class_docstr: Unit tests for the :func:`~networkx.node_boundary` function.
class_docstr_tok: ["Unit","tests","for","the",":","func",":","`","~networkx.node_boundary","`","function","."]
docstr: Tests the node boundary of a directed graph.
docstr_tok: ["Tests","the","node","boundary","of","a","directed","graph","."]
code: def test_directed(self):
      """Tests the node boundary of a directed graph."""
      G = nx.DiGraph([(0, 1), (1, 2), (2, 3), (3, 4), (4, 0)])
      S = {0, 1}
      boundary = nx.node_boundary(G, S)
      expected = {2}
      assert boundary == expected
  
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 5 for calling the TestNodeBoundary obj's underlying member method code with example usage: obj.test_directed() without return types