code: def test_empty_graph(self):
      G = nx.empty_graph()
      vpos = nx.random_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.circular_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.planar_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.bipartite_layout(G, G)
      assert vpos == {}
      vpos = nx.spring_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.fruchterman_reingold_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.spectral_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.shell_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.spiral_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.multipartite_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.kamada_kawai_layout(G, center=(1, 1))
      assert vpos == {}
      vpos = nx.arf_layout(G)
      assert vpos == {}
  
imports: import pytest
  import networkx
label_desc: Use image node_id 21 for calling the TestLayout obj's underlying member method code with example usage: obj.test_empty_graph() without return types