class_docstr: Tests for the sign_expand transform
class_docstr_tok: ["Tests","for","the","sign_expand","transform"]
docstr: Tests if wrong observables get caught in the test
docstr_tok: ["Tests","if","wrong","observables","get","caught","in","the","test"]
code: def test_hamiltonian_error(self):
      """Tests if wrong observables get caught in the test"""
  
      with pennylane.tape.QuantumTape() as tape:
          qml.expval(qml.PauliZ(0))
  
      with pytest.raises(ValueError, match=r"Passed tape must end in"):
          qml.transforms.sign_expand(tape)
  
file_path: pennylane/tests/transforms/test_sign_expand.py
imports: import functools
  import pytest
  import numpy
  import pennylane
  import pennylane.tape
label_desc: Use image node_id 6 for calling the TestSignExpand obj's underlying member method code with example usage: obj.test_hamiltonian_error() without return types