code: def setup_class(cls):
      # a tree
      G = nx.Graph()
      nx.add_path(G, [0, 1, 2, 3, 4, 5, 6])
      nx.add_path(G, [2, 7, 8, 9, 10])
      cls.G = G
      # a disconnected graph
      D = nx.Graph()
      D.add_edges_from([(0, 1), (2, 3)])
      nx.add_path(D, [2, 7, 8, 9, 10])
      cls.D = D
  
imports: from functools import partial
  import pytest
  import networkx
label_desc: Use image node_id 1 for calling the TestBreadthLimitedSearch obj's underlying member method code with example usage: obj.setup_class(cls) without return types