Add a test checking the non-cooperative behaviour of...

Add a test checking the non-cooperative behaviour of Persistent.__getattribute__ in both C and Python.

persistent/interfaces.py

@@ -23,7 +23,7 @@ try:
     from persistent.cPersistence import UPTODATE
     from persistent.cPersistence import CHANGED
     from persistent.cPersistence import STICKY
-except ImportError: #pragma NO COVER
+except ImportError: # pragma: no cover
     GHOST = -1
     UPTODATE = 0
     CHANGED = 1

persistent/picklecache.py

@@ -48,7 +48,7 @@ _SWEEP_NEEDS_GC = not hasattr(sys, 'getrefcount')
 
 # On Jython, we need to explicitly ask it to monitor
 # objects if we want a more deterministic GC
-if hasattr(gc, 'monitorObject'): #pragma: no cover
+if hasattr(gc, 'monitorObject'): # pragma: no cover
     _gc_monitor = gc.monitorObject
 else:
     def _gc_monitor(o):
@@ -395,7 +395,8 @@ class PickleCache(object):
         value = self.data.get(oid)
         if value is not None and value._p_state != GHOST:
             value._p_invalidate()
-            if self.ring.delete(value):
+            was_in_ring = self.ring.delete(value)
+            assert was_in_ring, "Ring corruption: invalidated a non-ghost not in ring"
             self.non_ghost_count -= 1
         elif oid in self.persistent_classes:
             persistent_class = self.persistent_classes[oid]

persistent/ring.py

@@ -146,7 +146,7 @@ class _DequeRing(object):
 
 try:
     from cffi import FFI
-except ImportError: #pragma: no cover
+except ImportError: # pragma: no cover
     _CFFIRing = None
 else:
 

persistent/tests/test_persistence.py

@@ -692,6 +692,24 @@ class _Persistent_Base(object):
         self.assertEqual(getattr(inst, 'normal', None), 'value')
         self._checkMRU(jar, [OID])
 
+    def test___getattribute___non_cooperative(self):
+        # Getting attributes is NOT cooperative with the superclass.
+        # This comes from the C implementation and is maintained
+        # for backwards compatibility. (For example, Persistent and
+        # ExtensionClass.Base/Acquisition take special care to mix together.)
+        class Base(object):
+            def __getattribute__(self, name):
+                if name == 'magic':
+                    return 42
+                return super(Base,self).__getattribute__(name)
+
+        self.assertEqual(getattr(Base(), 'magic'), 42)
+
+        class Derived(self._getTargetClass(), Base):
+            pass
+
+        self.assertRaises(AttributeError, getattr, Derived(), 'magic')
+
     def test___setattr___p__names(self):
         from persistent.timestamp import _makeOctets
         SERIAL = _makeOctets('\x01' * 8)