code: def test_exceptions(self):
      class G:
          format = None
  
      pytest.raises(nx.NetworkXError, nx.to_networkx_graph, G)
  
imports: import pytest
  import networkx
  from networkx.generators.classic import barbell_graph, cycle_graph, path_graph
  from networkx.utils import graphs_equal
label_desc: Use image node_id 2 for calling the TestConvertScipy obj's underlying member method code with example usage: obj.test_exceptions() without return types