fix(storage/mongo): unclaimed messages not listed

Adds a unit test that reproduces this error and applies the fix.

The fix is subtle. When messages are unclaimed, their claim expiration
time and claim ID are set to 0 and None respectively. The cause for
the bug is that claim expiration time is set to 0, rather than a valid
datetime object. As a result, the comparison silently fails.

The fix: fast-forward the expiration time of a claim to now.

Change-Id: I7781795c394b2a471012e072a522ee228d56a894
Closes-Bug: #1210633

marconi/storage/mongodb/messages.py

@@ -373,8 +373,11 @@ class MessageController(storage.MessageBase):
         except ValueError:
             return
 
+        # NOTE(cpp-cabrera):  unclaim by setting the claim ID to None
+        # and the claim expiration time to now
+        now = timeutils.utcnow()
         self._col.update({'q': queue_name, 'p': project, 'c.id': cid},
-                         {'$set': {'c': {'id': None, 'e': 0}}},
+                         {'$set': {'c': {'id': None, 'e': now}}},
                          upsert=False, multi=True)
 
     def remove_expired(self):

marconi/tests/transport/wsgi/test_messages.py

@@ -311,6 +311,27 @@ class MessagesBaseTest(base.TestBase):
         self.simulate_get(path, '7e7e7e')
         self.assertEquals(self.srmock.status, falcon.HTTP_400)
 
+    # NOTE(cpp-cabrera): regression test against bug #1210633
+    def test_when_claim_deleted_then_messages_unclaimed(self):
+        path = self.queue_path
+        self._post_messages(path + '/messages', repeat=5)
+
+        # post claim
+        self.simulate_post(path + '/claims', self.project_id,
+                           body='{"ttl": 100, "grace": 100}')
+        self.assertEquals(self.srmock.status, falcon.HTTP_201)
+        location = self.srmock.headers_dict['Location']
+
+        # release claim
+        self.simulate_delete(location, self.project_id)
+        self.assertEquals(self.srmock.status, falcon.HTTP_204)
+
+        # get unclaimed messages
+        self.simulate_get(path + '/messages', self.project_id,
+                          query_string='echo=true',
+                          headers=self.headers)
+        self.assertEquals(self.srmock.status, falcon.HTTP_200)
+
     def _post_messages(self, target, repeat=1):
         doc = json.dumps([{'body': 239, 'ttl': 300}] * repeat)
         self.simulate_post(target, self.project_id, body=doc,