docstr: Enqueue a single ForwardMsg.
docstr_tok: ["Enqueue","a","single","ForwardMsg","."]
code: def test_simple_enqueue(self):
      """Enqueue a single ForwardMsg."""
      rq = ForwardMsgQueue()
      self.assertTrue(rq.is_empty())
  
      rq.enqueue(NEW_SESSION_MSG)
  
      self.assertFalse(rq.is_empty())
      queue = rq.flush()
      self.assertTrue(rq.is_empty())
      self.assertEqual(1, len(queue))
      self.assertTrue(queue[0].new_session.config.allow_run_on_save)
  
file_path: streamlit/lib/tests/streamlit/runtime/forward_msg_queue_test.py
imports: import copy
  import unittest
  from typing import Tuple
  from parameterized import parameterized
  from streamlit.cursor import make_delta_path
  from streamlit.elements import arrow
  from streamlit.proto.ForwardMsg_pb2 import ForwardMsg
  from streamlit.proto.RootContainer_pb2 import RootContainer
  from streamlit.runtime.forward_msg_queue import ForwardMsgQueue
label_desc: Use image node_id 1 for calling the ForwardMsgQueueTest obj's underlying member method code with example usage: obj.test_simple_enqueue() without return types