class_docstr: Test the core functionality of the VQE module
class_docstr_tok: ["Test","the","core","functionality","of","the","VQE","module"]
docstr: Test that an ExpvalCost with observable optimization gives the same result as another
  ExpvalCost without observable optimization.
docstr_tok: ["Test","that","an","ExpvalCost","with","observable","optimization","gives","the","same","result","as","another","ExpvalCost","without","observable","optimization","."]
code: def test_optimize_tf(self, shots):
      """Test that an ExpvalCost with observable optimization gives the same result as another
      ExpvalCost without observable optimization."""
  
      dev = qml.device("default.qubit", wires=4, shots=shots)
  
      hamiltonian1 = copy.copy(big_hamiltonian)
      hamiltonian2 = copy.copy(big_hamiltonian)
  
      cost = catch_warn_ExpvalCost(
          qml.templates.StronglyEntanglingLayers,
          hamiltonian1,
          dev,
          optimize=True,
          interface="tf",
          diff_method="parameter-shift",
      )
      cost2 = catch_warn_ExpvalCost(
          qml.templates.StronglyEntanglingLayers,
          hamiltonian2,
          dev,
          optimize=False,
          interface="tf",
          diff_method="parameter-shift",
      )
  
      np.random.seed(1967)
      shape = qml.templates.StronglyEntanglingLayers.shape(
          n_layers=2, n_wires=4
      )
      w = np.random.random(shape)
  
      with qml.Tracker(dev) as tracker:
          c1 = cost(w)
      exec_opt = tracker.totals["executions"]
  
      with tracker:
          c2 = cost2(w)
      exec_no_opt = tracker.totals["executions"]
  
      assert exec_opt == 5  # Number of groups in the Hamiltonian
      assert exec_no_opt == 15
  
      assert np.allclose(c1, c2, atol=1e-1)
  
imports: import copy
  import numpy
  import pytest
  import pennylane
  from pennylane import numpy
label_desc: Use image node_id 6 for calling the TestVQE obj's underlying member method code with example usage: obj.test_optimize_tf(shots) without return types