fix: GenAI - Capture content blocked case when validating responses

PiperOrigin-RevId: 616988650

tests/unit/vertexai/test_generative_models.py

@@ -133,6 +133,20 @@ def mock_generate_content(
         )
         return response
 
+    should_block = (
+        last_message_part.text
+        and "Please block with block_reason=OTHER" in last_message_part.text
+    )
+    if should_block:
+        response = gapic_prediction_service_types.GenerateContentResponse(
+            candidates=[],
+            prompt_feedback=gapic_prediction_service_types.GenerateContentResponse.PromptFeedback(
+                block_reason=gapic_prediction_service_types.GenerateContentResponse.PromptFeedback.BlockedReason.OTHER,
+                block_reason_message="Blocked for testing",
+            ),
+        )
+        return response
+
     is_continued_chat = len(request.contents) > 1
     has_retrieval = any(
         tool.retrieval or tool.google_search_retrieval for tool in request.tools
@@ -349,6 +363,31 @@ def test_chat_send_message_response_validation_errors(
         # Checking that history did not get updated
         assert len(chat.history) == 2
 
+    @mock.patch.object(
+        target=prediction_service.PredictionServiceClient,
+        attribute="generate_content",
+        new=mock_generate_content,
+    )
+    @pytest.mark.parametrize(
+        "generative_models",
+        [generative_models, preview_generative_models],
+    )
+    def test_chat_send_message_response_blocked_errors(
+        self, generative_models: generative_models
+    ):
+        model = generative_models.GenerativeModel("gemini-pro")
+        chat = model.start_chat()
+        response1 = chat.send_message("Why is sky blue?")
+        assert response1.text
+        assert len(chat.history) == 2
+
+        with pytest.raises(generative_models.ResponseValidationError) as e:
+            chat.send_message("Please block with block_reason=OTHER.")
+
+        assert e.match("Blocked for testing")
+        # Checking that history did not get updated
+        assert len(chat.history) == 2
+
     @mock.patch.object(
         target=prediction_service.PredictionServiceClient,
         attribute="generate_content",

vertexai/generative_models/_generative_models.py

@@ -640,13 +640,23 @@ def _validate_response(
     request_contents: Optional[List["Content"]] = None,
     response_chunks: Optional[List["GenerationResponse"]] = None,
 ) -> None:
-    candidate = response.candidates[0]
-    if candidate.finish_reason not in _SUCCESSFUL_FINISH_REASONS:
-        message = (
-            "The model response did not completed successfully.\n"
-            f"Finish reason: {candidate.finish_reason}.\n"
-            f"Finish message: {candidate.finish_message}.\n"
-            f"Safety ratings: {candidate.safety_ratings}.\n"
+    message = ""
+    if not response.candidates:
+        message += (
+            f"The model response was blocked due to {response._raw_response.prompt_feedback.block_reason}.\n"
+            f"Blocke reason message: {response._raw_response.prompt_feedback.block_reason_message}.\n"
+        )
+    else:
+        candidate = response.candidates[0]
+        if candidate.finish_reason not in _SUCCESSFUL_FINISH_REASONS:
+            message = (
+                "The model response did not completed successfully.\n"
+                f"Finish reason: {candidate.finish_reason}.\n"
+                f"Finish message: {candidate.finish_message}.\n"
+                f"Safety ratings: {candidate.safety_ratings}.\n"
+            )
+    if message:
+        message += (
             "To protect the integrity of the chat session, the request and response were not added to chat history.\n"
             "To skip the response validation, specify `model.start_chat(response_validation=False)`.\n"
             "Note that letting blocked or otherwise incomplete responses into chat history might lead to future interactions being blocked by the service."