def test_redo_last(self): history = UndoHistory() self._populate_history(history) history.undo() with self.assertTraitChanges(history, 'redoable', count=1): with self.assertTraitDoesNotChange(history, 'undoable'): with self.assertTraitChanges(self._example, 'anytrait', count=1): # noqa: E501 history.redo() self.assertEqual(history.now, 3) self.assertTrue(history.can_undo) self.assertFalse(history.can_redo)