<s> import alembic <EOL> from nailgun . db import dropdb <EOL> from nailgun . db . migration import ALEMBIC_CONFIG <EOL> from nailgun . test import base <EOL> class TestDbMigrations ( base . BaseTestCase ) : <EOL> def test_clean_downgrade ( self ) : <EOL> dropdb ( ) <EOL> alembic . command . upgrade ( ALEMBIC_CONFIG , '<STR_LIT>' ) <EOL> alembic . command . downgrade ( ALEMBIC_CONFIG , '<STR_LIT>' ) </s>
