fix(main.py): fix openai message for assistant msg if role is missing - openai allows this

Fixes https://github.com/BerriAI/litellm/issues/8661

litellm/main.py

@@ -94,7 +94,7 @@ from litellm.utils import (
     read_config_args,
     supports_httpx_timeout,
     token_counter,
-    validate_chat_completion_messages,
+    validate_and_fix_openai_messages,
     validate_chat_completion_tool_choice,
 )
 
@@ -851,7 +851,7 @@ def completion(  # type: ignore # noqa: PLR0915
     if model is None:
         raise ValueError("model param not passed in.")
     # validate messages
-    messages = validate_chat_completion_messages(messages=messages)
+    messages = validate_and_fix_openai_messages(messages=messages)
     # validate tool_choice
     tool_choice = validate_chat_completion_tool_choice(tool_choice=tool_choice)
     ######### unpacking kwargs #####################

litellm/utils.py

@@ -5932,6 +5932,18 @@ def convert_to_dict(message: Union[BaseModel, dict]) -> dict:
         )
 
 
+def validate_and_fix_openai_messages(messages: List):
+    """
+    Ensures all messages are valid OpenAI chat completion messages.
+
+    Handles missing role for assistant messages.
+    """
+    for message in messages:
+        if "role" not in message:
+            message["role"] = "assistant"
+    return validate_chat_completion_messages(messages=messages)
+
+
 def validate_chat_completion_messages(messages: List[AllMessageValues]):
     """
     Ensures all messages are valid OpenAI chat completion messages.
@@ -6282,11 +6294,18 @@ def get_end_user_id_for_cost_tracking(
         return None
     return end_user_id
 
-def should_use_cohere_v1_client(api_base: Optional[str], present_version_params: List[str]):
+
+def should_use_cohere_v1_client(
+    api_base: Optional[str], present_version_params: List[str]
+):
     if not api_base:
         return False
-    uses_v1_params = ("max_chunks_per_doc" in present_version_params) and ('max_tokens_per_doc' not in present_version_params) 
-    return api_base.endswith("/v1/rerank") or (uses_v1_params and not api_base.endswith("/v2/rerank"))
+    uses_v1_params = ("max_chunks_per_doc" in present_version_params) and (
+        "max_tokens_per_doc" not in present_version_params
+    )
+    return api_base.endswith("/v1/rerank") or (
+        uses_v1_params and not api_base.endswith("/v2/rerank")
+    )
 
 
 def is_prompt_caching_valid_prompt(

tests/litellm/test_main.py

@@ -0,0 +1,119 @@
+import json
+import os
+import sys
+
+import pytest
+from fastapi.testclient import TestClient
+
+sys.path.insert(
+    0, os.path.abspath("../..")
+)  # Adds the parent directory to the system path
+
+from unittest.mock import MagicMock, patch
+
+import litellm
+
+
+@pytest.fixture
+def openai_api_response():
+    mock_response_data = {
+        "id": "chatcmpl-B0W3vmiM78Xkgx7kI7dr7PC949DMS",
+        "choices": [
+            {
+                "finish_reason": "stop",
+                "index": 0,
+                "logprobs": None,
+                "message": {
+                    "content": "",
+                    "refusal": None,
+                    "role": "assistant",
+                    "audio": None,
+                    "function_call": None,
+                    "tool_calls": None,
+                },
+            }
+        ],
+        "created": 1739462947,
+        "model": "gpt-4o-mini-2024-07-18",
+        "object": "chat.completion",
+        "service_tier": "default",
+        "system_fingerprint": "fp_bd83329f63",
+        "usage": {
+            "completion_tokens": 1,
+            "prompt_tokens": 121,
+            "total_tokens": 122,
+            "completion_tokens_details": {
+                "accepted_prediction_tokens": 0,
+                "audio_tokens": 0,
+                "reasoning_tokens": 0,
+                "rejected_prediction_tokens": 0,
+            },
+            "prompt_tokens_details": {"audio_tokens": 0, "cached_tokens": 0},
+        },
+    }
+
+    return mock_response_data
+
+
+def test_completion_missing_role(openai_api_response):
+    from openai import OpenAI
+
+    from litellm.types.utils import ModelResponse
+
+    client = OpenAI(api_key="test_api_key")
+
+    mock_raw_response = MagicMock()
+    mock_raw_response.headers = {
+        "x-request-id": "123",
+        "openai-organization": "org-123",
+        "x-ratelimit-limit-requests": "100",
+        "x-ratelimit-remaining-requests": "99",
+    }
+    mock_raw_response.parse.return_value = ModelResponse(**openai_api_response)
+
+    print(f"openai_api_response: {openai_api_response}")
+
+    with patch.object(
+        client.chat.completions.with_raw_response, "create", mock_raw_response
+    ) as mock_create:
+        litellm.completion(
+            model="gpt-4o-mini",
+            messages=[
+                {"role": "user", "content": "Hey"},
+                {
+                    "content": "",
+                    "tool_calls": [
+                        {
+                            "id": "call_m0vFJjQmTH1McvaHBPR2YFwY",
+                            "function": {
+                                "arguments": '{"input": "dksjsdkjdhskdjshdskhjkhlk"}',
+                                "name": "tool_name",
+                            },
+                            "type": "function",
+                            "index": 0,
+                        },
+                        {
+                            "id": "call_Vw6RaqV2n5aaANXEdp5pYxo2",
+                            "function": {
+                                "arguments": '{"input": "jkljlkjlkjlkjlk"}',
+                                "name": "tool_name",
+                            },
+                            "type": "function",
+                            "index": 1,
+                        },
+                        {
+                            "id": "call_hBIKwldUEGlNh6NlSXil62K4",
+                            "function": {
+                                "arguments": '{"input": "jkjlkjlkjlkj;lj"}',
+                                "name": "tool_name",
+                            },
+                            "type": "function",
+                            "index": 2,
+                        },
+                    ],
+                },
+            ],
+            client=client,
+        )
+
+        mock_create.assert_called_once()