Bugbear: Add Mutable Parameter fixes

changelog.d/9682.misc

@@ -0,0 +1 @@
+Introduce flake8-bugbear to the test suite and fix some of its lint violations.

contrib/cmdclient/console.py

@@ -24,6 +24,7 @@
 import time
 import urllib
 from http import TwistedHttpClient
+from typing import Optional
 
 import nacl.encoding
 import nacl.signing
@@ -718,7 +719,7 @@ def _run_and_pprint(
         method,
         path,
         data=None,
-        query_params={"access_token": None},
+        query_params: Optional[dict] = None,
         alt_text=None,
     ):
         """Runs an HTTP request and pretty prints the output.
@@ -729,6 +730,8 @@ def _run_and_pprint(
             data: Raw JSON data if any
             query_params: dict of query parameters to add to the url
         """
+        query_params = query_params or {"access_token": None}
+
         url = self._url() + path
         if "access_token" in query_params:
             query_params["access_token"] = self._tok()

contrib/cmdclient/http.py

@@ -16,6 +16,7 @@
 import json
 import urllib
 from pprint import pformat
+from typing import Optional
 
 from twisted.internet import defer, reactor
 from twisted.web.client import Agent, readBody
@@ -85,8 +86,9 @@ def get_json(self, url, args=None):
         body = yield readBody(response)
         defer.returnValue(json.loads(body))
 
-    def _create_put_request(self, url, json_data, headers_dict={}):
+    def _create_put_request(self, url, json_data, headers_dict: Optional[dict] = None):
         """Wrapper of _create_request to issue a PUT request"""
+        headers_dict = headers_dict or {}
 
         if "Content-Type" not in headers_dict:
             raise defer.error(RuntimeError("Must include Content-Type header for PUTs"))
@@ -95,14 +97,16 @@ def _create_put_request(self, url, json_data, headers_dict={}):
             "PUT", url, producer=_JsonProducer(json_data), headers_dict=headers_dict
         )
 
-    def _create_get_request(self, url, headers_dict={}):
+    def _create_get_request(self, url, headers_dict: Optional[dict] = None):
         """Wrapper of _create_request to issue a GET request"""
-        return self._create_request("GET", url, headers_dict=headers_dict)
+        return self._create_request("GET", url, headers_dict=headers_dict or {})
 
     @defer.inlineCallbacks
     def do_request(
-        self, method, url, data=None, qparams=None, jsonreq=True, headers={}
+        self, method, url, data=None, qparams=None, jsonreq=True, headers: dict = None
     ):
+        headers = headers or {}
+
         if qparams:
             url = "%s?%s" % (url, urllib.urlencode(qparams, True))
 
@@ -123,8 +127,12 @@ def do_request(
         defer.returnValue(json.loads(body))
 
     @defer.inlineCallbacks
-    def _create_request(self, method, url, producer=None, headers_dict={}):
+    def _create_request(
+        self, method, url, producer=None, headers_dict: Optional[dict] = None
+    ):
         """Creates and sends a request to the given url"""
+        headers_dict = headers_dict or {}
+
         headers_dict["User-Agent"] = ["Synapse Cmd Client"]
 
         retries_left = 5

setup.cfg

@@ -18,8 +18,8 @@ ignore =
 #  E203: whitespace before ':' (which is contrary to pep8?)
 #  E731: do not assign a lambda expression, use a def
 #  E501: Line too long (black enforces this for us)
-#  B00*: Subsection of the bugbear suite (TODO: add in remaining fixes)
-ignore=W503,W504,E203,E731,E501,B006,B007,B008
+#  B007: Subsection of the bugbear suite (TODO: add in remaining fixes)
+ignore=W503,W504,E203,E731,E501,B007
 
 [isort]
 line_length = 88

synapse/appservice/scheduler.py

@@ -49,7 +49,7 @@
 components.
 """
 import logging
-from typing import List
+from typing import List, Optional
 
 from synapse.appservice import ApplicationService, ApplicationServiceState
 from synapse.events import EventBase
@@ -191,11 +191,11 @@ async def send(
         self,
         service: ApplicationService,
         events: List[EventBase],
-        ephemeral: List[JsonDict] = [],
+        ephemeral: Optional[List[JsonDict]] = None,
     ):
         try:
             txn = await self.store.create_appservice_txn(
-                service=service, events=events, ephemeral=ephemeral
+                service=service, events=events, ephemeral=ephemeral or []
             )
             service_is_up = await self._is_service_up(service)
             if service_is_up:

synapse/config/ratelimiting.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Dict
+from typing import Dict, Optional
 
 from ._base import Config
 
@@ -21,8 +21,10 @@ class RateLimitConfig:
     def __init__(
         self,
         config: Dict[str, float],
-        defaults={"per_second": 0.17, "burst_count": 3.0},
+        defaults: Optional[Dict[str, float]] = None,
     ):
+        defaults = defaults or {"per_second": 0.17, "burst_count": 3.0}
+
         self.per_second = config.get("per_second", defaults["per_second"])
         self.burst_count = int(config.get("burst_count", defaults["burst_count"]))
 

synapse/events/__init__.py

@@ -330,9 +330,11 @@ def __init__(
         self,
         event_dict: JsonDict,
         room_version: RoomVersion,
-        internal_metadata_dict: JsonDict = {},
+        internal_metadata_dict: Optional[JsonDict] = None,
         rejected_reason: Optional[str] = None,
     ):
+        internal_metadata_dict = internal_metadata_dict or {}
+
         event_dict = dict(event_dict)
 
