Move baremetal database tests to fixtures.

The baremetal database tests didn't get migrated to fixtures when we migrated
base nova. Funny story: maybe we should re-use code rather than copying!

So I did that. It's reusable now.

Change-Id: I730aad4a6aedb3993e032a14c9b8d2cd58913b4f

nova/tests/baremetal/db/base.py

@@ -15,31 +15,25 @@
 
 """Bare-metal DB test base class."""
 
+import fixtures
+
 from nova import context as nova_context
 from nova.openstack.common import cfg
 from nova import test
 from nova.virt.baremetal.db import migration as bm_migration
 from nova.virt.baremetal.db.sqlalchemy import session as bm_session
 
-_DB = None
+_DB_CACHE = None
 
 CONF = cfg.CONF
 CONF.import_opt('baremetal_sql_connection',
                 'nova.virt.baremetal.db.sqlalchemy.session')
 
 
-def _reset_bmdb():
-    global _DB
-    engine = bm_session.get_engine()
-    engine.dispose()
-    conn = engine.connect()
-    if _DB is None:
-        if bm_migration.db_version() > bm_migration.INIT_VERSION:
-            return
-        bm_migration.db_sync()
-        _DB = "".join(line for line in conn.connection.iterdump())
-    else:
-        conn.connection.executescript(_DB)
+class Database(test.Database):
+
+    def post_migrations(self):
+        pass
 
 
 class BMDBTestCase(test.TestCase):
@@ -47,5 +41,8 @@ class BMDBTestCase(test.TestCase):
     def setUp(self):
         super(BMDBTestCase, self).setUp()
         self.flags(baremetal_sql_connection='sqlite:///:memory:')
-        _reset_bmdb()
+        global _DB_CACHE
+        if not _DB_CACHE:
+            _DB_CACHE = Database(bm_session, bm_migration)
+        self.useFixture(_DB_CACHE)
         self.context = nova_context.get_admin_context()