code: def test_on_missing():
      """Test _on_missing."""
      msg = "test"
      with pytest.raises(ValueError, match=msg):
          _on_missing("raise", msg)
      with pytest.warns(RuntimeWarning, match=msg):
          _on_missing("warn", msg)
      _on_missing("ignore", msg)
  
      with pytest.raises(
          ValueError,
          match="Invalid value for the 'on_missing' parameter",
      ):
          _on_missing("foo", msg)
  
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 10 for calling a global function with example usage: test_on_missing() without return types