class_docstr: Test DataVisualizer base class
class_docstr_tok: ["Test","DataVisualizer","base","class"]
docstr: Even if a user supplies a target type it should be overriden by y=None
code: def test_none_overrides_user_specified_target(self, target_type):
      """
      Even if a user supplies a target type it should be overriden by y=None
      """
      X, _ = getattr(self, target_type)
      oz = DataVisualizer(target_type=target_type).fit(X, y=None)
  
      assert oz._colors == "C0"
      assert oz._target_color_type == TargetType.SINGLE
  
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 4 for calling the TestDataVisualizer obj's underlying member method code with example usage: obj.test_none_overrides_user_specified_target(target_type) without return types