vllm/tests/entrypoints/openai/test_completion_with_function_calling.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

import datetime
from typing import Union

import openai  # use the official client for correctness check
import pytest
import pytest_asyncio

# downloading lora to test lora requests
from ...utils import RemoteOpenAIServer

# any model with a chat template should work here
MODEL_NAME = "Qwen/Qwen3-0.6B"

tools = [
    {
        "type": "function",
        "function": {
            "name": "get_current_weather",
            "description": "Get the current weather in a given location",
            "parameters": {
                "type": "object",
                "properties": {
                    "city": {
                        "type": "string",
                        "description":
                        "The city to find the weather for, e.g. 'Vienna'",
                        "default": "Vienna",
                    },
                    "country": {
                        "type":
                        "string",
                        "description":
                        "The country that the city is in, e.g. 'Austria'",
                    },
                    "unit": {
                        "type": "string",
                        "description": "The unit to fetch the temperature in",
                        "enum": ["celsius", "fahrenheit"],
                    },
                    "options": {
                        "$ref": "#/$defs/WeatherOptions",
                        "description": "Optional parameters for weather query",
                    },
                },
                "required": ["country", "unit"],
                "$defs": {
                    "WeatherOptions": {
                        "title": "WeatherOptions",
                        "type": "object",
                        "additionalProperties": False,
                        "properties": {
                            "unit": {
                                "type": "string",
                                "enum": ["celsius", "fahrenheit"],
                                "default": "celsius",
                                "description": "Temperature unit",
                                "title": "Temperature Unit",
                            },
                            "include_forecast": {
                                "type": "boolean",
                                "default": False,
                                "description":
                                "Whether to include a 24-hour forecast",
                                "title": "Include Forecast",
                            },
                            "language": {
                                "type": "string",
                                "default": "zh-CN",
                                "description": "Language of the response",
                                "title": "Language",
                                "enum": ["zh-CN", "en-US", "ja-JP"],
                            },
                        },
                    },
                },
            },
        },
    },
    {
        "type": "function",
        "function": {
            "name": "get_forecast",
            "description": "Get the weather forecast for a given location",
            "parameters": {
                "type": "object",
                "properties": {
                    "city": {
                        "type": "string",
                        "description":
                        "The city to get the forecast for, e.g. 'Vienna'",
                        "default": "Vienna",
                    },
                    "country": {
                        "type":
                        "string",
                        "description":
                        "The country that the city is in, e.g. 'Austria'",
                    },
                    "days": {
                        "type":
                        "integer",
                        "description":
                        "Number of days to get the forecast for (1-7)",
                    },
                    "unit": {
                        "type": "string",
                        "description": "The unit to fetch the temperature in",
                        "enum": ["celsius", "fahrenheit"],
                    },
                },
                "required": ["country", "days", "unit"],
            },
        },
    },
]

messages = [
    {
        "role": "user",
        "content": "Hi! How are you doing today?"
    },
    {
        "role": "assistant",
        "content": "I'm doing well! How can I help you?"
    },
    {
        "role":
        "user",
        "content":
        "Can you tell me what the current weather is in Berlin and the "\
        "forecast for the next 5 days, in fahrenheit?",
    },
]


@pytest.fixture(scope="module")
def server():  # noqa: F811
    args = [
        # use half precision for speed and memory savings in CI environment
        "--dtype",
        "half",
        "--enable-auto-tool-choice",
        "--structured-outputs-config.backend",
        "xgrammar",
        "--tool-call-parser",
        "hermes",
        "--reasoning-parser",
        "qwen3",
        "--gpu-memory-utilization",
        "0.4"
    ]

    with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:
        yield remote_server


@pytest_asyncio.fixture
async def client(server):
    async with server.get_async_client() as async_client:
        yield async_client


@pytest.mark.asyncio
@pytest.mark.parametrize("model_name", [MODEL_NAME])
@pytest.mark.parametrize("stream", [True, False])
@pytest.mark.parametrize("tool_choice", [
    "auto", "required", {
        "type": "function",
        "function": {
            "name": "get_current_weather"
        }
    }
])
@pytest.mark.parametrize("enable_thinking", [True, False])
async def test_function_tool_use(client: openai.AsyncOpenAI, model_name: str,
                                 stream: bool, tool_choice: Union[str, dict],
                                 enable_thinking: bool):
    if not stream:
        # Non-streaming test
        chat_completion = await client.chat.completions.create(
            messages=messages,
            model=model_name,
            tools=tools,
            tool_choice=tool_choice,
            extra_body={
                "chat_template_kwargs": {
                    "enable_thinking": enable_thinking
                }
            })
        if enable_thinking:
            assert chat_completion.choices[0].message.\
                reasoning_content is not None
            assert chat_completion.choices[0].message.\
                reasoning_content != ""
        assert chat_completion.choices[0].message.tool_calls is not None
        assert len(chat_completion.choices[0].message.tool_calls) > 0
    else:
        # Streaming test
        output_stream = await client.chat.completions.create(
            messages=messages,
            model=model_name,
            tools=tools,
            tool_choice=tool_choice,
            stream=True,
            extra_body={
                "chat_template_kwargs": {
                    "enable_thinking": enable_thinking
                }
            })

