Enable fatal exceptions during tests

This allows tests to catch string format errors in exception
messages.

Change-Id: I66d0363c02ef99482d4bec27b90584f8cea80e7a

neutron_lib/tests/_base.py

@@ -29,6 +29,7 @@ import testtools
 
 from neutron_lib._i18n import _
 from neutron_lib import constants
+from neutron_lib import exceptions
 
 from neutron_lib.tests import _post_mortem_debug as post_mortem_debug
 from neutron_lib.tests import _tools as tools
@@ -117,6 +118,11 @@ class BaseTestCase(testtools.TestCase):
     def setUp(self):
         super(BaseTestCase, self).setUp()
 
+        # Enabling 'use_fatal_exceptions' allows us to catch string
+        # substitution format errors in exception messages.
+        mock.patch.object(exceptions.NeutronException, 'use_fatal_exceptions',
+                          return_value=True).start()
+
         # Update the default QueuePool parameters. These can be tweaked by the
         # conf variables - max_pool_size, max_overflow and pool_timeout
         db_options.set_defaults(

neutron_lib/tests/unit/test_exceptions.py

@@ -36,7 +36,6 @@ class TestExceptions(base.BaseTestCase):
         raise_exc_class = functools.partial(_raise, exc_class)
         e = self.assertRaises(exc_class, raise_exc_class, **kwargs)
         self.assertEqual(expected_msg, str(e))
-        self.assertFalse(e.use_fatal_exceptions())
 
     def test_base(self):
         self._check_nexc(
@@ -64,7 +63,7 @@ class TestExceptions(base.BaseTestCase):
             self._check_nexc(
                 ne.BadRequest,
                 _('Bad A request: B.'),
-                bad_resource='A', bad_msg='B')
+                resource='A', msg='B')
         except AttributeError:
             pass