docstr: Test creation of 'reference' ForwardMsgs
docstr_tok: ["Test","creation","of","'reference","'","ForwardMsgs"]
code: def test_reference_msg(self):
      """Test creation of 'reference' ForwardMsgs"""
      msg = create_dataframe_msg([1, 2, 3], 34)
      ref_msg = create_reference_msg(msg)
      self.assertEqual(populate_hash_if_needed(msg), ref_msg.ref_hash)
      self.assertEqual(msg.metadata, ref_msg.metadata)
  
imports: import unittest
  from unittest.mock import MagicMock
  from streamlit import config
  from streamlit.runtime import app_session
  from streamlit.runtime.forward_msg_cache import ForwardMsgCache, create_reference_msg, populate_hash_if_needed
  from streamlit.runtime.stats import CacheStat
  from streamlit.testing.v1.util import patch_config_options
  from tests.streamlit.message_mocks import create_dataframe_msg
label_desc: Use image node_id 3 for calling the ForwardMsgCacheTest obj's underlying member method code with example usage: obj.test_reference_msg() without return types