code: def test_diff_hamiltonian(symbols, geometry, h_ref_data):
      r"""Test that diff_hamiltonian returns the correct Hamiltonian."""
  
      mol = qchem.Molecule(symbols, geometry)
      args = []
      h = qchem.diff_hamiltonian(mol)(*args)
      h_ref = qml.Hamiltonian(h_ref_data[0], h_ref_data[1])
  
      assert np.allclose(
          np.sort(h.terms()[0]), np.sort(h_ref.terms()[0])
      )
      assert qml.Hamiltonian(
          np.ones(len(h.terms()[0])), h.terms()[1]
      ).compare(
          qml.Hamiltonian(
              np.ones(len(h_ref.terms()[0])), h_ref.terms()[1]
          )
      )
  
      enable_new_opmath()
      h_pl_op = qchem.diff_hamiltonian(mol)(*args)
      disable_new_opmath()
  
      wire_order = h_ref.wires
      assert not isinstance(h_pl_op, qml.Hamiltonian)
      assert np.allclose(
          qml.matrix(h_pl_op, wire_order=wire_order),
          qml.matrix(h_ref, wire_order=wire_order),
      )
  
file_path: pennylane/tests/qchem/test_hamiltonians.py
imports: import pytest
  import pennylane
  from pennylane import Identity, PauliX, PauliY, PauliZ
  from pennylane import numpy
  from pennylane import qchem
  from pennylane.operation import disable_new_opmath, enable_new_opmath
  from pennylane.fermi import from_string
label_desc: Use image node_id 3 for calling a global function with example usage: test_diff_hamiltonian(symbols, geometry, h_ref_data) without return types