code: def test_execute_function():
      from autogen.agentchat import UserProxyAgent
  
      # 1. test calling a simple function
      def add_num(num_to_be_added):
          given_num = 10
          return num_to_be_added + given_num
  
      user = UserProxyAgent(
          name="test", function_map={"add_num": add_num}
      )
  
      # correct execution
      correct_args = {
          "name": "add_num",
          "arguments": '{ "num_to_be_added": 5 }',
      }
      assert (
          user.execute_function(func_call=correct_args)[1]["content"]
          == "15"
      )
  
      # function name called is wrong or doesn't exist
      wrong_func_name = {
          "name": "subtract_num",
          "arguments": '{ "num_to_be_added": 5 }',
      }
      assert (
          "Error: Function"
          in user.execute_function(func_call=wrong_func_name)[1][
              "content"
          ]
      )
  
      # arguments passed is not in correct json format
      wrong_json_format = {
          "name": "add_num",
          "arguments": '{ "num_to_be_added": 5, given_num: 10 }',
      }  # should be "given_num" with quotes
      assert (
          "You argument should follow json format."
          in user.execute_function(func_call=wrong_json_format)[1][
              "content"
          ]
      )
  
      # function execution error with wrong arguments passed
      wrong_args = {
          "name": "add_num",
          "arguments": '{ "num_to_be_added": 5, "given_num": 10 }',
      }
      assert (
          "Error: "
          in user.execute_function(func_call=wrong_args)[1]["content"]
      )
  
      # 2. test calling a class method
      class AddNum:
          def __init__(self, given_num):
              self.given_num = given_num
  
          def add(self, num_to_be_added):
              self.given_num = num_to_be_added + self.given_num
              return self.given_num
  
      user = UserProxyAgent(
          name="test",
          function_map={"add_num": AddNum(given_num=10).add},
      )
      func_call = {
          "name": "add_num",
          "arguments": '{ "num_to_be_added": 5 }',
      }
      assert (
          user.execute_function(func_call=func_call)[1]["content"]
          == "15"
      )
      assert (
          user.execute_function(func_call=func_call)[1]["content"]
          == "20"
      )
  
      # 3. test calling a function with no arguments
      def get_number():
          return 42
  
      user = UserProxyAgent(
          "user", function_map={"get_number": get_number}
      )
      func_call = {"name": "get_number", "arguments": "{}"}
      assert user.execute_function(func_call)[1]["content"] == "42"
  
file_path: autogen/test/agentchat/test_function_call.py
imports: import pytest
  import asyncio
  import json
  import autogen
  from autogen.math_utils import eval_math_responses
  from test_assistant_agent import KEY_LOC, OAI_CONFIG_LIST
  import sys
  import os
  from conftest import skip_openai
label_desc: Use image node_id 3 for calling a global function with example usage: test_execute_function() and returns: unknown, int, self