class_docstr: Test the wire labels.
docstr: Test show_all_wires=True forces empty wires to display.
docstr_tok: ["Test","show_all_wires=True","forces","empty","wires","to","display","."]
code: def test_show_all_wires(self):
      """Test show_all_wires=True forces empty wires to display."""
  
      @qml.qnode(qml.device("default.qubit", wires=(0, 1)))
      def circ():
          return qml.expval(qml.PauliZ(0))
  
      split_str = draw(circ, show_all_wires=True)().split("\n")
      assert split_str[0][:2] == "0:"
      assert split_str[1][:2] == "1:"
  
imports: from functools import partial
  import pytest
  import pennylane
  from pennylane import numpy
  from pennylane.drawer import draw
label_desc: Use image node_id 3 for calling the TestLabelling obj's underlying member method code with example usage: obj.test_show_all_wires() and returns: qml