code: def test_atom_features_none():
      """
      Test for atom_features() with 'None' input for Atom value
      """
      f_atom = atom_features(None)
      req_f = list(np.zeros((133,), dtype=int))
      assert len(f_atom) == len(req_f)
      assert f_atom == req_f
  
file_path: deepchem/deepchem/feat/tests/test_atom_feature_generator_dmpnn.py
imports: from deepchem.feat.molecule_featurizers.dmpnn_featurizer import get_atomic_num_one_hot, get_atom_chiral_tag_one_hot, get_atom_mass, atom_features, GraphConvConstants
  from rdkit import Chem
  import pytest
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: test_atom_features_none() without return types