Create initial 2.0 engine implementation

Implemented the SQLAlchemy 2 :func:`.future.create_engine` function which
is used for forwards compatibility with SQLAlchemy 2.   This engine
features always-transactional behavior with autobegin.

Allow execution options per statement execution.  This includes
that the before_execute() and after_execute() events now accept
an additional dictionary with these options, empty if not
passed; a legacy event decorator is added for backwards compatibility
which now also emits a deprecation warning.

Add some basic tests for execution, transactions, and
the new result object.   Build out on a new testing fixture
that swaps in the future engine completely to start with.

Change-Id: I70e7338bb3f0ce22d2f702537d94bb249bd9fb0a
Fixes: #4644

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/sqlalchemy/testing/engines.py b/lib/sqlalchemy/testing/engines.py
index 910af5876..280e6901e 100644
--- a/lib/sqlalchemy/testing/engines.py
+++ b/lib/sqlalchemy/testing/engines.py
@@ -238,10 +238,13 @@ def reconnecting_engine(url=None, options=None):
     return engine
 
 
-def testing_engine(url=None, options=None):
+def testing_engine(url=None, options=None, future=False):
     """Produce an engine configured by --options with optional overrides."""
 
-    from sqlalchemy import create_engine
+    if future or config.db and config.db._is_future:
+        from sqlalchemy.future import create_engine
+    else:
+        from sqlalchemy import create_engine
     from sqlalchemy.engine.url import make_url
 
     if not options: