types: enable passing messages with arbitrary role (#462)

---------

Co-authored-by: Ryan Stewart <ryanstewart@Ryans-MacBook-Pro.local>
Co-authored-by: Gabe Goodhart <gabe.l.hart@gmail.com>

ollama/_types.py

@@ -256,7 +256,7 @@ class Message(SubscriptableBaseModel):
   Chat message.
   """
 
-  role: Literal['user', 'assistant', 'system', 'tool']
+  role: str
   "Assumed role of the message. Response messages has role 'assistant' or 'tool'."
 
   content: Optional[str] = None

tests/test_client.py

@@ -4,14 +4,16 @@ import os
 import re
 import tempfile
 from pathlib import Path
+from typing import Any
 
 import pytest
+from httpx import Response as httpxResponse
 from pydantic import BaseModel, ValidationError
 from pytest_httpserver import HTTPServer, URIPattern
 from werkzeug.wrappers import Request, Response
 
 from ollama._client import CONNECTION_ERROR_MESSAGE, AsyncClient, Client, _copy_tools
-from ollama._types import Image
+from ollama._types import Image, Message
 
 PNG_BASE64 = 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAADElEQVR4nGNgYGAAAAAEAAH2FzhVAAAAAElFTkSuQmCC'
 PNG_BYTES = base64.b64decode(PNG_BASE64)
@@ -1181,3 +1183,32 @@ async def test_async_client_connection_error():
   with pytest.raises(ConnectionError) as exc_info:
     await client.show('model')
   assert str(exc_info.value) == 'Failed to connect to Ollama. Please check that Ollama is downloaded, running and accessible. https://ollama.com/download'
+
+
+def test_arbitrary_roles_accepted_in_message():
+  _ = Message(role='somerandomrole', content="I'm ok with you adding any role message now!")
+
+
+def _mock_request(*args: Any, **kwargs: Any) -> Response:
+  return httpxResponse(status_code=200, content="{'response': 'Hello world!'}")
+
+
+def test_arbitrary_roles_accepted_in_message_request(monkeypatch: pytest.MonkeyPatch):
+  monkeypatch.setattr(Client, '_request', _mock_request)
+
+  client = Client()
+
+  client.chat(model='llama3.1', messages=[{'role': 'somerandomrole', 'content': "I'm ok with you adding any role message now!"}, {'role': 'user', 'content': 'Hello world!'}])
+
+
+async def _mock_request_async(*args: Any, **kwargs: Any) -> Response:
+  return httpxResponse(status_code=200, content="{'response': 'Hello world!'}")
+
+
+@pytest.mark.asyncio
+async def test_arbitrary_roles_accepted_in_message_request_async(monkeypatch: pytest.MonkeyPatch):
+  monkeypatch.setattr(AsyncClient, '_request', _mock_request_async)
+
+  client = AsyncClient()
+
+  await client.chat(model='llama3.1', messages=[{'role': 'somerandomrole', 'content': "I'm ok with you adding any role message now!"}, {'role': 'user', 'content': 'Hello world!'}])