Update import of declarative_base()

Resolve the following MovedIn20Warning:

  The ``declarative_base()`` function is now available as
  sqlalchemy.orm.declarative_base()

Change-Id: I5fd707c62d0bfad6e54150c4a3b87aadadbeedb3
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

oslo_db/tests/fixtures.py

@@ -112,11 +112,6 @@ class WarningsFixture(fixtures.Fixture):
             message=r'The Engine.scalar\(\) method is considered legacy .*',
             category=sqla_exc.SADeprecationWarning)
 
-        warnings.filterwarnings(
-            'once',
-            message=r'The ``declarative_base\(\)`` function is now .*',
-            category=sqla_exc.SADeprecationWarning)
-
         # ...plus things that aren't our fault
 
         # FIXME(stephenfin): These are caused by sqlalchemy-migrate, not us,

oslo_db/tests/sqlalchemy/test_async_eventlet.py

@@ -20,7 +20,7 @@ import unittest
 
 from oslo_utils import importutils
 import sqlalchemy as sa
-from sqlalchemy.ext import declarative as sa_decl
+from sqlalchemy import orm
 
 from oslo_db import exception as db_exc
 from oslo_db.sqlalchemy import models
@@ -32,7 +32,7 @@ class EventletTestMixin(object):
     def setUp(self):
         super(EventletTestMixin, self).setUp()
 
-        BASE = sa_decl.declarative_base()
+        BASE = orm.declarative_base()
 
         class TmpTable(BASE, models.ModelBase):
             __tablename__ = 'test_async_eventlet'

oslo_db/tests/sqlalchemy/test_exc_filters.py

@@ -22,7 +22,7 @@ import sqlalchemy as sqla
 from sqlalchemy.engine import url as sqla_url
 from sqlalchemy import event
 import sqlalchemy.exc
-from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import declarative_base
 from sqlalchemy.orm import mapper
 from sqlalchemy import sql
 

oslo_db/tests/sqlalchemy/test_migrations.py

@@ -19,7 +19,7 @@ from unittest import mock
 import fixtures
 from migrate.versioning import api as versioning_api
 import sqlalchemy as sa
-import sqlalchemy.ext.declarative as sa_decl
+from sqlalchemy import orm
 
 from oslo_db import exception as exc
 from oslo_db.sqlalchemy import test_migrations as migrate
@@ -215,7 +215,7 @@ class ModelsMigrationSyncMixin(db_test_base._DbTestCase):
             sa.UniqueConstraint('spam', 'eggs', name='uniq_cons'),
         )
 
-        BASE = sa_decl.declarative_base(metadata=self.metadata)
+        BASE = orm.declarative_base(metadata=self.metadata)
 
         class TestModel(BASE):
             __tablename__ = 'testtbl'

oslo_db/tests/sqlalchemy/test_models.py

@@ -20,7 +20,7 @@ from unittest import mock
 from sqlalchemy import Column
 from sqlalchemy import Integer, String
 from sqlalchemy import event
-from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import declarative_base
 
 from oslo_db.sqlalchemy import models
 from oslo_db.tests import base as test_base

oslo_db/tests/sqlalchemy/test_sqlalchemy.py

@@ -28,7 +28,7 @@ from sqlalchemy import sql
 from sqlalchemy import Column, MetaData, Table
 from sqlalchemy.engine import url
 from sqlalchemy import Integer, String
-from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import declarative_base
 
 from oslo_db import exception
 from oslo_db import options as db_options

oslo_db/tests/sqlalchemy/test_types.py

@@ -14,7 +14,7 @@
 
 from sqlalchemy import Column, Integer
 from sqlalchemy.dialects import mysql
-from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import declarative_base
 
 from oslo_db import exception as db_exc
 from oslo_db.sqlalchemy import models

oslo_db/tests/sqlalchemy/test_update_match.py

@@ -10,8 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-
-from sqlalchemy.ext import declarative
+from sqlalchemy import orm
 from sqlalchemy import schema
 from sqlalchemy import sql
 from sqlalchemy import types as sqltypes
@@ -20,7 +19,7 @@ from oslo_db.sqlalchemy import update_match
 from oslo_db.tests import base as test_base
 from oslo_db.tests.sqlalchemy import base as db_test_base
 
-Base = declarative.declarative_base()
+Base = orm.declarative_base()
 
 
 class MyModel(Base):

oslo_db/tests/sqlalchemy/test_utils.py

@@ -26,8 +26,8 @@ from sqlalchemy import ForeignKey, ForeignKeyConstraint
 from sqlalchemy.dialects.postgresql import psycopg2
 from sqlalchemy.engine import url as sa_url
 from sqlalchemy.exc import OperationalError
-from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.ext.hybrid import hybrid_property
+from sqlalchemy.orm import declarative_base
 from sqlalchemy.orm import mapper
 from sqlalchemy.orm import Session
 from sqlalchemy import PrimaryKeyConstraint