        output = []
        async for chunk in output_stream:
            if chunk.choices and chunk.choices[0].delta.tool_calls:
                output.extend(chunk.choices[0].delta.tool_calls)

        assert len(output) > 0


@pytest.fixture(scope="module")
def k2_server():  # noqa: F811
    args = [
        # use half precision for speed and memory savings in CI environment
        "--dtype",
        "half",
        "--enable-auto-tool-choice",
        "--structured-outputs-config.backend",
        "xgrammar",
        "--tool-call-parser",
        "hermes",
        "--reasoning-parser",
        "qwen3",
        "--gpu-memory-utilization",
        "0.4",
    ]
    # hack to test kimi_k2 tool use tool_id format.
    # avoid error in is_deepseek_mla check by setting kv_lora_rank=null
    with RemoteOpenAIServer(MODEL_NAME,
                            args,
                            override_hf_configs={
                                "model_type": 'kimi_k2',
                                'kv_lora_rank': None
                            }) as remote_server:
        yield remote_server


@pytest_asyncio.fixture
async def k2_client(k2_server):
    async with k2_server.get_async_client() as async_client:
        yield async_client


@pytest.mark.asyncio
@pytest.mark.parametrize("model_name", [MODEL_NAME])
@pytest.mark.parametrize("stream", [True, False])
@pytest.mark.parametrize("tool_choice", ["required"])
async def test_tool_id_kimi_k2(k2_client: openai.AsyncOpenAI, model_name: str,
                               stream: bool, tool_choice: str):

    if not stream:
        # Non-streaming test
        chat_completion = await k2_client.chat.completions.create(
            messages=messages,
            model=model_name,
            tools=tools,
            tool_choice=tool_choice)
        assert chat_completion.choices[0].message.tool_calls is not None
        assert len(chat_completion.choices[0].message.tool_calls) > 0
        assert chat_completion.choices[0].message.tool_calls[
            0].id == 'functions.get_current_weather:0'
    else:
        # Streaming test
        output_stream = await k2_client.chat.completions.create(
            messages=messages,
            model=model_name,
            tools=tools,
            tool_choice=tool_choice,
            stream=True)

        output = []
        async for chunk in output_stream:
            if chunk.choices and chunk.choices[0].delta.tool_calls:
                output.extend(chunk.choices[0].delta.tool_calls)
        for o in output:
            assert o.id is None or o.id == 'functions.get_current_weather:0'


@pytest.mark.asyncio
@pytest.mark.parametrize("model_name", [MODEL_NAME])
@pytest.mark.parametrize("arguments", ["{}", ''])
async def test_no_args_tool_call(client: openai.AsyncOpenAI, model_name: str,
                                 arguments: str):
    # Step 1: Define a tool that requires no parameters
    tools = [{
        "type": "function",
        "function": {
            "name": "get_current_time",
            "description":
            "Get the current date and time. No parameters needed.",
            "parameters": {
                "type": "object",
                "properties": {},  # No parameters
                "required": []  # No required fields
            }
        }
    }]
    messages = [{"role": "user", "content": "What time is it now?"}]
    # Step 2: Send user message and let model decide whether to call the tool
    response = await client.chat.completions.create(
        model=model_name,
        messages=messages,
        tools=tools,
        tool_choice="auto"  # Let model choose automatically
    )

    # Step 3: Check if model wants to call a tool
    message = response.choices[0].message
    if message.tool_calls:
        # Get the first tool call
        tool_call = message.tool_calls[0]
        tool_name = tool_call.function.name
        # Step 4: Execute the tool locally (no parameters)
        if tool_name == "get_current_time":
            # Test both empty string and "{}" for no-arg tool calls
            tool_call.function.arguments = arguments
            messages.append(message)
            current_time = datetime.datetime.now()
            result = current_time.isoformat()
            messages.append({
                "role": "tool",
                "tool_call_id": tool_call.id,
                "content": result,
            })
            # Step 5: Send tool result back to model to continue conversation
            final_response = await client.chat.completions.create(
                model=model_name,
                messages=messages,
            )
            # Output final natural language response
            assert final_response.choices[0].message.content is not None

    else:
        # No tool called — just print model's direct reply
        assert message.content is not None