Add typing to SyncHandler (#6821)

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

changelog.d/6821.misc

@@ -0,0 +1 @@
+Add type hints to `SyncHandler`.

synapse/events/__init__.py

@@ -189,8 +189,14 @@ class EventBase(object):
     redacts = _event_dict_property("redacts", None)
     room_id = _event_dict_property("room_id")
     sender = _event_dict_property("sender")
+    state_key = _event_dict_property("state_key")
+    type = _event_dict_property("type")
     user_id = _event_dict_property("sender")
 
+    @property
+    def event_id(self) -> str:
+        raise NotImplementedError()
+
     @property
     def membership(self):
         return self.content["membership"]
@@ -281,10 +287,7 @@ class FrozenEvent(EventBase):
         else:
             frozen_dict = event_dict
 
-        self.event_id = event_dict["event_id"]
+        self._event_id = event_dict["event_id"]
-        self.type = event_dict["type"]
-        if "state_key" in event_dict:
-            self.state_key = event_dict["state_key"]
 
         super(FrozenEvent, self).__init__(
             frozen_dict,
@@ -294,6 +297,10 @@ class FrozenEvent(EventBase):
             rejected_reason=rejected_reason,
         )
 
+    @property
+    def event_id(self) -> str:
+        return self._event_id
+
     def __str__(self):
         return self.__repr__()
 
@@ -332,9 +339,6 @@ class FrozenEventV2(EventBase):
             frozen_dict = event_dict
 
         self._event_id = None
-        self.type = event_dict["type"]
-        if "state_key" in event_dict:
-            self.state_key = event_dict["state_key"]
 
         super(FrozenEventV2, self).__init__(
             frozen_dict,

tests/storage/test_redaction.py

@@ -238,8 +238,11 @@ class RedactionTestCase(unittest.HomeserverTestCase):
             @defer.inlineCallbacks
             def build(self, prev_event_ids):
                 built_event = yield self._base_builder.build(prev_event_ids)
-                built_event.event_id = self._event_id
+
+                built_event._event_id = self._event_id
                 built_event._event_dict["event_id"] = self._event_id
+                assert built_event.event_id == self._event_id
+
                 return built_event
 
             @property

tox.ini

@@ -180,6 +180,7 @@ commands = mypy \
             synapse/api \
             synapse/config/ \
             synapse/federation/transport \
+            synapse/handlers/sync.py \
             synapse/handlers/ui_auth \
             synapse/logging/ \
             synapse/module_api \