class_docstr: Test the core functionality of the VQE module
class_docstr_tok: ["Test","the","core","functionality","of","the","VQE","module"]
docstr: Tests that the cost function raises an exception if the ansatz is not valid
docstr_tok: ["Tests","that","the","cost","function","raises","an","exception","if","the","ansatz","is","not","valid"]
code: def test_cost_invalid_ansatz(self, ansatz, mock_device):
      """Tests that the cost function raises an exception if the ansatz is not valid"""
      hamiltonian = qml.Hamiltonian((1.0,), [qml.PauliZ(0)])
      with pytest.raises(ValueError, match="not a callable function."):
          catch_warn_ExpvalCost(4, hamiltonian, mock_device())
  
imports: import copy
  import numpy
  import pytest
  import pennylane
  from pennylane import numpy
label_desc: Use image node_id 3 for calling the TestVQE obj's underlying member method code with example usage: obj.test_cost_invalid_ansatz(ansatz, mock_device) without return types