Be explicit about which conf is being used by policy enforcer

We've got a tradition of avoiding global config where possible, so
extract a _get_enforcer private method which allows us to do some
testing without relying on the implicit global config.

Change-Id: Icb2198ebedb2ff29347ebafda46690a908bf9d27

placement/policy.py

@@ -52,7 +52,11 @@ def get_enforcer():
     # files from overrides on disk and defaults in code. We can just pass an
     # empty list and let oslo do the config lifting for us.
     cfg.CONF([], project='placement')
-    init(cfg.CONF)
+    return _get_enforcer(cfg.CONF)
+
+
+def _get_enforcer(conf):
+    init(conf)
     return _ENFORCER
 
 

placement/tests/unit/test_policy.py

@@ -59,7 +59,7 @@ class PlacementPolicyTestCase(testtools.TestCase):
                           policy.authorize, self.ctxt, action, self.target)
 
         # Load the default action and rule (defaults to "any").
-        enforcer = policy.get_enforcer()
+        enforcer = policy._get_enforcer(self.conf_fixture.conf)
         rule = oslo_policy.RuleDefault(action, '')
         enforcer.register_default(rule)