Add a unit testing configuration fixture1.2.0a3

The configuration options registered by oslo.messaging should not be
directly relied upon by users of the library, since those config option
names could change in future.

Add an API which allows API users to override specific configuration
options e.g.

    self.messaging_conf = self.useFixture(messaging.ConfFixture(cfg.CONF))
    self.messaging_conf.transport_driver = 'fake'

Change-Id: If0d837e1b86e3b04237fde522551cfb81505a543

7 files changed, 106 insertions, 22 deletions

diff --git a/doc/source/index.rst b/doc/source/index.rst
index 11ce1c3..fa951b7 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -17,6 +17,7 @@ Contents
    notifier
    serializer
    exceptions
+   conffixture
 
 Release Notes
 =============
diff --git a/oslo/messaging/__init__.py b/oslo/messaging/__init__.py
index 453a73e..73c6f2a 100644
--- a/oslo/messaging/__init__.py
+++ b/oslo/messaging/__init__.py
@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from .conffixture import *
 from .exceptions import *
 from .localcontext import *
 from .notify import *
diff --git a/oslo/messaging/conffixture.py b/oslo/messaging/conffixture.py
new file mode 100644
index 0000000..7dd06db
--- /dev/null
+++ b/oslo/messaging/conffixture.py
@@ -0,0 +1,87 @@
+
+# Copyright 2013 Red Hat, Inc.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+__all__ = ['ConfFixture']
+
+import sys
+
+import fixtures
+
+
+def _import_opts(conf, module, opts):
+    __import__(module)
+    conf.register_opts(getattr(sys.modules[module], opts))
+
+
+class ConfFixture(fixtures.Fixture):
+
+    """Tweak configuration options for unit testing.
+
+    oslo.messaging registers a number of configuration options, but rather than
+    directly referencing those options, users of the API should use this
+    interface for querying and overriding certain configuration options.
+
+    An example usage::
+
+        self.messaging_conf = self.useFixture(messaging.ConfFixture(cfg.CONF))
+        self.messaging_conf.transport_driver = 'fake'
+
+    :param conf: a ConfigOpts instance
+    :type conf: oslo.config.cfg.ConfigOpts
+    """
+
+    def __init__(self, conf):
+        self.conf = conf
+        _import_opts(self.conf,
+                     'oslo.messaging._drivers.impl_rabbit', 'rabbit_opts')
+        _import_opts(self.conf, 'oslo.messaging.rpc.client', '_client_opts')
+        _import_opts(self.conf, 'oslo.messaging.transport', '_transport_opts')
+
+    def setUp(self):
+        super(ConfFixture, self).setUp()
+        self.addCleanup(self.conf.reset)
+
+    @property
+    def transport_driver(self):
+        """The transport driver - e.g. 'rabbit', 'qpid' or 'fake'."""
+        return self.conf.rpc_backend
+
+    @transport_driver.setter
+    def transport_driver(self, value):
+        self.conf.set_override('rpc_backend', value)
+
+    @property
+    def in_memory(self):
+        """Use an in-memory transport; currently supported by rabbit driver."""
+        if (('rabbit' in self.transport_driver or
+             'kombu' in self.transport_driver)):
+            return self.conf.fake_rabbit
+        else:
+            return False
+
+    @in_memory.setter
+    def in_memory(self, value):
+        if (('rabbit' in self.transport_driver or
+             'kombu' in self.transport_driver)):
+            self.conf.set_override('fake_rabbit', value)
+
+    @property
+    def response_timeout(self):
+        """Default number of seconds to wait for a response from a call."""
+        return self.conf.rpc_response_timeout
+
+    @response_timeout.setter
+    def response_timeout(self, value):
+        self.conf.set_override('rpc_response_timeout', value)
diff --git a/requirements.txt b/requirements.txt
index 38a138e..84667de 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,9 @@
 oslo.config
 stevedore
 
