class_docstr: Test the new VQE syntax of passing the Hamiltonian as an observable.
class_docstr_tok: ["Test","the","new","VQE","syntax","of","passing","the","Hamiltonian","as","an","observable","."]
docstr: Tests the VQE gradient for a "zero" Hamiltonian.
docstr_tok: ["Tests","the","VQE","gradient","for","a","``","zero","''","Hamiltonian","."]
code: def test_grad_zero_hamiltonian(self, tol):
      """Tests the VQE gradient for a "zero" Hamiltonian."""
      dev = qml.device("default.qubit", wires=4)
      H = qml.Hamiltonian([0], [qml.PauliX(0)])
      w = pnp.array(PARAMS, requires_grad=True)
  
      @qml.qnode(dev, diff_method="parameter-shift")
      def circuit(w):
          qml.templates.StronglyEntanglingLayers(w, wires=range(4))
          return qml.expval(H)
  
      dc = qml.grad(circuit)(w)
      assert np.allclose(dc, 0, atol=tol)
  
imports: import copy
  import numpy
  import pytest
  import pennylane
  from pennylane import numpy
label_desc: Use image node_id 10 for calling the TestNewVQE obj's underlying member method code with example usage: obj.test_grad_zero_hamiltonian(tol) and returns: qml