fix WarningsFixture for public consumption

The neutron.tests.tools was recently made public and along with it the
WarningsFixture. However the WarningsFixture as-is doesn't support
filtering warnings from other modules. This patch address that by
accepting an constructor arg to add other module regular expressions to
filter. It also moves WarningsFixture to the fixture module where it
seems to make the most sense.

For a sample consumption patch see:
https://review.openstack.org/#/c/651370/

Change-Id: I08c713916aef407ba108ed2c67c3e99892f5883a

neutron_lib/fixture.py

@@ -11,6 +11,7 @@
 # under the License.
 
 import copy
+import warnings
 
 import fixtures
 import mock
@@ -308,3 +309,27 @@ class OpenFixture(fixtures.Fixture):
                                  new=replacement_open)
         self._patch.start()
         self.addCleanup(self._patch.stop)
+
+
+class WarningsFixture(fixtures.Fixture):
+    """Filters out warnings during test runs."""
+
+    warning_types = (
+        DeprecationWarning, PendingDeprecationWarning, ImportWarning
+    )
+
+    def __init__(self, module_re=None):
+        """Create a new WarningsFixture.
+
+        :param module_re: A list of regular expression strings that will be
+            used with filterwarnings. Multiple expressions are or'd together.
+        """
+        self._modules = ['^neutron_lib\\.']
+        if module_re:
+            self._modules.extend(module_re)
+
+    def _setUp(self):
+        self.addCleanup(warnings.resetwarnings)
+        for wtype in self.warning_types:
+            warnings.filterwarnings(
+                "always", category=wtype, module='|'.join(self._modules))

neutron_lib/tests/_base.py

@@ -32,7 +32,6 @@ from neutron_lib import exceptions
 from neutron_lib import fixture
 
 from neutron_lib.tests import _post_mortem_debug as post_mortem_debug
-from neutron_lib.tests import tools
 
 
 CONF = cfg.CONF
@@ -139,7 +138,7 @@ class BaseTestCase(testtools.TestCase):
                 debugger))
 
         # Make sure we see all relevant deprecation warnings when running tests
-        self.useFixture(tools.WarningsFixture())
+        self.useFixture(fixture.WarningsFixture())
 
         if bool_from_env('OS_DEBUG'):
             _level = std_logging.DEBUG

neutron_lib/tests/tools.py

@@ -17,9 +17,7 @@ import os
 import platform
 import random
 import time
-import warnings
 
-import fixtures
 import netaddr
 
 from neutron_lib.utils import helpers
@@ -39,20 +37,6 @@ class UnorderedList(list):
         return not self == other
 
 
-class WarningsFixture(fixtures.Fixture):
-    """Filters out warnings during test runs."""
-
-    warning_types = (
-        DeprecationWarning, PendingDeprecationWarning, ImportWarning
-    )
-
-    def _setUp(self):
-        self.addCleanup(warnings.resetwarnings)
-        for wtype in self.warning_types:
-            warnings.filterwarnings(
-                "always", category=wtype, module='^neutron_lib\\.')
-
-
 def is_bsd():
     """Return True on BSD-based systems."""
 

neutron_lib/tests/unit/test_fixture.py

@@ -10,8 +10,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import mock
+import re
 
+import mock
 from oslo_config import cfg
 from oslo_db import options
 from oslotest import base
@@ -178,3 +179,19 @@ class DBResourceExtendFixtureTestCase(base.BaseTestCase):
         db_fixture.cleanUp()
         self.assertEqual(
             orig_methods, resource_extend._resource_extend_functions)
+
+
+class WarningsFixture(base.BaseTestCase):
+
+    @mock.patch.object(fixture.warnings, 'filterwarnings')
+    def test_fixture_regex(self, mock_filterwarnings):
+        module_re = ['^neutron\\.']
+        warn_fixture = fixture.WarningsFixture(module_re=module_re)
+        warn_fixture.setUp()
+        call_re = mock_filterwarnings.mock_calls[0][2]['module']
+        self.assertEqual('^neutron_lib\\.|^neutron\\.', call_re)
+        self.assertIsNotNone(re.compile(call_re))
+        self.assertIsNotNone(re.search(call_re, 'neutron.db.blah'))
+        self.assertIsNotNone(re.search(call_re, 'neutron_lib.db.blah'))
+        self.assertIsNone(re.search(
+            call_re, 'neutron_dynamic_routing.db.blah'))

releasenotes/notes/fix-warnfixture-c9457c50d0d5c5a7.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  -  The ``WarningsFixture`` is now available in ``neutron_lib.fixture`` and
+     its constructor accepts additional module's to use with filterwarnings.