The Python version of PickleCache.minimize does what the C version does and...

The Python version of PickleCache.minimize does what the C version does and ghosts the evicted objects.

persistent/picklecache.py

@@ -293,6 +293,9 @@ class PickleCache(object):
         while node is not self.ring and self.non_ghost_count > target:
             if node.object._p_state not in (STICKY, CHANGED):
                 node.prev.next, node.next.prev = node.next, node.prev
+                # sweeping an object out of the cache should also
+                # ghost it---that's what C does
+                node.object._p_deactivate()
                 node.object = None
                 self.non_ghost_count -= 1
             node = node.next

persistent/tests/test_picklecache.py

@@ -549,6 +549,22 @@ class PickleCacheTests(unittest.TestCase):
         for oid in oids:
             self.assertTrue(cache.get(oid) is None)
 
+    def test_minimize_turns_into_ghosts(self):
+        import gc
+        from persistent.interfaces import UPTODATE
+        from persistent._compat import _b
+        cache = self._makeOne()
+        oid = _b('oid_%04d' % 1)
+        obj = cache[oid] = self._makePersist(oid=oid, state=UPTODATE)
+        self.assertEqual(cache.cache_non_ghost_count, 1)
+
+        cache.minimize()
+        gc.collect() # banish the ghosts who are no longer in the ring
+
+        self.assertEqual(cache.cache_non_ghost_count, 0)
+
+        self.assertEqual(obj._p_state, -1)
+
     def test_new_ghost_non_persistent_object(self):
         from persistent._compat import _b
         cache = self._makeOne()
@@ -849,6 +865,8 @@ class DummyPersistent(object):
         from persistent.interfaces import GHOST
         self._p_state = GHOST
 
+    _p_deactivate = _p_invalidate
+
     def _p_activate(self):
         from persistent.interfaces import UPTODATE
         self._p_state = UPTODATE