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

6 files changed, 51 insertions, 4 deletions

diff --git a/lib/sqlalchemy/testing/assertsql.py b/lib/sqlalchemy/testing/assertsql.py
index 8876c2304..7988b4ec9 100644
--- a/lib/sqlalchemy/testing/assertsql.py
+++ b/lib/sqlalchemy/testing/assertsql.py
@@ -388,7 +388,9 @@ def assert_engine(engine):
     orig = []
 
     @event.listens_for(engine, "before_execute")
-    def connection_execute(conn, clauseelement, multiparams, params):
+    def connection_execute(
+        conn, clauseelement, multiparams, params, execution_options
+    ):
         # grab the original statement + params before any cursor
         # execution
         orig[:] = clauseelement, multiparams, params
diff --git a/lib/sqlalchemy/testing/config.py b/lib/sqlalchemy/testing/config.py
index 140f5f782..e97821d72 100644
--- a/lib/sqlalchemy/testing/config.py
+++ b/lib/sqlalchemy/testing/config.py
@@ -150,6 +150,14 @@ class Config(object):
         cls.set_as_current(config, namespace)
 
     @classmethod
+    def pop(cls, namespace):
+        if cls._stack:
+            # a failed test w/ -x option can call reset() ahead of time
+            _current = cls._stack[-1]
+            del cls._stack[-1]
+            cls.set_as_current(_current, namespace)
+
+    @classmethod
     def reset(cls, namespace):
         if cls._stack:
             cls.set_as_current(cls._stack[0], namespace)
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:
diff --git a/lib/sqlalchemy/testing/fixtures.py b/lib/sqlalchemy/testing/fixtures.py
index e5e6c42fc..26ae221b8 100644
--- a/lib/sqlalchemy/testing/fixtures.py
+++ b/lib/sqlalchemy/testing/fixtures.py
@@ -84,6 +84,29 @@ class TestBase(object):
     #       engines.drop_all_tables(metadata, config.db)
 
 
+class FutureEngineMixin(object):
+    @classmethod
+    def setup_class(cls):
+        super_ = super(FutureEngineMixin, cls)
+        if hasattr(super_, "setup_class"):
+            super_.setup_class()
+
+        from ..future.engine import Engine
+        from sqlalchemy import testing
+
+        config._current.push_engine(Engine._future_facade(config.db), testing)
+
+    @classmethod
+    def teardown_class(cls):
+        from sqlalchemy import testing
+
+        config._current.pop(testing)
+
+        super_ = super(FutureEngineMixin, cls)
+        if hasattr(super_, "teardown_class"):
+            super_.teardown_class()
+
+
 class TablesTest(TestBase):
 
     # 'once', None
diff --git a/lib/sqlalchemy/testing/suite/test_ddl.py b/lib/sqlalchemy/testing/suite/test_ddl.py
index 1f49106fb..93706338c 100644
--- a/lib/sqlalchemy/testing/suite/test_ddl.py
+++ b/lib/sqlalchemy/testing/suite/test_ddl.py
@@ -90,4 +90,8 @@ class TableDDLTest(fixtures.TestBase):
         )
 
 
-__all__ = ("TableDDLTest",)
+class FutureTableDDLTest(fixtures.FutureEngineMixin, TableDDLTest):
+    pass
+
+
+__all__ = ("TableDDLTest", "FutureTableDDLTest")
diff --git a/lib/sqlalchemy/testing/warnings.py b/lib/sqlalchemy/testing/warnings.py
index 6b42c98cb..39cffbf15 100644
--- a/lib/sqlalchemy/testing/warnings.py
+++ b/lib/sqlalchemy/testing/warnings.py
@@ -34,6 +34,13 @@ def setup_filters():
     # ignore 2.0 warnings unless we are explicitly testing for them
     warnings.filterwarnings("ignore", category=sa_exc.RemovedIn20Warning)
 
+    # ignore things that are deprecated *as of* 2.0 :)
+    warnings.filterwarnings(
+        "ignore",
+        category=sa_exc.SADeprecationWarning,
+        message=r".*\(deprecated since: 2.0\)$",
+    )
+
     try:
         import pytest
     except ImportError: