PYTHON-2116 Sort servers by address in topology repr

Author: ShaneHarvey

pymongo/topology_description.py

@@ -289,9 +289,12 @@ def has_writable_server(self):
         return self.has_readable_server(ReadPreference.PRIMARY)
 
     def __repr__(self):
+        # Sort the servers by address.
+        servers = sorted(self._server_descriptions.values(),
+                         key=lambda sd: sd.address)
         return "<%s id: %s, topology_type: %s, servers: %r>" % (
             self.__class__.__name__, self._topology_settings._topology_id,
-            self.topology_type_name, list(self._server_descriptions.values()))
+            self.topology_type_name, servers)
 
 
 # If topology type is Unknown and we receive an ismaster response, what should

test/test_topology.py

@@ -624,13 +624,15 @@ def test_topology_repr(self):
             'ok': 1,
             'ismaster': True,
             'setName': 'rs',
-            'hosts': ['a', 'b']})
+            'hosts': ['a', 'c', 'b']})
         self.assertEqual(
             repr(t.description),
             "<TopologyDescription id: %s, "
             "topology_type: ReplicaSetWithPrimary, servers: ["
             "<ServerDescription ('a', 27017) server_type: RSPrimary, rtt: 0>, "
             "<ServerDescription ('b', 27017) server_type: Unknown,"
+            " rtt: None>, "
+            "<ServerDescription ('c', 27017) server_type: Unknown,"
             " rtt: None>]>" % (t._topology_id,))