code: def test_unweighted_graph(self):
      G = nx.Graph()
      G.add_edges_from([(1, 0), (2, 1)])
      H = G.copy()
      nx.set_edge_attributes(H, values=1, name="weight")
      assert nx.johnson(G) == nx.johnson(H)
  
imports: import pytest
  import networkx
  from networkx.utils import pairwise
label_desc: Use image node_id 4 for calling the TestJohnsonAlgorithm obj's underlying member method code with example usage: obj.test_unweighted_graph() without return types