[Feature] Function Calling (#2544)

Co-authored-by: Haoyu Wang <120358163+HaoyuWang4188@users.noreply.github.com>

test/srt/test_openai_server.py

@@ -622,6 +622,58 @@ class TestOpenAIServerEBNF(unittest.TestCase):
             text, pattern, f"Text '{text}' not matching the EBNF strict JSON shape"
         )
 
+    def test_function_calling_format(self):
+
+        client = openai.Client(api_key=self.api_key, base_url=self.base_url)
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "add",
+                    "description": "Compute the sum of two numbers",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {
+                            "a": {
+                                "type": "int",
+                                "description": "A number",
+                            },
+                            "b": {
+                                "type": "int",
+                                "description": "A number",
+                            },
+                        },
+                        "required": ["a", "b"],
+                    },
+                },
+            }
+        ]
+
+        messages = [{"role": "user", "content": "Compute (3+5)"}]
+        response = client.chat.completions.create(
+            model=self.model,
+            messages=messages,
+            temperature=0.8,
+            top_p=0.8,
+            stream=False,
+            tools=tools,
+        )
+
+        content = response.choices[0].message.content
+        tool_calls = response.choices[0].message.tool_calls
+
+        assert (
+            content is None
+        ), "When tools provided by the response, content should be None"
+        assert (
+            isinstance(tool_calls, list) and len(tool_calls) > 0
+        ), "Format not matched, tool_calls should be a list"
+
+        function_name = tool_calls[0].function.name
+        assert (
+            function_name == "add"
+        ), "Function name should be add for the above response"
+
 
 if __name__ == "__main__":
     unittest.main()