code: def test_color_str():
      clr = colors.Color("k")
      assert (0.0, 0.0, 0.0) == clr
      clr = colors.Color("black")
      assert (0.0, 0.0, 0.0) == clr
      clr = colors.Color("white")
      assert (1.0, 1.0, 1.0) == clr
      with pytest.raises(ValueError):
          colors.Color("not a color")
  
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 11 for calling a global function with example usage: test_color_str() without return types