code: def test_mapper_no_bond():
      """
      Test 'C' in _MapperDMPNN (no bond present)
      """
      mapper = _MapperDMPNN(graphs[0])
      assert (mapper.bond_to_ini_atom == np.empty(0)).all()
      assert (mapper.atom_to_incoming_bonds == np.asarray([[-1]])).all()
      assert (mapper.mapping == np.asarray([[-1]])).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 2 for calling a global function with example usage: test_mapper_no_bond() without return types