class_docstr: Test DataVisualizer base class
class_docstr_tok: ["Test","DataVisualizer","base","class"]
docstr: Assert get_colors requires an fitted visualizer
code: def test_get_colors_not_fitted(self):
      """
      Assert get_colors requires an fitted visualizer
      """
      oz = DataVisualizer()
      with pytest.raises(NotFitted, match="cannot determine colors"):
          oz.get_colors(["a", "b", "c"])
  
imports: import pytest
  import numpy
  import numpy.testing
  from tests.fixtures import Dataset
  from yellowbrick.base import Visualizer
  from yellowbrick.features.base import *
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.datasets import make_classification, make_regression
  from unittest.mock import Mock
label_desc: Use image node_id 12 for calling the TestDataVisualizer obj's underlying member method code with example usage: obj.test_get_colors_not_fitted() without return types