X zconn_at for ZODB4

lib/tests/test_zodb.py

@@ -232,7 +232,7 @@ def test_deactivate_btree():
 
 
 # verify that zconn_at gives correct answer.
-@xfail(zmajor < 5, reason="zconn_at is TODO for ZODB4 and ZODB3")
+@xfail(zmajor < 4, reason="zconn_at is TODO for ZODB3")
 @func
 def test_zconn_at():
     stor = testdb.getZODBStorage()

lib/zodb.py

@@ -182,17 +182,10 @@ def zconn_at(zconn): # -> tid
 
     # ZODB4
     #
-    # Connection:
-    #     .before     !None for historic connections
-    #
-    #     ._txn_time  - if !None - set to tid of _next_ transaction
-    #                   XXX set to None initially - what to do?
-    #
-    #     # XXX do something like that ZODB5 is doing:
-    #     zconn._start = zconn._storage.lastTransaction() + 1
-    #     # XXX _and_ check out queued invalidations
+    # We rely on our patch in 4-nxd branch.
     elif zmajor == 4:
-        raise AssertionError("zconn_at: TODO: add support for ZODB4")
+        assert 'conn:at' in ZODB.nxd_patches    # XXX error message if not there
+        return zconn.at()
 
 
     # ZODB3