docstr: Test that the matrix of a Hamiltonian is correctly returned
docstr_tok: ["Test","that","the","matrix","of","a","Hamiltonian","is","correctly","returned"]
code: def test_hamiltonian_qfunc(self):
      """Test that the matrix of a Hamiltonian is correctly returned"""
  
      def ansatz(x):
          return qml.PauliZ(0) @ qml.PauliY(1) - x * qml.PauliX(1)
  
      x = 0.5
  
      with pytest.warns(
          UserWarning,
          match="the eigenvalues will be computed numerically",
      ):
          res = qml.eigvals(ansatz)(x)
  
      expected = np.linalg.eigvalsh(
          reduce(np.kron, [Z, Y]) - 0.5 * reduce(np.kron, [I, X])
      )
      assert np.allclose(res, expected)
  
imports: from functools import reduce
  import pytest
  import scipy
  from gate_data import CNOT, H, I, S, X, Y, Z
  import pennylane
  from pennylane import numpy
  from pennylane.transforms.op_transforms import OperationTransformError
label_desc: Use image node_id 11 for calling the TestSingleOperation obj's underlying member method code with example usage: obj.test_hamiltonian_qfunc() and returns: unknown