fully implement future engine and remove legacy

The major action here is to lift and move future.Connection
and future.Engine fully into sqlalchemy.engine.base.   This
removes lots of engine concepts, including:

* autocommit
* Connection running without a transaction, autobegin
  is now present in all cases
* most "autorollback" is obsolete
* Core-level subtransactions (i.e. MarkerTransaction)
* "branched" connections, copies of connections
* execution_options() returns self, not a new connection
* old argument formats, distill_params(), simplifies calling
  scheme between engine methods
* before/after_execute() events (oriented towards compiled constructs)
  don't emit for exec_driver_sql().  before/after_cursor_execute()
  is still included for this
* old helper methods superseded by context managers, connection.transaction(),
  engine.transaction() engine.run_callable()
* ancient engine-level reflection methods has_table(), table_names()
* sqlalchemy.testing.engines.proxying_engine

References: #7257

Change-Id: Ib20ed816642d873b84221378a9ec34480e01e82c

1 files changed, 2 insertions, 24 deletions

diff --git a/lib/sqlalchemy/testing/fixtures.py b/lib/sqlalchemy/testing/fixtures.py
index f04056c5e..1899e5b7c 100644
--- a/lib/sqlalchemy/testing/fixtures.py
+++ b/lib/sqlalchemy/testing/fixtures.py
@@ -5,7 +5,6 @@
 # This module is part of SQLAlchemy and is released under
 # the MIT License: https://www.opensource.org/licenses/mit-license.php
 
-import contextlib
 import re
 import sys
 
@@ -93,9 +92,7 @@ class TestBase(object):
 
     @config.fixture()
     def future_engine(self):
-        eng = getattr(self, "bind", None) or config.db
-        with _push_future_engine(eng):
-            yield
+        yield
 
     @config.fixture()
     def testing_engine(self):
@@ -114,7 +111,6 @@ class TestBase(object):
             return engines.testing_engine(
                 url=url,
                 options=options,
-                future=future,
                 asyncio=asyncio,
                 transfer_staticpool=transfer_staticpool,
             )
@@ -303,26 +299,8 @@ class TestBase(object):
 _connection_fixture_connection = None
 
 
-@contextlib.contextmanager
-def _push_future_engine(engine):
-
-    from ..future.engine import Engine
-    from sqlalchemy import testing
-
-    facade = Engine._future_facade(engine)
-    config._current.push_engine(facade, testing)
-
-    yield facade
-
-    config._current.pop(testing)
-
-
 class FutureEngineMixin(object):
-    @config.fixture(autouse=True, scope="class")
-    def _push_future_engine(self):
-        eng = getattr(self, "bind", None) or config.db
-        with _push_future_engine(eng):
-            yield
+    """alembic's suite still using this"""
 
 
 class TablesTest(TestBase):