class_docstr: Unit tests for the :func:`~networkx.edge_boundary` function.
class_docstr_tok: ["Unit","tests","for","the",":","func",":","`","~networkx.edge_boundary","`","function","."]
code: def test_null_graph(self):
      null = nx.null_graph()
      assert list(nx.edge_boundary(null, [])) == []
      assert list(nx.edge_boundary(null, [], [])) == []
      assert list(nx.edge_boundary(null, [1, 2, 3])) == []
      assert list(nx.edge_boundary(null, [1, 2, 3], [4, 5, 6])) == []
      assert list(nx.edge_boundary(null, [1, 2, 3], [3, 4, 5])) == []
  
imports: from itertools import combinations
  import pytest
  import networkx
  from networkx import convert_node_labels_to_integers
  from networkx.utils import edges_equal
label_desc: Use image node_id 1 for calling the TestEdgeBoundary obj's underlying member method code with example usage: obj.test_null_graph() without return types