code: def test_cmap(default_theme):
      cmap = "jet"
      default_theme.cmap = cmap
      assert default_theme.cmap == cmap
  
      with pytest.raises(ValueError, match="not a color map"):
          default_theme.cmap = "not a color map"
  
      with pytest.raises(ValueError, match="Invalid color map"):
          default_theme.cmap = None
  
imports: import os
  import pytest
  import vtk
  import pyvista
  from pyvista import colors
  from pyvista.examples.downloads import download_file
  from pyvista.plotting.themes import DarkTheme, Theme, _set_plot_theme_from_env
  from pyvista.plotting.utilities.gl_checks import uses_egl
label_desc: Use image node_id 34 for calling a global function with example usage: test_cmap(default_theme) without return types