.

lib/tests/test_zodb.py

@@ -17,13 +17,15 @@
 #
 # See COPYING file for full licensing terms.
 # See https://www.nexedi.com/licensing for rationale and options.
-from wendelin.lib.zodb import LivePersistent, deactivate_btree, dbclose
+from wendelin.lib.zodb import LivePersistent, deactivate_btree, dbclose, zconn_at
 from wendelin.lib.testing import getTestDB
 from persistent import Persistent, UPTODATE, GHOST, CHANGED
+from ZODB import DB, POSException
 from BTrees.IOBTree import IOBTree
 import transaction
 from transaction import TransactionManager
 from golang import defer, func
+from pytest import raises
 import gc
 
 testdb = None
@@ -228,7 +230,46 @@ def test_deactivate_btree():
             assert obj not in cached
 
 
+# zsync syncs ZODB storage.
+# it is noop, if zstor does not support syncing (i.e. FileStorage has no .sync())
+def zsync(zstor):
+    sync = getattr(zstor, 'sync', None)
+    if sync is not None:
+        sync()
+
+@func
 def test_zconn_at():
+    stor = testdb.getZODBStorage()
+    defer(stor.close)
+    db  = DB(stor)
+
+    zsync(stor)
+    at0 = stor.lastTransaction()
+
+    # open connection, it must be viewing the database @at0
+    conn1 = db.open()
+    assert zconn_at(conn1) == at0
+
+    # commit
+    root1 = conn1.root()
+    root1['z'] = 1
+    transaction.commit()
+
+    # after commit the view is updated
+    zsync(stor)
+    at1 = stor.lastTransaction()
+    assert zconn_at(conn1) == at1   # still at at0  XXX ok?
+
+    # reopen -> view @at1
+    conn1.close()
+    with raises(POSException.ConnectionStateError):
+        zconn_at(conn1)
+    conn2 = db.open()
+    assert conn2 is conn1   # returned from DB pool
+    assert zconn_at(conn2) == at1
+    conn2.close()
+
+
     # TODO commit -> know head -> open conn1,
     #      open conn2, commit there; wait or sync, make sure zconn_at(conn1) is as expected
 

lib/zodb.py

@@ -22,6 +22,7 @@
 import ZODB
 from ZODB.FileStorage import FileStorage
 from ZODB import DB
+from ZODB import POSException
 from ZODB.utils import p64, u64
 from persistent import Persistent
 from weakref import WeakSet
@@ -141,7 +142,8 @@ def _deactivate_bucket(bucket):
 # zconn_at returns tid as of which ZODB connection is viewing the database.
 def zconn_at(zconn): # -> tid
     assert isinstance(zconn, ZODB.Connection.Connection)
-    # XXX assert zconn is opened
+    if zconn.opened is None: # zconn must be in "opened" state
+        raise POSException.ConnectionStateError("database connection is closed")
 
     # ZODB5 uses MVCC uniformly
     if zmajor >= 5: