DemoStorage: add support for conflict resolution

src/ZODB/ConflictResolution.py

@@ -313,4 +313,9 @@ class ConflictResolvingStorage(object):
     def registerDB(self, wrapper):
         self._crs_untransform_record_data = wrapper.untransform_record_data
         self._crs_transform_record_data = wrapper.transform_record_data
-        super(ConflictResolvingStorage, self).registerDB(wrapper)
+        try:
+            m = super(ConflictResolvingStorage, self).registerDB
+        except AttributeError:
+            pass
+        else:
+            m(wrapper)

src/ZODB/DemoStorage.py

@@ -31,12 +31,13 @@ import ZODB.MappingStorage
 import ZODB.POSException
 import ZODB.utils
 import zope.interface
+from .ConflictResolution import ConflictResolvingStorage, ResolvedSerial
 
 @zope.interface.implementer(
         ZODB.interfaces.IStorage,
         ZODB.interfaces.IStorageIteration,
         )
-class DemoStorage(object):
+class DemoStorage(ConflictResolvingStorage):
 
 
     def __init__(self, name=None, base=None, changes=None,
@@ -112,7 +113,7 @@ class DemoStorage(object):
     def _copy_methods_from_changes(self, changes):
         for meth in (
             '_lock_acquire', '_lock_release',
-            'getSize', 'history', 'isReadOnly', 'registerDB',
+            'getSize', 'history', 'isReadOnly',
             'sortKey', 'tpc_transaction', 'tpc_vote',
             ):
             setattr(self, meth, getattr(changes, meth))
@@ -281,8 +282,9 @@ class DemoStorage(object):
                 old = serial
 
         if old != serial:
-            raise ZODB.POSException.ConflictError(
-                oid=oid, serials=(old, serial)) # XXX untested branch
+            rdata = self.tryToResolveConflict(oid, old, serial, data)
+            self.changes.store(oid, old, rdata, '', transaction)
+            return ResolvedSerial
 
         return self.changes.store(oid, serial, data, '', transaction)
 

src/ZODB/tests/testDemoStorage.py

@@ -14,6 +14,7 @@
 from ZODB.DB import DB
 from ZODB.tests import (
     BasicStorage,
+    ConflictResolution,
     HistoryStorage,
     IteratorStorage,
     MTStorage,
@@ -42,7 +43,7 @@ from zope.testing import renormalizing
 class DemoStorageTests(
     StorageTestBase.StorageTestBase,
     BasicStorage.BasicStorage,
-
+    ConflictResolution.ConflictResolvingStorage,
     HistoryStorage.HistoryStorage,
     IteratorStorage.ExtendedIteratorStorage,
     IteratorStorage.IteratorStorage,
@@ -144,11 +145,11 @@ def testSomeDelegation():
     >>> class S:
     ...     def __init__(self, name):
     ...         self.name = name
-    ...     def registerDB(self, db):
-    ...         six.print_(self.name, db)
+    ...     def getSize(self):
+    ...         six.print_(self.name, 'size')
     ...     def close(self):
     ...         six.print_(self.name, 'closed')
-    ...     sortKey = getSize = __len__ = history = getTid = None
+    ...     sortKey = __len__ = history = getTid = None
     ...     tpc_finish = tpc_vote = tpc_transaction = None
     ...     _lock_acquire = _lock_release = lambda self: None
     ...     getName = lambda self: 'S'
@@ -165,8 +166,8 @@ def testSomeDelegation():
     >>> from ZODB.DemoStorage import DemoStorage
     >>> storage = DemoStorage(base=S(1), changes=S(2))
 
-    >>> storage.registerDB(1)
-    2 1
+    >>> storage.getSize()
+    2 size
 
     >>> storage.close()
     1 closed