class_docstr: Tests for the sample function
class_docstr_tok: ["Tests","for","the","sample","function"]
docstr: Test that a UserWarning is raised if the provided
  argument might not be hermitian.
docstr_tok: ["Test","that","a","UserWarning","is","raised","if","the","provided","argument","might","not","be","hermitian","."]
code: def test_not_an_observable(self, mocker):
      """Test that a UserWarning is raised if the provided
      argument might not be hermitian."""
      dev = qml.device("default.qubit.legacy", wires=2, shots=10)
      spy = mocker.spy(qml.QubitDevice, "sample")
  
      @qml.qnode(dev)
      def circuit():
          qml.RX(0.52, wires=0)
          return qml.sample(qml.prod(qml.PauliX(0), qml.PauliZ(0)))
  
      with pytest.warns(
          UserWarning, match="Prod might not be hermitian."
      ):
          _ = circuit()
  
      custom_measurement_process(dev, spy)
  
imports: import numpy
  import pytest
  import pennylane
  from pennylane.measurements import MeasurementShapeError, Sample, Shots, MeasurementValue
  from pennylane.operation import Operator
label_desc: Use image node_id 9 for calling the TestSample obj's underlying member method code with example usage: obj.test_not_an_observable(mocker) and returns: qml