code: def test_undirected_not_connected(self):
      g = nx.Graph()
      g.add_nodes_from(range(3))
      g.add_edge(0, 1)
      pytest.raises(
          nx.NetworkXError, nx.average_shortest_path_length, g
      )
  
imports: import pytest
  import networkx
label_desc: Use image node_id 6 for calling the TestAverageShortestPathLength obj's underlying member method code with example usage: obj.test_undirected_not_connected() without return types