assertEquals(_access.get(target, "retainedValue"), "some retained value");
// Setting a property value before pageDidLoad will cause that value
// to be the default when the page detaches.
target.containingPageDidLoad();
_access.set(target, "value", "some transient value");
assertEquals(_access.get(target, "value"), "some transient value");
target.containingPageDidDetach();