Add some simple synchronization sanity tests

src/ZODB/tests/Synchronization.py

+"""Test the storage's implemenetation of the storage synchronization spec.
+
+The Synchronization spec
+    http://www.zope.org/Documentation/Developer/Models/ZODB/
+    ZODB_Architecture_Storage_Interface_State_Synchronization_Diag.html
+
+It specifies two states committing and non-committing.  A storage
+starts in the non-committing state.  tpc_begin() transfers to the
+committting state; tpc_abort() and tpc_finish() transfer back to
+non-committing.
+
+Several other methods are only allowed in one state or another.  Many
+methods allowed only in the committing state require that they apply
+to the currently committing transaction.
+
+The spec is silent on a variety of methods that don't appear to modify
+the state, e.g. load(), undoLog(), pack().  It's unclear whether there
+is a separate set of synchronization rules that apply to these methods
+or if the synchronization is implementation dependent, i.e. only what
+is need to guarantee a corrected implementation.
+
+The synchronization spec is also silent on whether there is any
+contract implied with the caller.  If the storage can assume that a
+single client is single-threaded and that it will not call, e.g., store()
+until after it calls tpc_begin(), the implementation can be
+substantially simplified.
+
+New and/or unspecified methods:
+
+tpc_vote(): handled like tpc_abort
+transactionalUndo(): handled like undo()  (which is how?)
+
+Methods that have nothing to do with committing/non-committing:
+load(), loadSerial(), getName(), getSize(), __len__(), history(),
+undoLog(), modifiedInVersion(), versionEmpty(), versions(), pack().
+
+Specific questions:
+
+The spec & docs say that undo() takes three arguments, the second
+being a transaction.  If the specified arg isn't the current
+transaction, the undo() should raise StorageTransactionError.  This
+isn't implemented anywhere.  It looks like undo can be called at
+anytime.
+
+FileStorage does not allow undo() during a pack.  How should this be
+tested?  Is it a general restriction?
+
+
+
+"""
+
+from ZODB.Transaction import Transaction
+from ZODB.POSException import StorageTransactionError
+
+VERSION = "testversion"
+OID = "\000" * 8
+SERIALNO = "\000" * 8
+TID = "\000" * 8
+
+class SynchronizedStorage:
+
+    def verifyCommitting(self, callable, *args):
+        self.assertRaises(StorageTransactionError, callable *args)
+    
+    def verifyNotCommitting(self, callable, *args):
+        self.assertRaises(StorageTransactionError, callable, *args)
+
+    def verifyWrongTrans(self, callable, *args):
+        self._storage.tpc_begin(self._transaction)
+        self.assertRaises(StorageTransactionError, callable, *args)
+
+    def checkAbortVersionNotCommitting(self):
+        self.verifyNotCommitting(self._storage.abortVersion,
+                                 VERSION, self._transaction)
+
+    def checkAbortVersionWrongTrans(self):
+        self.verifyWrongTrans(self._storage.abortVersion,
+                              VERSION, Transaction())
+
+    def checkCommitVersionNotCommitting(self):
+        self.verifyNotCommitting(self._storage.commitVersion,
+                                 VERSION, "", self._transaction)
+
+    def checkCommitVersionWrongTrans(self):
+        self.verifyWrongTrans(self._storage.commitVersion,
+                              VERSION, "", Transaction())
+
+
+    def checkStoreNotCommitting(self):
+        self.verifyNotCommitting(self._storage.store,
+                                 OID, SERIALNO, "", "", self._transaction)
+    
+    def checkStoreWrongTrans(self):
+        self.verifyWrongTrans(self._storage.store,
+                              OID, SERIALNO, "", "", Transaction())
+
+##    def checkNewOidNotCommitting(self):
+##        self.verifyNotCommitting(self._storage.new_oid)
+    
+##    def checkNewOidWrongTrans(self):
+##        self.verifyWrongTrans(self._storage.new_oid)
+    
+
+    def checkAbortNotCommitting(self):
+        self._storage.tpc_abort(Transaction())
+
+    def checkAbortWrongTrans(self):
+        self._storage.tpc_begin(self._transaction)
+        self._storage.tpc_abort(Transaction())
+
+    def checkFinishNotCommitting(self):
+        self._storage.tpc_finish(Transaction())
+
+    def checkFinishWrongTrans(self):
+        self._storage.tpc_begin(self._transaction)
+        self._storage.tpc_finish(Transaction())
+    
+    def checkBeginCommitting(self):
+        self._storage.tpc_begin(self._transaction)
+        self._storage.tpc_begin(self._transaction)
+
+    # XXX how to check undo?