code: def test_vertical_cs(axis, direction, unit_name):
      vcs = VerticalCS(axis=axis)
      assert len(vcs.axis_list) == 1
      assert vcs.axis_list[0].direction == direction
      assert vcs.axis_list[0].unit_name == unit_name
  
file_path: pyproj/test/crs/test_crs_coordinate_system.py
imports: import pytest
  from pyproj.crs.coordinate_system import Cartesian2DCS, Ellipsoidal2DCS, Ellipsoidal3DCS, VerticalCS
  from pyproj.crs.enums import Cartesian2DCSAxis, Ellipsoidal2DCSAxis, Ellipsoidal3DCSAxis, VerticalCSAxis
label_desc: Use image node_id 1 for calling a global function with example usage: test_vertical_cs(axis, direction, unit_name) without return types