extract RPC setup into a fixture

This extracts the common RPC setup into a fixture. Eventually we need
to get this fixture off the base setup as < 5% of tests actually use
the RPC infrastructure today (probably more than half of those are
using it by accident due to insufficient mocking), and only 3 cells
tests actually need the exmods setting.

This moves the ball forward slightly towards getting there.

part of bp:functional-tests-for-nova

Change-Id: I7ab9f7f0615c137025aa07e4113e0d207d36a4c5

nova/test.py

@@ -33,7 +33,6 @@ import os
 import fixtures
 from oslo.config import cfg
 from oslo.config import fixture as config_fixture
-from oslo.messaging import conffixture as messaging_conffixture
 from oslo.utils import timeutils
 from oslo_concurrency import lockutils
 from oslotest import moxstubout
@@ -48,7 +47,6 @@ from nova import objects
 from nova.objects import base as objects_base
 from nova.openstack.common.fixture import logging as log_fixture
 from nova.openstack.common import log as nova_logging
-from nova import rpc
 from nova.tests import fixtures as nova_fixtures
 from nova.tests.unit import conf_fixture
 from nova.tests.unit import policy_fixture
@@ -208,10 +206,6 @@ class TestCase(testtools.TestCase):
 
         self.useFixture(nova_fixtures.StandardLogging())
 
-        rpc.add_extra_exmods('nova.test')
-        self.addCleanup(rpc.clear_extra_exmods)
-        self.addCleanup(rpc.cleanup)
-
         # NOTE(sdague): because of the way we were using the lock
         # wrapper we eneded up with a lot of tests that started
         # relying on global external locking being set up for them. We
@@ -231,12 +225,7 @@ class TestCase(testtools.TestCase):
                                 group='oslo_concurrency')
 
         self.useFixture(conf_fixture.ConfFixture(CONF))
-
-        self.messaging_conf = messaging_conffixture.ConfFixture(CONF)
-        self.messaging_conf.transport_driver = 'fake'
-        self.useFixture(self.messaging_conf)
-
-        rpc.init(CONF)
+        self.useFixture(nova_fixtures.RPCFixture('nova.test'))
 
         if self.USES_DB:
             self.useFixture(nova_fixtures.Database())

nova/tests/fixtures.py

@@ -24,8 +24,9 @@ import uuid
 
 import fixtures
 from oslo.config import cfg
-
+from oslo.messaging import conffixture as messaging_conffixture
 from nova.db import migration
+from nova import rpc
 from nova.db.sqlalchemy import api as session
 from nova import service
 
@@ -217,3 +218,20 @@ class Database(fixtures.Fixture):
     def setUp(self):
         super(Database, self).setUp()
         self.reset()
+
+
+class RPCFixture(fixtures.Fixture):
+    def __init__(self, *exmods):
+        super(RPCFixture, self).__init__()
+        self.exmods = []
+        self.exmods.extend(exmods)
+
+    def setUp(self):
+        super(RPCFixture, self).setUp()
+        self.addCleanup(rpc.cleanup)
+        rpc.add_extra_exmods(*self.exmods)
+        self.addCleanup(rpc.clear_extra_exmods)
+        self.messaging_conf = messaging_conffixture.ConfFixture(CONF)
+        self.messaging_conf.transport_driver = 'fake'
+        self.useFixture(self.messaging_conf)
+        rpc.init(CONF)