code: def test_check_ch_locs():
      """Test _check_ch_locs behavior."""
      info = mne.io.read_info(fname_raw)
      assert _check_ch_locs(info=info)
  
      for picks in ([0], [0, 1], None):
          assert _check_ch_locs(info=info, picks=picks)
  
      for ch_type in ("meg", "mag", "grad", "eeg"):
          assert _check_ch_locs(info=info, ch_type=ch_type)
  
      # drop locations for EEG
      picks_eeg = _picks_to_idx(info=info, picks="eeg")
      for idx in picks_eeg:
          info["chs"][idx]["loc"][:3] = np.nan
  
      # EEG tests should fail now
      assert _check_ch_locs(info=info, picks=picks_eeg) is False
      assert _check_ch_locs(info=info, ch_type="eeg") is False
  
      # tests for other (and "all") channels should still pass
      assert _check_ch_locs(info=info)
      assert _check_ch_locs(info=info, ch_type="mag")
  
imports: import os
  import sys
  from pathlib import Path
  import numpy
  import pytest
  import mne
  from mne import pick_channels_cov, read_vectorview_selection
  from mne._fiff.pick import _picks_to_idx
  from mne.datasets import testing
  from mne.utils import Bunch, _check_ch_locs, _check_fname, _check_info_inv, _check_option, _check_range, _check_sphere, _check_subject, _on_missing, _path_like, _safe_input, _suggest, _validate_type, catch_logging, check_fname, check_random_state, check_version
label_desc: Use image node_id 13 for calling a global function with example usage: test_check_ch_locs() without return types