+# for oslo.messging.conffixture
+fixtures>=0.3.12
+
 # for timeutils
 iso8601
 
diff --git a/test-requirements.txt b/test-requirements.txt
index 7181493..1503dde 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -5,7 +5,6 @@ flake8==2.0
 hacking>=0.5.6,<0.7
 
 discover
-fixtures>=0.3.12
 mox>=0.5.3
 python-subunit
 testrepository>=0.0.13
diff --git a/tests/test_rabbit.py b/tests/test_rabbit.py
index 4b6b28d..5cff175 100644
--- a/tests/test_rabbit.py
+++ b/tests/test_rabbit.py
@@ -27,7 +27,6 @@ from oslo import messaging
 from oslo.messaging._drivers import common as driver_common
 from oslo.messaging._drivers import impl_rabbit as rabbit_driver
 from oslo.messaging.openstack.common import jsonutils
-from oslo.messaging import transport as msg_transport
 from tests import utils as test_utils
 
 load_tests = testscenarios.load_tests_apply_scenarios
@@ -37,10 +36,8 @@ class TestRabbitDriverLoad(test_utils.BaseTestCase):
 
     def setUp(self):
         super(TestRabbitDriverLoad, self).setUp()
-        self.conf.register_opts(msg_transport._transport_opts)
-        self.conf.register_opts(rabbit_driver.rabbit_opts)
-        self.config(rpc_backend='rabbit')
-        self.config(fake_rabbit=True)
+        self.messaging_conf.transport_driver = 'rabbit'
+        self.messaging_conf.in_memory = True
 
     def test_driver_load(self):
         transport = messaging.get_transport(self.conf)
@@ -81,10 +78,8 @@ class TestRabbitTransportURL(test_utils.BaseTestCase):
 
     def setUp(self):
         super(TestRabbitTransportURL, self).setUp()
-        self.conf.register_opts(msg_transport._transport_opts)
-        self.conf.register_opts(rabbit_driver.rabbit_opts)
-        self.config(rpc_backend='rabbit')
-        self.config(fake_rabbit=True)
+        self.messaging_conf.transport_driver = 'rabbit'
+        self.messaging_conf.in_memory = True
 
     def test_transport_url(self):
         cnx_init = rabbit_driver.Connection.__init__
@@ -139,10 +134,8 @@ class TestSendReceive(test_utils.BaseTestCase):
 
     def setUp(self):
         super(TestSendReceive, self).setUp()
-        self.conf.register_opts(msg_transport._transport_opts)
-        self.conf.register_opts(rabbit_driver.rabbit_opts)
-        self.config(rpc_backend='rabbit')
-        self.config(fake_rabbit=True)
+        self.messaging_conf.transport_driver = 'rabbit'
+        self.messaging_conf.in_memory = True
 
     def test_send_receive(self):
         transport = messaging.get_transport(self.conf)
@@ -313,10 +306,8 @@ class TestRequestWireFormat(test_utils.BaseTestCase):
 
     def setUp(self):
         super(TestRequestWireFormat, self).setUp()
-        self.conf.register_opts(msg_transport._transport_opts)
-        self.conf.register_opts(rabbit_driver.rabbit_opts)
-        self.config(rpc_backend='rabbit')
-        self.config(fake_rabbit=True)
+        self.messaging_conf.transport_driver = 'rabbit'
+        self.messaging_conf.in_memory = True
 
         self.uuids = []
         self.orig_uuid4 = uuid.uuid4
@@ -462,10 +453,8 @@ class TestReplyWireFormat(test_utils.BaseTestCase):
 
     def setUp(self):
         super(TestReplyWireFormat, self).setUp()
-        self.conf.register_opts(msg_transport._transport_opts)
-        self.conf.register_opts(rabbit_driver.rabbit_opts)
-        self.config(rpc_backend='rabbit')
-        self.config(fake_rabbit=True)
+        self.messaging_conf.transport_driver = 'rabbit'
+        self.messaging_conf.in_memory = True
 
     def test_reply_wire_format(self):
         if hasattr(self, 'skip_msg'):
diff --git a/tests/utils.py b/tests/utils.py
index b683f6b..ae77197 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -58,6 +58,10 @@ class BaseTestCase(testtools.TestCase):
         self.conf = conf
         self.addCleanup(self.conf.reset)
 
+        from oslo.messaging import conffixture
+        self.messaging_conf = self.useFixture(
+            conffixture.ConfFixture(self.conf))
+
         moxfixture = self.useFixture(moxstubout.MoxStubout())
         self.mox = moxfixture.mox
         self.stubs = moxfixture.stubs