string functionName = "Margaret";
+        StreamingChatToolCallUpdate streamingChatToolCallUpdate = OpenAIChatModelFactory.StreamingChatToolCallUpdate(functionName: functionName);
+
+        Assert.That(streamingChatToolCallUpdate.Index, Is.EqualTo(0));
+        Assert.That(streamingChatToolCallUpdate.Id, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.Kind, Is.EqualTo(default(ChatToolCallKind)));
+        Assert.That(streamingChatToolCallUpdate.FunctionName, Is.EqualTo(functionName));
+        Assert.That(streamingChatToolCallUpdate.FunctionArgumentsUpdate, Is.Null);
+    }
+
+    [Test]
+    public void StreamingChatToolCallUpdateWithFunctionArgumentsUpdateWorks()
+    {
+        string functionArgumentsUpdate = "arguments_update";
+        StreamingChatToolCallUpdate streamingChatToolCallUpdate = OpenAIChatModelFactory.StreamingChatToolCallUpdate(functionArgumentsUpdate: functionArgumentsUpdate);
+
+        Assert.That(streamingChatToolCallUpdate.Index, Is.EqualTo(0));
+        Assert.That(streamingChatToolCallUpdate.Id, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.Kind, Is.EqualTo(default(ChatToolCallKind)));
+        Assert.That(streamingChatToolCallUpdate.FunctionName, Is.Null);
+        Assert.That(streamingChatToolCallUpdate.FunctionArgumentsUpdate, Is.EqualTo(functionArgumentsUpdate));
+    }
+}