code: def test_plugin_manager() -> None:
      manager = plugin_manager()
      assert isinstance(manager, PluginManager)
  
      manager_2 = plugin_manager()
      assert manager_2 == manager
  
file_path: rasa/tests/test_plugin.py
imports: import warnings
  from typing import Optional, Text
  from unittest.mock import MagicMock
  import pytest
  from pluggy import PluginManager
  from pytest import MonkeyPatch
  from rasa.core.brokers.broker import EventBroker
  from rasa.core.tracker_store import TrackerStore
  from rasa.plugin import plugin_manager
  from rasa.shared.core.domain import Domain
  from rasa.utils.endpoints import EndpointConfig
label_desc: Use image node_id 1 for calling a global function with example usage: test_plugin_manager() without return types