class_docstr: A unittest class for testing the KnockoffNets attack.
code: def test_1_classifier_type_check_fail(self):
      backend_test_classifier_type_check_fail(
          KnockoffNets, [BaseEstimator, ClassifierMixin]
      )
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import logging
  import unittest
  import numpy
  import keras.backend
  from art.attacks.extraction.knockoff_nets import KnockoffNets
  from art.estimators.estimator import BaseEstimator
  from art.estimators.classification.classifier import ClassifierMixin
  from tests.utils import TestBase, master_seed
  from tests.utils import get_image_classifier_tf, get_image_classifier_kr, get_image_classifier_pt
  from tests.utils import get_tabular_classifier_tf, get_tabular_classifier_kr, get_tabular_classifier_pt
  from tests.attacks.utils import backend_test_classifier_type_check_fail
label_desc: Use image node_id 6 for calling the TestKnockoffNets obj's underlying member method code with example usage: obj.test_1_classifier_type_check_fail() without return types