class_docstr: Test utilities used with colormaps.
class_docstr_tok: ["Test","utilities","used","with","colormaps","."]
docstr: Test that being unable to create a colormap raises an error.
code: def test_cmap_no_colormap(self):
      """Test that being unable to create a colormap raises an error."""
      from satpy.enhancements import create_colormap
  
      with pytest.raises(
          ValueError, match="Unknown colormap format: .*"
      ):
          create_colormap({})
  
imports: import contextlib
  import os
  from tempfile import NamedTemporaryFile
  from unittest import mock
  import dask.array
  import numpy
  import pytest
  import xarray
  from satpy.enhancements import create_colormap, on_dask_array, on_separate_bands, using_map_blocks
label_desc: Use image node_id 7 for calling the TestColormapLoading obj's underlying member method code with example usage: obj.test_cmap_no_colormap() without return types