code: def test_disconnected(self, method):
      G = nx.Graph()
      G.add_nodes_from(range(2))
      assert nx.algebraic_connectivity(G) == 0
      pytest.raises(
          nx.NetworkXError, nx.fiedler_vector, G, method=method
      )
      G.add_edge(0, 1, weight=0)
      assert nx.algebraic_connectivity(G) == 0
      pytest.raises(
          nx.NetworkXError, nx.fiedler_vector, G, method=method
      )
  
imports: from math import sqrt
  import pytest
  import networkx
label_desc: Use image node_id 3 for calling the TestAlgebraicConnectivity obj's underlying member method code with example usage: obj.test_disconnected(method) without return types