code: def test_io_trans(tmp_path):
      """Test reading and writing of trans files."""
      os.mkdir(tmp_path / "sample")
      pytest.raises(
          RuntimeError, _find_trans, "sample", subjects_dir=tmp_path
      )
      trans0 = read_trans(fname)
      fname1 = tmp_path / "sample" / "test-trans.fif"
      trans0.save(fname1)
      assert fname1 == _find_trans("sample", subjects_dir=tmp_path)
      trans1 = read_trans(fname1)
  
      # check all properties
      assert trans0 == trans1
  
      # check reading non -trans.fif files
      pytest.raises(OSError, read_trans, fname_eve)
  
      # check warning on bad filenames
      fname2 = tmp_path / "trans-test-bad-name.fif"
      with pytest.warns(RuntimeWarning, match="-trans.fif"):
          write_trans(fname2, trans0)
  
imports: import itertools
  import os
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_almost_equal, assert_array_equal, assert_array_less, assert_equal
  import mne
  from mne import read_trans, write_trans
  from mne.datasets import testing
  from mne.fixes import _get_img_fdata
  from mne.io import read_info
  from mne.transforms import _angle_between_quats, _average_quats, _cart_to_sph, _compute_r2, _euler_to_quat, _find_trans, _find_vector_rotation, _fit_matched_points, _get_trans, _MatchedDisplacementFieldInterpolator, _pol_to_cart, _quat_real, _quat_to_affine, _quat_to_euler, _read_fs_xfm, _sph_to_cart, _topo_to_sph, _validate_pipeline, _write_fs_xfm, apply_trans, combine_transforms, get_ras_to_neuromag_trans, invert_transform, quat_to_rot, rot_to_quat, rotation, rotation3d, rotation3d_align_z_axis, rotation_angles, translation
  from mne.transforms import _SphericalSurfaceWarp
label_desc: Use image node_id 3 for calling a global function with example usage: test_io_trans(tmp_path) without return types