docstr: Test that the spectra of a circuit is calculated correctly
  in the tf interface.
docstr_tok: ["Test","that","the","spectra","of","a","circuit","is","calculated","correctly","in","the","tf","interface","."]
code: def test_integration_tf(self):
      """Test that the spectra of a circuit is calculated correctly
      in the tf interface."""
      import tensorflow as tf
  
      dev = qml.device("default.qubit", wires=3)
      qnode = qml.QNode(circuit9, dev)
  
      x = tf.Variable([1.0, 2.0, 3.0])
      w = tf.constant([[-1, -2, -3], [-4, -5, -6]], dtype=float)
      res = qnode_spectrum(qnode, argnum=[0])(x, w)
  
      assert res
      assert res == expected_result
  
imports: from collections import OrderedDict
  import numpy
  import pytest
  import pennylane
  from pennylane import numpy
  from pennylane.fourier.qnode_spectrum import _process_ids, qnode_spectrum
  from pennylane.measurements import SampleMP, StateMP, VarianceMP
label_desc: Use image node_id 1 for calling the TestTensorflow obj's underlying member method code with example usage: obj.test_integration_tf() without return types