testing: Reset affinity support global variables

Ran into this randomly today, if a test sets
CONF.scheduler.enabled_filters to a non-default value, the affinity
support global variables will be set to False which can affect
subsequent test runs that expect the default configuration (affinity
filter support enabled).

Example error:

  WARNING [nova.scheduler.utils] Failed to
    compute_task_build_instances: ServerGroup policy is not supported:
      ServerGroupAffinityFilter not configured

This resets the global variables during base test setup, similar to how
other globals are reset.

Change-Id: Icbc75b1001c0a609280241f99a780313b244aa9d

Author: melwitt

nova/scheduler/utils.py

@@ -1080,6 +1080,17 @@ def validate_weigher(weigher):
 _SUPPORTS_SOFT_ANTI_AFFINITY = None
 
 
+def reset_globals():
+    global _SUPPORTS_AFFINITY
+    _SUPPORTS_AFFINITY = None
+    global _SUPPORTS_ANTI_AFFINITY
+    _SUPPORTS_ANTI_AFFINITY = None
+    global _SUPPORTS_SOFT_AFFINITY
+    _SUPPORTS_SOFT_AFFINITY = None
+    global _SUPPORTS_SOFT_ANTI_AFFINITY
+    _SUPPORTS_SOFT_ANTI_AFFINITY = None
+
+
 def _get_group_details(context, instance_uuid, user_group_hosts=None):
     """Provide group_hosts and group_policies sets related to instances if
     those instances are belonging to a group and if corresponding filters are

nova/test.py

@@ -62,6 +62,7 @@
 from nova.objects import base as objects_base
 from nova import quota
 from nova.scheduler.client import report
+from nova.scheduler import utils as scheduler_utils
 from nova.tests import fixtures as nova_fixtures
 from nova.tests.unit import matchers
 from nova import utils
@@ -310,6 +311,12 @@ def setUp(self):
         if self.STUB_COMPUTE_ID:
             self.useFixture(nova_fixtures.ComputeNodeIdFixture())
 
+        # Reset globals indicating affinity filter support. Some tests may set
+        # self.flags(enabled_filters=...) which could make the affinity filter
+        # support globals get set to a non-default configuration which affects
+        # all other tests.
+        scheduler_utils.reset_globals()
+
     def _setup_cells(self):
         """Setup a normal cellsv2 environment.