Address nits from service create/destroy notification review

This adds two things from the review of change
I955d98f9fd4b121f98e172e5ab30eb668a24006d:

1. A utility method to convert a service binary to a valid
   notification source.

2. Adds a comment in the functional test reminding us that
   we're using the latest microversion which is how we get
   the service uuid from the REST API.

Change-Id: If67b4e07d608f323c1154f7f379d4eb849e46fbf

nova/notifications/objects/base.py

@@ -162,11 +162,7 @@ class NotificationPublisher(NotificationObject):
 
     @classmethod
     def from_service_obj(cls, service):
-        # nova-osapi_compute binary name needs to be translated to nova-api
-        # notification source enum value.
-        source = ("nova-api"
-                  if service.binary == "nova-osapi_compute"
-                  else service.binary)
+        source = fields.NotificationSource.get_source_by_binary(service.binary)
         return cls(host=service.host, source=source)
 
 

nova/objects/fields.py

@@ -809,6 +809,12 @@ class NotificationSource(BaseNovaEnum):
     ALL = (API, COMPUTE, CONDUCTOR, SCHEDULER,
            NETWORK, CONSOLEAUTH, CELLS, CONSOLE, METADATA)
 
+    @staticmethod
+    def get_source_by_binary(binary):
+        # nova-osapi_compute binary name needs to be translated to nova-api
+        # notification source enum value.
+        return "nova-api" if binary == "nova-osapi_compute" else binary
+
 
 class NotificationAction(BaseNovaEnum):
     UPDATE = 'update'

nova/tests/functional/notification_sample_tests/test_service.py

@@ -151,6 +151,8 @@ class TestServiceNotificationSample(TestServiceNotificationBase):
 
     def test_service_destroy(self):
         self.compute2 = self.start_service('compute', host='host2')
+        # This test runs with the latest microversion by default so we get the
+        # service uuid back from the REST API.
         compute2_service_id = self.admin_api.get_services(
             host=self.compute2.host, binary='nova-compute')[0]['id']
         self.admin_api.api_delete('os-services/%s' % compute2_service_id)

nova/tests/unit/objects/test_fields.py

@@ -736,3 +736,13 @@ class TestSchemaGeneration(test.NoDBTestCase):
         expected = {'type': ['string'], 'pattern': '[a-z]+[0-9]+',
                     'readonly': False}
         self.assertEqual(expected, field.get_schema())
+
+
+class TestNotificationSource(test.NoDBTestCase):
+    def test_get_source_by_binary(self):
+        self.assertEqual('nova-api',
+                         fields.NotificationSource.get_source_by_binary(
+                             'nova-osapi_compute'))
+        self.assertEqual('nova-metadata',
+                         fields.NotificationSource.get_source_by_binary(
+                             'nova-metadata'))