Type hints and validation improvements. (#9321)

* Adds type hints to the groups servlet and stringutils code.
* Assert the maximum length of some input values for spec compliance.

1 files changed, 14 insertions, 2 deletions

diff --git a/synapse/server.py b/synapse/server.py
index 9bdd3177d7..6b3892e3cd 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -25,7 +25,17 @@ import abc
 import functools
 import logging
 import os
-from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, TypeVar, cast
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Dict,
+    List,
+    Optional,
+    TypeVar,
+    Union,
+    cast,
+)
 
 import twisted.internet.base
 import twisted.internet.tcp
@@ -588,7 +598,9 @@ class HomeServer(metaclass=abc.ABCMeta):
         return UserDirectoryHandler(self)
 
     @cache_in_self
-    def get_groups_local_handler(self):
+    def get_groups_local_handler(
+        self,
+    ) -> Union[GroupsLocalWorkerHandler, GroupsLocalHandler]:
         if self.config.worker_app:
             return GroupsLocalWorkerHandler(self)
         else: