class_docstr: Tests for the basis state projector observable.
class_docstr_tok: ["Tests","for","the","basis","state","projector","observable","."]
code: def test_integration_batched_state(self, dev):
      @qml.qnode(dev)
      def circuit(x):
          qml.RX(x, wires=0)
          return qml.expval(qml.Projector([0], wires=0))
  
      x = np.array([0.4, 0.8, 1.2])
      res = circuit(x)
      assert qml.math.allclose(res, np.cos(x / 2) ** 2)
  
imports: import functools
  import pickle
  import pytest
  import numpy
  from gate_data import I, X, Y, Z, H
  import pennylane
  from pennylane.ops.qubit.observables import BasisStateProjector, StateVectorProjector
label_desc: Use image node_id 5 for calling the TestBasisStateProjector obj's underlying member method code with example usage: obj.test_integration_batched_state(dev) and returns: qml