[gpt-oss] tool parser supports for /chat/completions [1/n] (#22386)

Signed-off-by: Aaron Pham <contact@aarnphm.xyz>
Co-authored-by: Simon Mo <simon.mo@hey.com>

tests/entrypoints/openai/test_serving_chat.py

@@ -1,13 +1,16 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
+from __future__ import annotations
+
 import asyncio
 from contextlib import suppress
 from dataclasses import dataclass, field
-from typing import Any, Optional
+from typing import TYPE_CHECKING, Any, Optional
 from unittest.mock import MagicMock
 
 import pytest
+import pytest_asyncio
 
 from vllm.config import MultiModalConfig
 from vllm.engine.multiprocessing.client import MQLLMEngineClient
@@ -17,6 +20,164 @@ from vllm.entrypoints.openai.serving_models import (BaseModelPath,
                                                     OpenAIServingModels)
 from vllm.transformers_utils.tokenizer import get_tokenizer
 
+from ...utils import RemoteOpenAIServer
+
+if TYPE_CHECKING:
+    from openai import OpenAI
+
+GPT_OSS_MODEL_NAME = "openai/gpt-oss-20b"
+
+
+@pytest.fixture(scope="module")
+def monkeypatch_module():
+    from _pytest.monkeypatch import MonkeyPatch
+    mpatch = MonkeyPatch()
+    yield mpatch
+    mpatch.undo()
+
+
+@pytest.fixture(scope="module")
+def gptoss_server(monkeypatch_module: pytest.MonkeyPatch):
+    with monkeypatch_module.context() as m:
+        m.setenv("VLLM_ATTENTION_BACKEND", "TRITON_ATTN_VLLM_V1")
+        args = [
+            "--enforce-eager",
+            "--max-model-len",
+            "8192",
+            "--tool-call-parser",
+            "openai",
+            "--reasoning-parser",
+            "openai_gptoss",
+            "--enable-auto-tool-choice",
+        ]
+        with RemoteOpenAIServer(GPT_OSS_MODEL_NAME, args) as remote_server:
+            yield remote_server
+
+
+@pytest_asyncio.fixture
+async def gptoss_client(gptoss_server):
+    async with gptoss_server.get_async_client() as async_client:
+        yield async_client
+
+
+@pytest.mark.asyncio
+async def test_gpt_oss_chat_tool_call_streaming(gptoss_client: OpenAI):
+    tools = [{
+        "type": "function",
+        "function": {
+            "name": "get_current_weather",
+            "description": "Get the current weather in a given location",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "city": {
+                        "type": "string"
+                    },
+                    "state": {
+                        "type": "string"
+                    },
+                    "unit": {
+                        "type": "string",
+                        "enum": ["celsius", "fahrenheit"],
+                    },
+                },
+                "required": ["city", "state", "unit"],
+            },
+        },
+    }]
+
+    messages = [
+        {
+            "role": "user",
+            "content": "What is the weather in Dallas, TX?"
+        },
+    ]
+
+    stream = await gptoss_client.chat.completions.create(
+        model=GPT_OSS_MODEL_NAME, messages=messages, tools=tools, stream=True)
+
+    name = None
+    args_buf = ""
+    async for chunk in stream:
+        delta = chunk.choices[0].delta
+        if delta.tool_calls:
+            tc = delta.tool_calls[0]
+            if tc.function and tc.function.name:
+                name = tc.function.name
+            if tc.function and tc.function.arguments:
+                args_buf += tc.function.arguments
+
+    assert name is not None
+    assert len(args_buf) > 0
+
+
+@pytest.mark.asyncio
+async def test_gpt_oss_multi_turn_chat(gptoss_client: OpenAI):
+    tools = [{
+        "type": "function",
+        "function": {
+            "name": "get_current_weather",
+            "description": "Get the current weather in a given location",
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "city": {
+                        "type": "string"
+                    },
+                    "state": {
+                        "type": "string"
+                    },
+                    "unit": {
+                        "type": "string",
+                        "enum": ["celsius", "fahrenheit"],
+                    },
+                },
+                "required": ["city", "state", "unit"],
+            },
+        },
+    }]
+
+    messages = [
+        {
+            "role": "system",
+            "content": "you are a helpful assistant"
+        },
+        {
+            "role": "user",
+            "content": "What is the weather in Dallas, TX?"
+        },
+    ]
+
+    first = await gptoss_client.chat.completions.create(
+        model=GPT_OSS_MODEL_NAME,
+        messages=messages,
+        tools=tools,
+        temperature=0.0,
+    )
+    first_msg = first.choices[0].message
+    assert first_msg.tool_calls is not None and len(first_msg.tool_calls) > 0
+    tc = first_msg.tool_calls[0]
+    assert tc.function is not None and tc.function.name == "get_current_weather"
+    args1 = tc.function.arguments
+    assert args1 is not None and len(args1) > 0
+
+    messages.append({"role": "assistant", "content": args1})
+    messages.append({
+        "role": "user",
+        "content": "Now convert to celsius and return JSON only"
+    })
+
+    second = await gptoss_client.chat.completions.create(
+        model=GPT_OSS_MODEL_NAME,
+        messages=messages,
+        tools=tools,
+        temperature=0.0,
+    )
+    second_msg = second.choices[0].message
+    assert (second_msg.content is not None and len(second_msg.content) > 0) or \
+        (second_msg.tool_calls is not None and len(second_msg.tool_calls) > 0)  # noqa: E501
+
+
 MODEL_NAME = "openai-community/gpt2"
 CHAT_TEMPLATE = "Dummy chat template for testing {}"
 BASE_MODEL_PATHS = [BaseModelPath(name=MODEL_NAME, model_path=MODEL_NAME)]