[openstack-dev] [oslo] oslo.db reset session?

Mike Bayer mbayer at redhat.com
Tue Feb 23 16:09:12 UTC 2016

On 02/23/2016 09:22 AM, Sean Dague wrote:
> With enginefascade working coming into projects, there seems to be some
> new bits around oslo.db global sessions.
> The effect of this on tests is a little problematic. Because it builds
> global state which couples between tests. I've got a review to use mysql
> connection explicitly for some Nova functional tests which correctly
> fails and exposes a bug when run individually. However, when run in a
> full test run, the global session means that it's not run against mysql,
> it's run against sqlite, and passes.
> https://review.openstack.org/#/c/283364/
> We need something that's the inverse of session.configure() -
> https://github.com/openstack/nova/blob/d8ddecf6e3ed1e8193e5f6dba910eb29bbe6dac6/nova/tests/fixtures.py#L205
> to reset the global session.
> Pointers would be welcomed.

from the oslo.db side, we have frameworks for testing that handle all of 
these details (e.g. oslo_db.sqlalchemy.test_base.DbTestCase and 
DbFixture).   I don't believe Nova uses these frameworks (I think it 
should long term), but for now the techniques used by oslo.db's 
framework should likely be used:

self.test.enginefacade = enginefacade._TestTransactionFactory(
             self.test.engine, self.test.sessionmaker, apply_global=True,


The above apply_global flag indicates that the global enginefacade 
should use this TestTransactionFactory until disposed.

> 	-Sean

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