code: def test_adjacency_field_empty_field_works(self):
      field = AdjacencyField([(0, 1)], self.text)
      empty_field = field.empty_field()
      assert empty_field.indices == []
  
file_path: allennlp/tests/data/fields/adjacency_field_test.py
imports: import pytest
  import numpy
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data.fields import AdjacencyField, TextField
  from allennlp.data.token_indexers import SingleIdTokenIndexer
  from allennlp.data import Vocabulary, Token
label_desc: Use image node_id 6 for calling the TestAdjacencyField obj's underlying member method code with example usage: obj.test_adjacency_field_empty_field_works() without return types