Method test_weakref

test/aaa_profiling/test_memusage.py:1784–1828

test the weak-referencing identity map, which strongly- references modified items.

(self)

    run_inserts = None

    def test_weakref(self):
        """test the weak-referencing identity map, which strongly-
        references modified items."""

        users, User = self.tables.users, self.classes.User
        self.mapper_registry.map_imperatively(User, users)

        with Session(testing.db) as s:
            gc_collect()

            s.add(User(name="ed"))
            s.flush()
            assert not s.dirty

            user = s.query(User).one()

            user_is = user._sa_instance_state
            del user
            user_is._force_dereference()

            assert len(s.identity_map) == 0

            user = s.query(User).one()
            user_is = user._sa_instance_state
            user.name = "fred"

            del user
            gc_collect()

            # object was not gc'ed
            assert user_is.obj()

            assert len(s.identity_map) == 1
            assert len(s.dirty) == 1
            assert None not in s.dirty
            s.flush()
            gc_collect()
            user_is._force_dereference()

            assert not s.dirty
            assert not s.identity_map

            user = s.query(User).one()
            assert user.name == "fred"
            assert s.identity_map

    def test_weakref_pickled(self):
        users, User = self.tables.users, pickleable.User