class_docstr: Test that differentiating edge case tapes with ``pulse_odegen`` works.
class_docstr_tok: ["Test","that","differentiating","edge","case","tapes","with","``","pulse_odegen","``","works","."]
docstr: Test that the correct ouput and warning is generated in the absence of any trainable
  parameters with multiple returns.
docstr_tok: ["Test","that","the","correct","ouput","and","warning","is","generated","in","the","absence","of","any","trainable","parameters","with","multiple","returns","."]
code: def test_no_trainable_params_multiple_return_tape(self):
      """Test that the correct ouput and warning is generated in the absence of any trainable
      parameters with multiple returns."""
      dev = qml.device("default.qubit", wires=2)
  
      weights = [0.1, 0.2]
      with qml.queuing.AnnotatedQueue() as q:
          qml.RX(weights[0], wires=0)
          qml.RY(weights[1], wires=0)
          qml.expval(Z(0) @ Z(1))
          qml.probs(wires=[0, 1])
  
      tape = qml.tape.QuantumScript.from_queue(q)
      tape.trainable_params = []
  
      with pytest.warns(
          UserWarning,
          match="gradient of a tape with no trainable parameters",
      ):
          _tapes, fn = pulse_odegen(tape)
      res = fn(dev.execute(_tapes))
  
      assert _tapes == []
      assert isinstance(res, tuple)
      for r in res:
          assert isinstance(r, np.ndarray)
          assert r.shape == (0,)
  
imports: import copy
  import pytest
  import numpy
  import pennylane
  from pennylane import numpy
  from pennylane.ops.qubit.special_unitary import pauli_basis_matrices, pauli_basis_strings
  from pennylane.math import expand_matrix
  from pennylane.gradients.pulse_gradient_odegen import _generate_tapes_and_coeffs, pulse_odegen, _insert_op, _nonzero_coeffs_and_words, _one_parameter_generators, _one_parameter_paulirot_coeffs, _parshift_and_contract
label_desc: Use image node_id 6 for calling the TestPulseOdegenEdgeCases obj's underlying member method code with example usage: obj.test_no_trainable_params_multiple_return_tape() without return types