.Net: Gemini - Removed limitation when gemini throws exception if invalid response (BREAKING CHANGE)

dotnet/src/Connectors/Connectors.Google.UnitTests/Core/Gemini/Clients/GeminiChatGenerationTests.cs

@@ -33,6 +33,24 @@ public GeminiChatGenerationTests()
         this._httpClient = new HttpClient(this._messageHandlerStub, false);
     }
 
+    [Fact]
+    public async Task ShouldReturnEmptyMessageContentAndNullMetadataIfEmptyJsonInResponseAsync()
+    {
+        // Arrange
+        this._messageHandlerStub.ResponseToReturn.Content = new StringContent("{}");
+        var client = this.CreateChatCompletionClient();
+        var chatHistory = CreateSampleChatHistory();
+
+        // Act
+        var messages = await client.GenerateChatMessageAsync(chatHistory);
+
+        // Assert
+        Assert.Single(messages, item =>
+            item.Role == AuthorRole.Assistant &&
+            string.IsNullOrEmpty(item.Content) &&
+            item.Metadata == null);
+    }
+
     [Fact]
     public async Task ShouldReturnEmptyMessageContentIfNoContentInResponseAsync()
     {
@@ -417,12 +435,12 @@ public async Task ItCanUseValueTasksSequentiallyForBearerTokenAsync()
         using var httpClient = new HttpClient(multipleMessageHandlerStub, false);
 
         var client = new GeminiChatCompletionClient(
-                httpClient: httpClient,
-                modelId: "fake-model",
-                apiVersion: VertexAIVersion.V1,
-                bearerTokenProvider: () => bearerTokenGenerator.GetBearerToken(),
-                location: "fake-location",
-                projectId: "fake-project-id");
+            httpClient: httpClient,
+            modelId: "fake-model",
+            apiVersion: VertexAIVersion.V1,
+            bearerTokenProvider: () => bearerTokenGenerator.GetBearerToken(),
+            location: "fake-location",
+            projectId: "fake-project-id");
 
         var chatHistory = CreateSampleChatHistory();
 

dotnet/src/Connectors/Connectors.Google.UnitTests/Core/Gemini/Clients/GeminiChatStreamingTests.cs

@@ -33,6 +33,24 @@ public GeminiChatStreamingTests()
         this._httpClient = new HttpClient(this._messageHandlerStub, false);
     }
 
+    [Fact]
+    public async Task ShouldReturnEmptyMessageContentAndNullMetadataIfEmptyJsonInResponseAsync()
+    {
+        // Arrange
+        this._messageHandlerStub.ResponseToReturn.Content = new StringContent("{}");
+        var client = this.CreateChatCompletionClient();
+        var chatHistory = CreateSampleChatHistory();
+
+        // Act
+        var messages = await client.StreamGenerateChatMessageAsync(chatHistory).ToListAsync();
+
+        // Assert
+        Assert.Single(messages, item =>
+            item.Role == AuthorRole.Assistant &&
+            string.IsNullOrEmpty(item.Content) &&
+            item.Metadata == null);
+    }
+
     [Fact]
     public async Task ShouldReturnEmptyMessageContentIfNoContentInResponseAsync()
     {

dotnet/src/Connectors/Connectors.Google/Core/Gemini/Clients/GeminiChatCompletionClient.cs

@@ -559,15 +559,10 @@ private List<GeminiChatMessageContent> ProcessChatResponse(GeminiResponse gemini
 
     private static void ValidateGeminiResponse(GeminiResponse geminiResponse)
     {
-        if (geminiResponse.Candidates is null || geminiResponse.Candidates.Count == 0)
+        if (geminiResponse.PromptFeedback?.BlockReason is not null)
         {
-            if (geminiResponse.PromptFeedback?.BlockReason is not null)
-            {
-                // TODO: Currently SK doesn't support prompt feedback/finish status, so we just throw an exception. I told SK team that we need to support it: https://github.com/microsoft/semantic-kernel/issues/4621
-                throw new KernelException("Prompt was blocked due to Gemini API safety reasons.");
-            }
-
-            throw new KernelException("Gemini API doesn't return any data.");
+            // TODO: Currently SK doesn't support prompt feedback/finish status, so we just throw an exception. I told SK team that we need to support it: https://github.com/microsoft/semantic-kernel/issues/4621
+            throw new KernelException("Prompt was blocked due to Gemini API safety reasons.");
         }
     }
 
@@ -596,7 +591,9 @@ private void LogUsage(List<GeminiChatMessageContent> chatMessageContents)
     }
 
     private List<GeminiChatMessageContent> GetChatMessageContentsFromResponse(GeminiResponse geminiResponse)
-        => geminiResponse.Candidates!.Select(candidate => this.GetChatMessageContentFromCandidate(geminiResponse, candidate)).ToList();
+        => geminiResponse.Candidates == null ?
+            [new GeminiChatMessageContent(role: AuthorRole.Assistant, content: string.Empty, modelId: this._modelId)]
+            : geminiResponse.Candidates.Select(candidate => this.GetChatMessageContentFromCandidate(geminiResponse, candidate)).ToList();
 
     private GeminiChatMessageContent GetChatMessageContentFromCandidate(GeminiResponse geminiResponse, GeminiResponseCandidate candidate)
     {
@@ -630,7 +627,7 @@ private GeminiStreamingChatMessageContent GetStreamingChatContentFromChatContent
                 modelId: this._modelId,
                 calledToolResult: message.CalledToolResult,
                 metadata: message.Metadata,
-                choiceIndex: message.Metadata!.Index);
+                choiceIndex: message.Metadata?.Index ?? 0);
         }
 
         if (message.ToolCalls is not null)
@@ -641,14 +638,14 @@ private GeminiStreamingChatMessageContent GetStreamingChatContentFromChatContent
                 modelId: this._modelId,
                 toolCalls: message.ToolCalls,
                 metadata: message.Metadata,
-                choiceIndex: message.Metadata!.Index);
+                choiceIndex: message.Metadata?.Index ?? 0);
         }
 
         return new GeminiStreamingChatMessageContent(
             role: message.Role,
             content: message.Content,
             modelId: this._modelId,
-            choiceIndex: message.Metadata!.Index,
+            choiceIndex: message.Metadata?.Index ?? 0,
             metadata: message.Metadata);
     }