class_docstr: The MockVisualizer implements the ProjectionVisualizer interface using
  PCA as an internal transformer. This visualizer is used to directly test
  how subclasses interact with the ProjectionVisualizer base class.
class_docstr_tok: ["The","MockVisualizer","implements","the","ProjectionVisualizer","interface","using","PCA","as","an","internal","transformer",".","This","visualizer","is","used","to","directly","test","how","subclasses","interact","with","the","ProjectionVisualizer","base","class","."]
code: def fit(self, X, y=None):
      super(MockVisualizer, self).fit(X, y)
      self.pca_transformer.fit(X)
      return self
  
imports: import pytest
  import numpy.testing
  import matplotlib.pyplot
  from yellowbrick.features.projection import *
  from yellowbrick.exceptions import YellowbrickValueError
  from tests.base import VisualTestCase
  from unittest import mock
  from sklearn.decomposition import PCA
  from sklearn.pipeline import Pipeline
  from sklearn.preprocessing import StandardScaler
label_desc: Use image node_id 2 for calling the MockVisualizer obj's underlying member method code with example usage: obj.fit(X, y) and returns: self