Every example in this series so far has wrapped a call. A binding named a method, and what flowed through the call was recorded or changed. Plenty of what a test needs to control is not a call, though. An outcome stored in an attribute, an environment variable that must be set or missing, a settings dict that other modules imported by reference at import time, a formatter looked up in a registry, and a generator whose interesting behaviour is spread over its consumption. unittest.mock and pytest between them cover most of this with patch.dict, monkeypatch.setattr, monkeypatch.setenv and so on, one idiom per shape. wrapture spells all of them as bindings, which buys the same lifecycle everywhere, and in a couple of places lets the binding observe as well as hold.
Attribute bindings
A binding on a class attribute which is not a callable is detected as attribute mode, and instead of on_call it has on_get, on_set and on_delete, one channel per operation. Under the covers it installs a data descriptor on the class, wrapping whatever was there before, so a property's getter still runs and writes still land in the instance dictionary. Take a model with a status:
class Model:
status = "draft"
