generalize scoped_session proxying and apply to asyncio elements

Reworked the proxy creation used by scoped_session() to be
based on fully copied code with augmented docstrings and
moved it into langhelpers.  asyncio session, engine,
connection can now take
advantage of it so that all non-async methods are availble.

Overall implementation of most important accessors / methods
on AsyncConnection, etc. , including awaitable versions
of invalidate, execution_options, etc.

In order to support an event dispatcher on the async
classes while still allowing them to hold __slots__,
make some adjustments to the event system to allow
that to be present, at least rudimentally.

Fixes: #5628
Change-Id: I5eb6929fc1e4fdac99e4b767dcfd49672d56e2b2

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/sqlalchemy/testing/plugin/pytestplugin.py b/lib/sqlalchemy/testing/plugin/pytestplugin.py
index dfefd3b95..644ea6dc2 100644
--- a/lib/sqlalchemy/testing/plugin/pytestplugin.py
+++ b/lib/sqlalchemy/testing/plugin/pytestplugin.py
@@ -372,7 +372,7 @@ def _pytest_fn_decorator(target):
         if add_positional_parameters:
             spec.args.extend(add_positional_parameters)
 
-        metadata = dict(target="target", fn="fn", name=fn.__name__)
+        metadata = dict(target="target", fn="__fn", name=fn.__name__)
         metadata.update(format_argspec_plus(spec, grouped=False))
         code = (
             """\
@@ -382,7 +382,7 @@ def %(name)s(%(args)s):
             % metadata
         )
         decorated = _exec_code_in_env(
-            code, {"target": target, "fn": fn}, fn.__name__
+            code, {"target": target, "__fn": fn}, fn.__name__
         )
         if not add_positional_parameters:
             decorated.__defaults__ = getattr(fn, "__func__", fn).__defaults__