code: def test_graphs(self):
      validate_path(self.XG, "s", "v", 9, nx.johnson(self.XG)["s"]["v"])
      validate_path(
          self.MXG, "s", "v", 9, nx.johnson(self.MXG)["s"]["v"]
      )
      validate_path(self.XG2, 1, 3, 4, nx.johnson(self.XG2)[1][3])
      validate_path(self.XG3, 0, 3, 15, nx.johnson(self.XG3)[0][3])
      validate_path(self.XG4, 0, 2, 4, nx.johnson(self.XG4)[0][2])
      validate_path(self.MXG4, 0, 2, 4, nx.johnson(self.MXG4)[0][2])
  
imports: import pytest
  import networkx
  from networkx.utils import pairwise
label_desc: Use image node_id 6 for calling the TestJohnsonAlgorithm obj's underlying member method code with example usage: obj.test_graphs() without return types