def test_full_sweep_clears_weakrefs_in_interface(self, sweep_method='full_sweep'):
# https://github.com/zopefoundation/persistent/issues/149
# Sweeping the cache clears weak refs (for PyPy especially)
# In the real world, this shows up in the interaction with
# persistent objects and zope.interface/zope.component,
# so we use an Interface to demonstrate. This helps find issues
# like needing to run GC more than once, etc, because of how the
# object is referenced.
from zope.interface import Interface
gc.disable()
self.addCleanup(gc.enable)
jar = ClosedConnection(self)
cache = self._makeOne(jar, 0)
# Make a persistent object, put it in the cache as saved
class P(self._getRealPersistentClass()):
"A real persistent object that can be weak referenced"
p = P()
p._p_jar = jar
p._p_oid = b'\x01' * 8
cache[p._p_oid] = p
p._p_changed = False
# Now, take a weak reference to it from somewhere far away.
Interface.subscribe(p)
# Remove the original object
del p
# Sweep the cache.
getattr(cache, sweep_method)()
# Now, try to use that weak reference. If the weak reference is
# still around, this will raise the error about the connection
# being closed.
Interface.changed(None)
