code: def test_does_nothing_if_NoOpPathWatcher(self):
      lsw = local_sources_watcher.LocalSourcesWatcher(SCRIPT_PATH)
      lsw.register_file_change_callback(NOOP_CALLBACK)
      lsw.update_watched_modules()
      self.assertEqual(len(lsw._watched_modules), 0)
  
imports: import os
  import sys
  import unittest
  from unittest.mock import MagicMock, patch
  import tests.streamlit.watcher.test_data.dummy_module1
  import tests.streamlit.watcher.test_data.dummy_module2
  import tests.streamlit.watcher.test_data.misbehaved_module
  import tests.streamlit.watcher.test_data.nested_module_child
  import tests.streamlit.watcher.test_data.nested_module_parent
  from streamlit import config
  from streamlit.watcher import local_sources_watcher
  from streamlit.watcher.path_watcher import NoOpPathWatcher, watchdog_available
label_desc: Use image node_id 10 for calling the LocalSourcesWatcherTest obj's underlying member method code with example usage: obj.test_does_nothing_if_NoOpPathWatcher() without return types