text: import unittest
  
  import numpy as np
  
  from autosklearn.pipeline.components.feature_preprocessing.densifier import Densifier
  from autosklearn.pipeline.util import _test_preprocessing, PreprocessingTestCase
  
  
  class DensifierComponentTest(PreprocessingTestCase):
      def test_default_configuration(self):
          transformation, original = _test_preprocessing(Densifier, make_sparse=True)
          self.assertIsInstance(transformation, np.ndarray)
          self.assertEqual(transformation.shape, original.shape)
          self.assertIsInstance(transformation, np.ndarray)
  
      def test_preprocessing_dtype(self):
          super(DensifierComponentTest, self)._test_preprocessing_dtype(Densifier)
  
  