code: def test_cube_axes_actor():
      pl = pv.Plotter()
      actor = pv.CubeAxesActor(
          pl.camera,
          x_label_format=None,
          y_label_format=None,
          z_label_format=None,
      )
      assert isinstance(actor.camera, pv.Camera)
  
      # ensure label format is set to default
      assert actor.x_label_format == "%.1f"
      assert actor.y_label_format == "%.1f"
      assert actor.z_label_format == "%.1f"
  
file_path: pyvista/tests/plotting/test_cube_axes_actor.py
imports: import numpy
  import pytest
  import pyvista
label_desc: Use image node_id 3 for calling a global function with example usage: test_cube_axes_actor() without return types