use code generation for scoped_session

our decorator thing generates code in any case,
so point it at the file itself to generate real code
for the blocks rather than doing things dynamically.

this will allow typing tools to have no problem
whatsoever and we also reduce import time overhead.
file size will be a lot bigger though, shrugs.

syntax / dupe method / etc. checking will be accomplished
by our existing linting / typing / formatting tools.

As we are also using "from __future__ import annotations",
we also no longer have to apply quotes to generated
annotations.

Change-Id: I20962cb65bda63ff0fb67357ab346e9b1ef4f108

2 files changed, 22 insertions, 13 deletions

diff --git a/lib/sqlalchemy/testing/plugin/plugin_base.py b/lib/sqlalchemy/testing/plugin/plugin_base.py
index 52e42bb97..b90858512 100644
--- a/lib/sqlalchemy/testing/plugin/plugin_base.py
+++ b/lib/sqlalchemy/testing/plugin/plugin_base.py
@@ -5,14 +5,8 @@
 # This module is part of SQLAlchemy and is released under
 # the MIT License: https://www.opensource.org/licenses/mit-license.php
 
-"""Testing extensions.
-
-this module is designed to work as a testing-framework-agnostic library,
-created so that multiple test frameworks can be supported at once
-(mostly so that we can migrate to new ones). The current target
-is pytest.
+from __future__ import annotations
 
-"""
 import abc
 import configparser
 import logging
@@ -23,6 +17,15 @@ from typing import Any
 
 from sqlalchemy.testing import asyncio
 
+"""Testing extensions.
+
+this module is designed to work as a testing-framework-agnostic library,
+created so that multiple test frameworks can be supported at once
+(mostly so that we can migrate to new ones). The current target
+is pytest.
+
+"""
+
 # flag which indicates we are in the SQLAlchemy testing suite,
 # and not that of Alembic or a third party dialect.
 bootstrapped_as_sqlalchemy = False
diff --git a/lib/sqlalchemy/testing/plugin/pytestplugin.py b/lib/sqlalchemy/testing/plugin/pytestplugin.py
index 6efeac504..ab93e60e2 100644
--- a/lib/sqlalchemy/testing/plugin/pytestplugin.py
+++ b/lib/sqlalchemy/testing/plugin/pytestplugin.py
@@ -1,9 +1,4 @@
-try:
-    # installed by bootstrap.py
-    import sqla_plugin_base as plugin_base
-except ImportError:
-    # assume we're a package, use traditional import
-    from . import plugin_base
+from __future__ import annotations
 
 import argparse
 import collections
@@ -17,6 +12,13 @@ import uuid
 
 import pytest
 
+try:
+    # installed by bootstrap.py
+    import sqla_plugin_base as plugin_base
+except ImportError:
+    # assume we're a package, use traditional import
+    from . import plugin_base
+
 
 def pytest_addoption(parser):
     group = parser.getgroup("sqlalchemy")
@@ -565,6 +567,10 @@ def _pytest_fn_decorator(target):
     from sqlalchemy.util.compat import inspect_getfullargspec
 
     def _exec_code_in_env(code, env, fn_name):
+        # note this is affected by "from __future__ import annotations" at
+        # the top; exec'ed code will use non-evaluated annotations
+        # which allows us to be more flexible with code rendering
+        # in format_argpsec_plus()
         exec(code, env)
         return env[fn_name]