code: def test_null_graph(self):
      g = Graph()
      fig = go.Figure()
      plot(g, target=fig)
      return fig
  
imports: import unittest
  from igraph import Graph, plot, VertexClustering
label_desc: Use image node_id 8 for calling the GraphTestRunner obj's underlying member method code with example usage: obj.test_null_graph() and returns: fig