fix StreamChatAsync and make an unit and integration test for it

SpongeEngine.LMStudioSharp.Tests/Integration/IntegrationTests.cs

@@ -5,6 +5,8 @@
 using SpongeEngine.LMStudioSharp.Models.Chat;
 using SpongeEngine.LMStudioSharp.Models.Completion;
 using SpongeEngine.LMStudioSharp.Tests.Common;
+using WireMock.RequestBuilders;
+using WireMock.ResponseBuilders;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -31,6 +33,39 @@ public IntegrationTests(ITestOutputHelper output) : base(output)
                     .CreateLogger(GetType()),
             });
         }
+
+        [SkippableFact]
+        [Trait("Category", "Integration")]
+        public async Task StreamChatAsync_WithDeltaProperty_ShouldStreamTokens()
+        {
+            // Arrange: Create a chat request with streaming enabled.
+            var request = new ChatRequest
+            {
+                Model = "test-model",  // Use your model ID if available.
+                Temperature = 0.7f,
+                Stream = true
+            };
+            request.Messages.Add(new ChatMessage { Role = "user", Content = "Hello" });
+
+            // Act: Consume the streaming response from the LM Studio server.
+            var receivedTokens = new List<string>();
+            await foreach (var token in Client.StreamChatAsync(request))
+            {
+                receivedTokens.Add(token);
+                Output.WriteLine($"Received token: {token}");
+            }
+
+            // If no tokens were received, we skip the test
+            // (for example, if the LM Studio server isn’t returning streaming tokens yet).
+            if (receivedTokens.Count == 0)
+            {
+                throw new SkipException("LM Studio server did not return any streaming tokens. " +
+                                        "Ensure that streaming chat responses are enabled and use the delta format.");
+            }
+
+            // Assert: Verify that some tokens were streamed.
+            receivedTokens.Should().NotBeEmpty("the LM Studio server should stream tokens for chat requests using the delta property");
+        }
 
         [SkippableFact]
         [Trait("Category", "Integration")]

SpongeEngine.LMStudioSharp.Tests/SpongeEngine.LMStudioSharp.Tests.csproj

@@ -4,7 +4,7 @@
         <Nullable>enable</Nullable>
         <IsPackable>false</IsPackable>
         <TargetFrameworks>net8.0;net6.0;net7.0</TargetFrameworks>
-        <Version>0.3.9.1</Version>
+        <Version>0.3.9.2</Version>
     </PropertyGroup>
 
     <ItemGroup>

SpongeEngine.LMStudioSharp.Tests/Unit/UnitTests.cs

@@ -33,6 +33,48 @@ public UnitTests(ITestOutputHelper output) : base(output)
                     .CreateLogger(GetType()),
             });
         }
+
+        [Fact]
+        public async Task StreamChatAsync_WithDeltaProperty_ShouldStreamTokens_Unit()
+        {
+            // Arrange: Create a chat request with streaming enabled.
+            var request = new ChatRequest
+            {
+                Model = "test-model",
+                Messages = new List<ChatMessage>
+                {
+                    new() { Role = "user", Content = "Hello" }
+                },
+                Temperature = 0.7f,
+                Stream = true
+            };
+
+            // Define the tokens that should be returned by the stream.
+            var tokens = new[] { "Hello", " there", "!" };
+
+            // Create simulated SSE responses using the "delta" property.
+            var streamResponses = tokens.Select(token => $"data: {{\"choices\": [{{\"delta\": {{\"content\": \"{token}\"}}}}]}}\n\n");
+
+            // Configure WireMock to simulate the chat completions endpoint with delta-based tokens.
+            Server
+                .Given(Request.Create()
+                    .WithPath("/api/v0/chat/completions")
+                    .UsingPost())
+                .RespondWith(Response.Create()
+                    .WithStatusCode(200)
+                    .WithBody(string.Join("", streamResponses) + "data: [DONE]\n\n")
+                    .WithHeader("Content-Type", "text/event-stream"));
+
+            // Act: Consume the streaming response.
+            var receivedTokens = new List<string>();
+            await foreach (var token in Client.StreamChatAsync(request))
+            {
+                receivedTokens.Add(token);
+            }
+
+            // Assert: Verify that the tokens received match the expected tokens.
+            receivedTokens.Should().BeEquivalentTo(tokens);
+        }
 
         [Fact]
         public async Task ListModelsAsync_ShouldReturnModels()

SpongeEngine.LMStudioSharp/LMStudioSharpClient.cs

@@ -230,7 +230,8 @@ private async IAsyncEnumerable<string> StreamResponseAsync<T>(string endpoint, T
                 try
                 {
                     var streamResponse = JsonSerializer.Deserialize<StreamResponse>(data, Options.JsonSerializerOptions);
-                    token = streamResponse?.Choices?.FirstOrDefault()?.Text;
+                    var choice = streamResponse?.Choices?.FirstOrDefault();
+                    token = choice?.Text ?? choice?.Delta?.Content;
                 }
                 catch (JsonException ex)
                 {
@@ -253,12 +254,23 @@ private class StreamResponse
 
             public class StreamChoice
             {
+                // For plain text completions:
                 [JsonPropertyName("text")]
-                public string Text { get; set; } = string.Empty;
+                public string? Text { get; set; }
+
+                // For chat completions:
+                [JsonPropertyName("delta")]
+                public Delta? Delta { get; set; }
 
                 [JsonPropertyName("finish_reason")]
                 public string? FinishReason { get; set; }
             }
+
+            public class Delta
+            {
+                [JsonPropertyName("content")]
+                public string? Content { get; set; }
+            }
         }
 
         public async Task<TextCompletionResult> CompleteTextAsync(TextCompletionRequest request, CancellationToken cancellationToken = new CancellationToken())

SpongeEngine.LMStudioSharp/SpongeEngine.LMStudioSharp.csproj

@@ -8,7 +8,7 @@
         <!-- Package Info -->
         <PackageId>SpongeEngine.LMStudioSharp</PackageId>
         <Title>LMStudioSharp</Title>
-        <Version>0.3.9.1</Version>
+        <Version>0.3.9.2</Version>
         <Authors>Dan Clipca</Authors>
         <Company>Sponge Engine</Company>
         <Description>C# client for LM Studio native API.</Description>