code: def testClusteringOfNullGraph(self):
      null_graph = Graph()
      cl = VertexClustering(null_graph, [])
      self.assertTrue(cl.sizes() == [])
      self.assertTrue(cl.giant().vcount() == 0)
      self.assertTrue(cl.giant().ecount() == 0)
  
imports: import math
  import random
  import unittest
  from igraph import Clustering, CohesiveBlocks, Cover, Graph, Histogram, InternalError, UniqueIdGenerator, VertexClustering, compare_communities, split_join_distance, set_random_number_generator
label_desc: Use image node_id 6 for calling the VertexClusteringTests obj's underlying member method code with example usage: obj.testClusteringOfNullGraph() without return types