code: def test_null_raise(self):
      with pytest.raises(nx.NetworkXError):
          nx.to_scipy_sparse_array(nx.Graph())
  
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 14 for calling the TestConvertScipy obj's underlying member method code with example usage: obj.test_null_raise() without return types