         # Signatures is a dict of dicts, and this is faster than doing a
@@ -386,9 +388,11 @@ def __init__(
         self,
         event_dict: JsonDict,
         room_version: RoomVersion,
-        internal_metadata_dict: JsonDict = {},
+        internal_metadata_dict: Optional[JsonDict] = None,
         rejected_reason: Optional[str] = None,
     ):
+        internal_metadata_dict = internal_metadata_dict or {}
+
         event_dict = dict(event_dict)
 
         # Signatures is a dict of dicts, and this is faster than doing a
@@ -507,9 +511,11 @@ def _event_type_from_format_version(format_version: int) -> Type[EventBase]:
 def make_event_from_dict(
     event_dict: JsonDict,
     room_version: RoomVersion = RoomVersions.V1,
-    internal_metadata_dict: JsonDict = {},
+    internal_metadata_dict: Optional[JsonDict] = None,
     rejected_reason: Optional[str] = None,
 ) -> EventBase:
     """Construct an EventBase from the given event dict"""
     event_type = _event_type_from_format_version(room_version.event_format)
-    return event_type(event_dict, room_version, internal_metadata_dict, rejected_reason)
+    return event_type(
+        event_dict, room_version, internal_metadata_dict or {}, rejected_reason
+    )

synapse/federation/units.py

@@ -18,6 +18,7 @@
 """
 
 import logging
+from typing import Optional
 
 import attr
 
@@ -98,7 +99,7 @@ class Transaction(JsonEncodedObject):
         "pdus",
     ]
 
-    def __init__(self, transaction_id=None, pdus=[], **kwargs):
+    def __init__(self, transaction_id=None, pdus: Optional[list] = None, **kwargs):
         """If we include a list of pdus then we decode then as PDU's
         automatically.
         """
@@ -107,7 +108,7 @@ def __init__(self, transaction_id=None, pdus=[], **kwargs):
         if "edus" in kwargs and not kwargs["edus"]:
             del kwargs["edus"]
 
-        super().__init__(transaction_id=transaction_id, pdus=pdus, **kwargs)
+        super().__init__(transaction_id=transaction_id, pdus=pdus or [], **kwargs)
 
     @staticmethod
     def create_new(pdus, **kwargs):

synapse/handlers/appservice.py

@@ -182,7 +182,7 @@ def notify_interested_services_ephemeral(
         self,
         stream_key: str,
         new_token: Optional[int],
-        users: Collection[Union[str, UserID]] = [],
+        users: Optional[Collection[Union[str, UserID]]] = None,
     ):
         """This is called by the notifier in the background
         when a ephemeral event handled by the homeserver.
@@ -215,7 +215,7 @@ def notify_interested_services_ephemeral(
         # We only start a new background process if necessary rather than
         # optimistically (to cut down on overhead).
         self._notify_interested_services_ephemeral(
-            services, stream_key, new_token, users
+            services, stream_key, new_token, users or []
         )
 
     @wrap_as_background_process("notify_interested_services_ephemeral")

synapse/handlers/federation.py

@@ -1772,7 +1772,7 @@ async def _make_and_verify_event(
         room_id: str,
         user_id: str,
         membership: str,
-        content: JsonDict = {},
+        content: JsonDict,
         params: Optional[Dict[str, Union[str, Iterable[str]]]] = None,
     ) -> Tuple[str, EventBase, RoomVersion]:
         (

synapse/handlers/message.py

@@ -137,7 +137,7 @@ async def get_state_events(
         self,
         user_id: str,
         room_id: str,
-        state_filter: StateFilter = StateFilter.all(),
+        state_filter: Optional[StateFilter] = None,
         at_token: Optional[StreamToken] = None,
         is_guest: bool = False,
     ) -> List[dict]:
@@ -164,6 +164,8 @@ async def get_state_events(
             AuthError (403) if the user doesn't have permission to view
             members of this room.
         """
+        state_filter = state_filter or StateFilter.all()
+
         if at_token:
             # FIXME this claims to get the state at a stream position, but
             # get_recent_events_for_room operates by topo ordering. This therefore
@@ -874,7 +876,7 @@ async def handle_new_client_event(
         event: EventBase,
         context: EventContext,
         ratelimit: bool = True,
-        extra_users: List[UserID] = [],
+        extra_users: Optional[List[UserID]] = None,
         ignore_shadow_ban: bool = False,
     ) -> EventBase:
         """Processes a new event.
@@ -902,6 +904,7 @@ async def handle_new_client_event(
         Raises:
             ShadowBanError if the requester has been shadow-banned.
         """
+        extra_users = extra_users or []
 
