docstr: Test that the expval estimation is correct for a QFT state
code: def test_qft_expval(self, interface):
      """Test that the expval estimation is correct for a QFT state"""
      circuit = qft_circuit(3, shots=100000, interface=interface)
      bits, recipes = circuit()
      shadow = ClassicalShadow(bits, recipes)
  
      obs = [
          qml.PauliX(0),
          qml.PauliX(0) @ qml.PauliX(1),
          qml.PauliX(0) @ qml.PauliX(2),
          qml.PauliX(0) @ qml.Identity(1) @ qml.PauliX(2),
          qml.PauliZ(2),
          qml.PauliX(1) @ qml.PauliY(2),
          qml.PauliY(1) @ qml.PauliX(2),
          qml.Identity(0) @ qml.PauliY(1) @ qml.PauliX(2),
          qml.PauliX(0) @ qml.PauliY(1) @ qml.PauliY(2),
          qml.PauliY(0) @ qml.PauliX(1) @ qml.PauliX(2),
      ]
  
      expected = [
          -1,
          0,
          -1 / np.sqrt(2),
          -1 / np.sqrt(2),
          0,
          0,
          1 / np.sqrt(2),
          1 / np.sqrt(2),
          -1 / np.sqrt(2),
          0,
      ]
  
      actual = shadow.expval(obs, k=10)
      assert actual.shape == (10,)
      assert actual.dtype == np.float64
      assert qml.math.allclose(actual, expected, 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 TestExpvalEstimationInterfaces obj's underlying member method code with example usage: obj.test_qft_expval(interface) without return types