Surface driver connection object when using a proxied dialect

Improve the interface used by adapted drivers, like the asyncio ones,
to access the actual connection object returned by the driver.

The :class:`_engine._ConnectionRecord` and
:class:`_engine._ConnectionFairy` now have two new attributes:

* ``dbapi_connection`` always represents a DBAPI compatible
object.  For pep-249 drivers, this is the DBAPI connection as it always
has been, previously accessed under the ``.connection`` attribute.
For asyncio drivers that SQLAlchemy adapts into a pep-249 interface,
the returned object will normally be a SQLAlchemy adaption object
called :class:`_engine.AdaptedConnection`.
* ``driver_connection`` always represents the actual connection object
maintained by the third party pep-249 DBAPI or async driver in use.
For standard pep-249 DBAPIs, this will always be the same object
as that of the ``dbapi_connection``.  For an asyncio driver, it will be
the underlying asyncio-only connection object.

The ``.connection`` attribute remains available and is now a legacy alias
of ``.dbapi_connection``.

Fixes: #6832
Change-Id: Ib72f97deefca96dce4e61e7c38ba430068d6a82e

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/sqlalchemy/testing/engines.py b/lib/sqlalchemy/testing/engines.py
index 7d78dcc1a..a54f70c5e 100644
--- a/lib/sqlalchemy/testing/engines.py
+++ b/lib/sqlalchemy/testing/engines.py
@@ -65,7 +65,7 @@ class ConnectionKiller(object):
 
         for rec in list(self.proxy_refs):
             if rec is not None and rec.is_valid:
-                self.dbapi_connections.discard(rec.connection)
+                self.dbapi_connections.discard(rec.dbapi_connection)
                 self._safe(rec._checkin)
 
         # for fairy refs that were GCed and could not close the connection,