oslo_log.fixtures should be provided via extras at runtime

[Matt Riedemann]

http://git.openstack.org/cgit/openstack/oslo.log/tree/oslo_log/fixture/logging_error.py is meant to be consumed by other projects, like nova.

Note that http://git.openstack.org/cgit/openstack/oslo.log/tree/oslo_log/fixture/logging_error.py imports fixtures but fixtures is only in oslo.log's test-requirements.txt:

http://git.openstack.org/cgit/openstack/oslo.log/tree/test-requirements.txt

Using Nova as an example, Nova would require oslo.log in requirements.txt (already does) and then could use oslo_log.fixture.logging_error in it's tests, but nova doesn't want to import fixtures at runtime to make that work.

We should move the fixtures dependency into setup.cfg using extras and then nova can require oslo.log['fixtures'] for testing, like we have in oslo.versionedobjects:

https://github.com/openstack/oslo.versionedobjects/blob/0.9.0/setup.cfg#L25

[Matt Riedemann (mriedem)]

Similar change under review for oslo.db:

https://review.openstack.org/#/c/217347/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/224261
Committed: https://git.openstack.org/cgit/openstack/oslo.log/commit/?id=362f329bcf446f02dd532995bbf95405ca2873eb
Submitter: Jenkins
Branch: master

commit 362f329bcf446f02dd532995bbf95405ca2873eb
Author: Mark Doffman <email address hidden>
Date: Thu Sep 10 14:34:43 2015 -0500

    Add optional 'fixture' dependencies.

    Add extra 'fixture' section so that projects needing to use
    oslo_log.fixture can add 'oslo.log [fixture]' to their
    requirements to install the fixture dependencies

    Closes-Bug: #1493976
    Change-Id: I67f3f59c50627a41b672928d037a7bd9997caa11