class_docstr: Tests for the helper method _split_evol_ops that samples a splitting time and splits up
  a ParametrizedEvolution operation at the sampled time, inserting a Pauli rotation about the
  provided Pauli word with angles +- pi/2.
class_docstr_tok: ["Tests","for","the","helper","method","_split_evol_ops","that","samples","a","splitting","time","and","splits","up","a","ParametrizedEvolution","operation","at","the","sampled","time",",","inserting","a","Pauli","rotation","about","the","provided","Pauli","word","with","angles","+-","pi\/2","."]
docstr: Test that a warning is raised for computing eigenvalues of a Hamiltonian
  for more than four wires but not for fewer wires.
docstr_tok: ["Test","that","a","warning","is","raised","for","computing","eigenvalues","of","a","Hamiltonian","for","more","than","four","wires","but","not","for","fewer","wires","."]
code: def test_warnings(self):
      """Test that a warning is raised for computing eigenvalues of a Hamiltonian
      for more than four wires but not for fewer wires."""
      import jax
  
      jax.config.update("jax_enable_x64", True)
      ham = qml.pulse.constant * qml.PauliY(0)
      op = qml.evolve(ham)([0.3], 2.0)
      ob = qml.Hamiltonian(
          [0.4, 0.2],
          [
              qml.operation.Tensor(*[qml.PauliY(i) for i in range(5)]),
              qml.PauliX(0),
          ],
      )
      with pytest.warns(
          UserWarning,
          match="the eigenvalues will be computed numerically",
      ):
          _split_evol_ops(op, ob, tau=0.4)
  
      ob = qml.Hamiltonian(
          [0.4, 0.2],
          [
              qml.operation.Tensor(*[qml.PauliY(i) for i in range(4)]),
              qml.PauliX(0),
          ],
      )
      with warnings.catch_warnings():
          warnings.simplefilter("error")
          _split_evol_ops(op, ob, tau=0.4)
  
imports: import warnings
  import copy
  import pytest
  import numpy
  import pennylane
  from pennylane.gradients.general_shift_rules import eigvals_to_frequencies, generate_shift_rule
  from pennylane.gradients.pulse_gradient import _parshift_and_integrate, _split_evol_ops, _split_evol_tape, stoch_pulse_grad
label_desc: Use image node_id 3 for calling the TestSplitEvolOps obj's underlying member method code with example usage: obj.test_warnings() without return types