[Frontend] Added support for HermesToolParser for models without special tokens (#16890)

Signed-off-by: minpeter <kali2005611@gmail.com>

tests/entrypoints/openai/tool_parsers/test_hermes_tool_parser.py

@@ -0,0 +1,127 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import json
+
+import pytest
+
+from ....utils import RemoteOpenAIServer
+
+MODEL_NAME = "meta-llama/Llama-3.2-1B-Instruct"
+LORA_MODEL = "minpeter/LoRA-Llama-3.2-1B-tool-vllm-ci"
+
+SERVER_ARGS = [
+    "--enforce-eager",
+    "--enable-auto-tool-choice",
+    "--tool-call-parser",
+    "hermes",
+    "--enable-lora",
+    "--lora-modules",
+    f"{LORA_MODEL}={LORA_MODEL}",
+]
+
+TOOLS = [{
+    "type": "function",
+    "function": {
+        "name": "get_current_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {
+            "type": "object",
+            "properties": {
+                "location": {
+                    "type": "string",
+                    "description":
+                    "The city and state, e.g. San Francisco, CA",
+                },
+                "unit": {
+                    "type": "string",
+                    "enum": ["celsius", "fahrenheit"]
+                },
+            },
+            "required": ["location"],
+        },
+    },
+}]
+
+MESSAGES = [{"role": "user", "content": "What's the weather like in Boston?"}]
+
+
+@pytest.mark.asyncio
+async def test_non_streaming_tool_call():
+    """Test tool call in non-streaming mode."""
+    with RemoteOpenAIServer(MODEL_NAME, SERVER_ARGS) as server:
+        client = server.get_async_client()
+
+        response = await client.chat.completions.create(
+            model=LORA_MODEL,
+            messages=MESSAGES,
+            tools=TOOLS,
+            tool_choice="auto",
+            temperature=0.0,
+        )
+
+        assert response.choices
+        choice = response.choices[0]
+        message = choice.message
+
+        assert choice.finish_reason == "tool_calls"
+        assert message.tool_calls is not None
+
+        tool_call = message.tool_calls[0]
+        assert tool_call.type == "function"
+        assert tool_call.function.name == "get_current_weather"
+
+        arguments = json.loads(tool_call.function.arguments)
+        assert "location" in arguments
+        assert "Boston" in arguments["location"]
+        print("\n[Non-Streaming Test Passed]")
+        print(f"Tool Call: {tool_call.function.name}")
+        print(f"Arguments: {arguments}")
+
+
+@pytest.mark.asyncio
+async def test_streaming_tool_call():
+    """Test tool call in streaming mode."""
+    with RemoteOpenAIServer(MODEL_NAME, SERVER_ARGS) as server:
+        client = server.get_async_client()
+
+        stream = await client.chat.completions.create(
+            model=LORA_MODEL,
+            messages=MESSAGES,
+            tools=TOOLS,
+            tool_choice="auto",
+            temperature=0.0,
+            stream=True,
+        )
+
+        tool_call_chunks = {}
+        async for chunk in stream:
+            if not chunk.choices:
+                continue
+
+            delta = chunk.choices[0].delta
+            if not delta or not delta.tool_calls:
+                continue
+
+            for tool_chunk in delta.tool_calls:
+                index = tool_chunk.index
+                if index not in tool_call_chunks:
+                    tool_call_chunks[index] = {"name": "", "arguments": ""}
+
+                if tool_chunk.function.name:
+                    tool_call_chunks[index]["name"] += tool_chunk.function.name
+                if tool_chunk.function.arguments:
+                    tool_call_chunks[index][
+                        "arguments"] += tool_chunk.function.arguments
+
+        assert len(tool_call_chunks) == 1
+        reconstructed_tool_call = tool_call_chunks[0]
+
+        assert reconstructed_tool_call["name"] == "get_current_weather"
+
+        arguments = json.loads(reconstructed_tool_call["arguments"])
+        assert "location" in arguments
+        assert "Boston" in arguments["location"]
+        print("\n[Streaming Test Passed]")
+        print(f"Reconstructed Tool Call: {reconstructed_tool_call['name']}")
+        print(f"Reconstructed Arguments: {arguments}")