code: def test_should_not_raise_warning_if_backend_is_not_changed(*_):
      # The backend values returned by matplotlib.get_backend are identical.
      # Warning should not be raised.
      with warnings.catch_warnings():
          warnings.simplefilter("error")
          _set_mpl_backend()
  
file_path: nilearn/nilearn/plotting/tests/test_matplotlib_backend.py
imports: from unittest.mock import patch
  import warnings
  import pytest
  from nilearn.plotting import _set_mpl_backend
label_desc: Use image node_id 2 for calling a global function with example usage: test_should_not_raise_warning_if_backend_is_not_changed() without return types