code: def test_non_edges(self):
      # All possible edges exist
      graph = nx.complete_graph(5)
      nedges = list(nx.non_edges(graph))
      assert len(nedges) == 0
  
      graph = nx.path_graph(4)
      expected = [(0, 2), (0, 3), (1, 3)]
      nedges = list(nx.non_edges(graph))
      for u, v in expected:
          assert (u, v) in nedges or (v, u) in nedges
  
      graph = nx.star_graph(4)
      expected = [(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]
      nedges = list(nx.non_edges(graph))
      for u, v in expected:
          assert (u, v) in nedges or (v, u) in nedges
  
      # Directed graphs
      graph = nx.DiGraph()
      graph.add_edges_from([(0, 2), (2, 0), (2, 1)])
      expected = [(0, 1), (1, 0), (1, 2)]
      nedges = list(nx.non_edges(graph))
      for e in expected:
          assert e in nedges
  
imports: import random
  import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 24 for calling the TestFunction obj's underlying member method code with example usage: obj.test_non_edges() without return types