class_docstr: Tests for integration with the PassthruQNode
docstr: Test that the device state vector can be differentiated directly
docstr_tok: ["Test","that","the","device","state","vector","can","be","differentiated","directly"]
code: def test_state_vector_differentiability(
      self, decorator, interface, tol
  ):
      """Test that the device state vector can be differentiated directly"""
      dev = qml.device("default.mixed", wires=1)
  
      @decorator
      @qml.qnode(dev, interface=interface, diff_method="backprop")
      def circuit(a):
          qml.RY(a, wires=0)
          return qml.state()
  
      a = tf.Variable(0.54, dtype=tf.complex128, trainable=True)
  
      with tf.GradientTape() as tape:
          res = circuit(a)
  
      grad = tape.jacobian(res, a)
      expected = 0.5 * np.array(
          [[-np.sin(a), np.cos(a)], [np.cos(a), np.sin(a)]]
      )
  
      assert np.allclose(grad, expected, atol=tol, rtol=0)
  
imports: import pytest
  import numpy
  import pennylane
  from pennylane import numpy
  from pennylane.devices.default_mixed import DefaultMixed
label_desc: Use image node_id 5 for calling the TestPassthruIntegration obj's underlying member method code with example usage: obj.test_state_vector_differentiability(decorator, interface, tol) and returns: qml