De-emphasize 'project' and 'connection' as args to 'list_topics'.

Addresses: #742 (comment).

gcloud/pubsub/api.py

@@ -15,10 +15,18 @@
 """ Define API functions (not bound to classes)."""
 
 
-def list_topics(project=None, connection=None,
-                page_size=None, page_token=None):
+def list_topics(page_size=None, page_token=None,
+                project=None, connection=None):
     """List topics for a given project.
 
+    :type page_size: int
+    :param page_size: maximum number of topics to return, If not passed,
+                      defaults to a value set by the API.
+
+    :type page_token: string
+    :param page_token: opaque marker for the next "page" of topics. If not
+                       passed, the API will return the first page of topics.
+
     :type project: string
     :param project: project ID to query.  If not passed, defaults to the
                     project ID inferred from the environment.
@@ -28,14 +36,6 @@ def list_topics(project=None, connection=None,
                        defaults to the connection inferred from the
                        environment.
 
-    :type page_size: int
-    :param page_size: maximum number of topics to return, If not passed,
-                      defaults to a value set by the API.
-
-    :type page_token: string
-    :param page_token: opaque marker for the next "page" of topics. If not
-                       passed, the API will return the first page of topics.
-
     :rtype: dict
     :returns: keys include ``topics`` (a list of topic mappings) and
               ``nextPageToken`` (a string:  if non-empty, indicates that

gcloud/pubsub/test_api.py

@@ -28,7 +28,7 @@ def test_w_explicit_connection_no_paging(self):
         returned = {'topics': [{'name': TOPIC_NAME}],
                     'nextPageToken': TOKEN}
         conn = _Connection(returned)
-        response = self._callFUT(PROJECT, conn)
+        response = self._callFUT(project=PROJECT, connection=conn)
         topics = response['topics']
         self.assertEqual(len(topics), 1)
         self.assertEqual(topics[0], {'name': TOPIC_NAME})
@@ -48,7 +48,7 @@ def test_w_explicit_connection_w_paging(self):
         returned = {'topics': [{'name': TOPIC_NAME}],
                     'nextPageToken': TOKEN2}
         conn = _Connection(returned)
-        response = self._callFUT(PROJECT, conn, SIZE, TOKEN1)
+        response = self._callFUT(SIZE, TOKEN1, PROJECT, conn)
         topics = response['topics']
         self.assertEqual(len(topics), 1)
         self.assertEqual(topics[0], {'name': TOPIC_NAME})