         # we don't apply shadow-banning to membership events here. Invites are blocked
         # higher up the stack, and we allow shadow-banned users to send join and leave
@@ -1071,7 +1074,7 @@ async def persist_and_notify_client_event(
         event: EventBase,
         context: EventContext,
         ratelimit: bool = True,
-        extra_users: List[UserID] = [],
+        extra_users: Optional[List[UserID]] = None,
     ) -> EventBase:
         """Called when we have fully built the event, have already
         calculated the push actions for the event, and checked auth.
@@ -1083,6 +1086,8 @@ async def persist_and_notify_client_event(
             it was de-duplicated (e.g. because we had already persisted an
             event with the same transaction ID.)
         """
+        extra_users = extra_users or []
+
         assert self.storage.persistence is not None
         assert self._events_shard_config.should_handle(
             self._instance_name, event.room_id

synapse/handlers/register.py

@@ -169,7 +169,7 @@ async def register_user(
         user_type: Optional[str] = None,
         default_display_name: Optional[str] = None,
         address: Optional[str] = None,
-        bind_emails: Iterable[str] = [],
+        bind_emails: Optional[Iterable[str]] = None,
         by_admin: bool = False,
         user_agent_ips: Optional[List[Tuple[str, str]]] = None,
         auth_provider_id: Optional[str] = None,
@@ -204,6 +204,8 @@ async def register_user(
         Raises:
             SynapseError if there was a problem registering.
         """
+        bind_emails = bind_emails or []
+
         await self.check_registration_ratelimit(address)
 
         result = await self.spam_checker.check_registration_for_spam(

synapse/handlers/sync.py

@@ -548,7 +548,7 @@ async def _load_filtered_recents(
         )
 
     async def get_state_after_event(
-        self, event: EventBase, state_filter: StateFilter = StateFilter.all()
+        self, event: EventBase, state_filter: Optional[StateFilter] = None
     ) -> StateMap[str]:
         """
         Get the room state after the given event
@@ -558,7 +558,7 @@ async def get_state_after_event(
             state_filter: The state filter used to fetch state from the database.
         """
         state_ids = await self.state_store.get_state_ids_for_event(
-            event.event_id, state_filter=state_filter
+            event.event_id, state_filter=state_filter or StateFilter.all()
         )
         if event.is_state():
             state_ids = dict(state_ids)
@@ -569,7 +569,7 @@ async def get_state_at(
         self,
         room_id: str,
         stream_position: StreamToken,
-        state_filter: StateFilter = StateFilter.all(),
+        state_filter: Optional[StateFilter] = None,
     ) -> StateMap[str]:
         """Get the room state at a particular stream position
 
@@ -589,7 +589,7 @@ async def get_state_at(
         if last_events:
             last_event = last_events[-1]
             state = await self.get_state_after_event(
-                last_event, state_filter=state_filter
+                last_event, state_filter=state_filter or StateFilter.all()
             )
 
         else:

synapse/http/client.py

@@ -297,7 +297,7 @@ class SimpleHttpClient:
     def __init__(
         self,
         hs: "HomeServer",
-        treq_args: Dict[str, Any] = {},
+        treq_args: Optional[Dict[str, Any]] = None,
         ip_whitelist: Optional[IPSet] = None,
         ip_blacklist: Optional[IPSet] = None,
         use_proxy: bool = False,
@@ -317,7 +317,7 @@ def __init__(
 
         self._ip_whitelist = ip_whitelist
         self._ip_blacklist = ip_blacklist
-        self._extra_treq_args = treq_args
+        self._extra_treq_args = treq_args or {}
 
         self.user_agent = hs.version_string
         self.clock = hs.get_clock()

synapse/http/proxyagent.py

@@ -27,7 +27,7 @@
 from twisted.web.client import URI, BrowserLikePolicyForHTTPS, _AgentBase
 from twisted.web.error import SchemeNotSupported
 from twisted.web.http_headers import Headers
-from twisted.web.iweb import IAgent
+from twisted.web.iweb import IAgent, IPolicyForHTTPS
 
 from synapse.http.connectproxyclient import HTTPConnectProxyEndpoint
 
@@ -88,12 +88,14 @@ def __init__(
         self,
         reactor,
         proxy_reactor=None,
-        contextFactory=BrowserLikePolicyForHTTPS(),
+        contextFactory: Optional[IPolicyForHTTPS] = None,
         connectTimeout=None,
         bindAddress=None,
         pool=None,
         use_proxy=False,
     ):
+        contextFactory = contextFactory or BrowserLikePolicyForHTTPS()
+
         _AgentBase.__init__(self, reactor, pool)
 
         if proxy_reactor is None:

synapse/logging/opentracing.py

@@ -486,7 +486,7 @@ def start_active_span_from_request(
 def start_active_span_from_edu(
     edu_content,
     operation_name,
-    references=[],
+    references: Optional[list] = None,
     tags=None,
     start_time=None,
     ignore_active_span=False,
@@ -501,6 +501,7 @@ def start_active_span_from_edu(
 
         For the other args see opentracing.tracer
     """
+    references = references or []
 
     if opentracing is None:
         return noop_context_manager()