code: def test_nonexistent_nodes(self):
      G = nx.complete_graph(5)
      pytest.raises(nx.NetworkXError, nx.common_neighbors, G, 5, 4)
      pytest.raises(nx.NetworkXError, nx.common_neighbors, G, 4, 5)
      pytest.raises(nx.NetworkXError, nx.common_neighbors, G, 5, 6)
  
imports: import random
  import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 6 for calling the TestCommonNeighbors obj's underlying member method code with example usage: obj.test_nonexistent_nodes() without return types