class_docstr: Tests that the Barrier gate is correct.
class_docstr_tok: ["Tests","that","the","Barrier","gate","is","correct","."]
docstr: Test that the barrier works in edge cases.
docstr_tok: ["Test","that","the","barrier","works","in","edge","cases","."]
code: def test_barrier_edge_cases(self):
      r"""Test that the barrier works in edge cases."""
  
      def qfunc():
          qml.Barrier(wires=0)
          qml.Hadamard(wires=0)
          qml.Hadamard(wires=0)
          qml.Barrier(wires=0)
          return qml.expval(qml.PauliZ(0))
  
      dev = qml.device("default.qubit", wires=3)
      qnode = qml.QNode(qfunc, dev)
      gates = qml.specs(qnode)()["resources"].gate_sizes[1]
  
      assert gates == 4
  
      optimized_qfunc = qml.compile(qfunc)
      optimized_qnode = qml.QNode(optimized_qfunc, dev)
      optimized_gates = qml.specs(optimized_qnode)()[
          "resources"
      ].gate_sizes[1]
  
      assert optimized_gates == 0
  
      def qfunc1():
          qml.Hadamard(wires=0)
          qml.Barrier(wires=0)
          qml.Barrier(wires=0)
          qml.Hadamard(wires=0)
  
          return qml.expval(qml.PauliZ(0))
  
      dev = qml.device("default.qubit", wires=3)
      qnode = qml.QNode(qfunc1, dev)
      gates = qml.specs(qnode)()["resources"].gate_sizes[1]
  
      assert gates == 4
  
      def qfunc2():
          qml.Hadamard(wires=0)
          qml.Barrier(only_visual=True, wires=0)
          qml.Barrier(wires=0)
          qml.Hadamard(wires=0)
  
          return qml.expval(qml.PauliZ(0))
  
      dev = qml.device("default.qubit", wires=3)
      optimized_qfunc = qml.compile(qfunc2)
      optimized_qnode = qml.QNode(optimized_qfunc, dev)
      optimized_gates = qml.specs(optimized_qnode)()[
          "resources"
      ].gate_sizes[1]
  
      assert optimized_gates == 2
  
imports: import pytest
  import numpy
  from pennylane import Snapshot
  import pennylane
label_desc: Use image node_id 3 for calling the TestBarrier obj's underlying member method code with example usage: obj.test_barrier_edge_cases() and returns: qml, qml, qml