def test_undo_last_transformation_and_redo(self):
trans = []
trans.append(SubstitutionTransformation({"Li":"Na"}))
trans.append(SubstitutionTransformation({"Fe":"Mn"}))
ts = TransformedStructure(self.structure, trans)
self.assertEqual("NaMnPO4", ts.final_structure.composition.reduced_formula)
ts.undo_last_transformation()
self.assertEqual("NaFePO4", ts.final_structure.composition.reduced_formula)
ts.undo_last_transformation()
self.assertEqual("LiFePO4", ts.final_structure.composition.reduced_formula)
self.assertRaises(IndexError, ts.undo_last_transformation)
ts.redo_next_transformation()
self.assertEqual("NaFePO4", ts.final_structure.composition.reduced_formula)
ts.redo_next_transformation()
self.assertEqual("NaMnPO4", ts.final_structure.composition.reduced_formula)
self.assertRaises(IndexError, ts.redo_next_transformation)