code: def test_mapper_ring():
      """
      Test 'C1=CC=CC=C1' in _MapperDMPNN (benezene ring)
      """
      mapper = _MapperDMPNN(graphs[3])
      assert (
          mapper.bond_to_ini_atom
          == np.asarray([0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 0])
      ).all()
      assert (
          mapper.atom_to_incoming_bonds
          == benezene_atom_to_incoming_bonds
      ).all()
      assert (mapper.mapping == benezene_mapping).all()
  
file_path: deepchem/deepchem/models/tests/test_mapper_dmpnn.py
imports: from deepchem.feat import DMPNNFeaturizer
  import numpy
  import pytest
label_desc: Use image node_id 5 for calling a global function with example usage: test_mapper_ring() without return types