class_docstr: Test class for preprocessing tests.
docstr: Clean up after tests.
docstr_tok: ["Clean","up","after","tests","."]
code: def tearDownClass(cls):
      """Clean up after tests."""
      for output_file in output_dir.glob("test_class_map*"):
          os.unlink(output_file)
  
      for dir_path in [train_dir, test_dir]:
          unlink(dir_path / "test_class_map.jsonlines")
  
      config_files = [
          "test_class_map.cfg",
          "test_class_map_feature_hasher.cfg",
      ]
      for cf in config_files:
          unlink(config_dir / cf)
  
imports: import json
  import os
  import re
  import unittest
  import numpy
  import scipy.sparse
  from numpy.testing import assert_almost_equal, assert_array_equal
  from sklearn.datasets import make_classification
  from sklearn.feature_extraction import FeatureHasher
  from skll.data import FeatureSet, NDJWriter
  from skll.experiments import run_configuration
  from skll.learner import Learner
  from skll.learner.utils import SelectByMinCount
  from skll.utils.testing import config_dir, fill_in_config_paths, output_dir, test_dir, train_dir, unlink
label_desc: Use image node_id 2 for calling the TestPreprocessing obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types