class_docstr: Integration tests for classical shadows class
docstr: Testing the output of expectation values match those of exact evaluation
code: def test_pauli_string_expval(self, shadow):
      """Testing the output of expectation values match those of exact evaluation"""
  
      o1 = qml.PauliX(0)
      res1 = shadow.expval(o1, k=2)
  
      o2 = qml.PauliX(0) @ qml.PauliX(1)
      res2 = shadow.expval(o2, k=2)
  
      res_exact = 1.0
      assert qml.math.allclose(res1, res_exact, atol=1e-1)
      assert qml.math.allclose(res2, res_exact, atol=1e-1)
  
imports: import pytest
  import numpy
  import pennylane
  import pennylane.numpy
  from pennylane.shadows import ClassicalShadow, median_of_means, pauli_expval
label_desc: Use image node_id 1 for calling the TestIntegrationShadows obj's underlying member method code with example usage: obj.test_pauli_string_expval(shadow) without return types