python: Replace None defaults with empty collections where appropriate.

Use read-only types (List ↦ Sequence, Dict ↦ Mapping, Set ↦
AbstractSet) to guard against accidental mutation of the default
value.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

confirmation/models.py

@@ -4,7 +4,7 @@ __revision__ = '$Id: models.py 28 2009-10-22 15:03:02Z jarek.zgoda $'
 import datetime
 import string
 from random import SystemRandom
-from typing import Dict, Optional, Union
+from typing import Mapping, Optional, Union
 
 from django.conf import settings
 from django.contrib.contenttypes.fields import GenericForeignKey
@@ -65,7 +65,7 @@ def get_object_from_key(confirmation_key: str,
 
 def create_confirmation_link(obj: ContentType, host: str,
                              confirmation_type: int,
-                             url_args: Optional[Dict[str, str]]=None) -> str:
+                             url_args: Mapping[str, str] = {}) -> str:
     key = generate_key()
     realm = None
     if hasattr(obj, 'realm'):
@@ -79,9 +79,8 @@ def create_confirmation_link(obj: ContentType, host: str,
 
 def confirmation_url(confirmation_key: str, host: str,
                      confirmation_type: int,
-                     url_args: Optional[Dict[str, str]]=None) -> str:
+                     url_args: Mapping[str, str] = {}) -> str:
-    if url_args is None:
+    url_args = dict(url_args)
-        url_args = {}
     url_args['confirmation_key'] = confirmation_key
     return '%s%s%s' % (settings.EXTERNAL_URI_SCHEME, host,
                        reverse(_properties[confirmation_type].url_name, kwargs=url_args))

puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_user_zephyr_mirror_liveness

@@ -24,7 +24,7 @@ sys.path.append('/home/zulip/deployments/current/zerver')
 
 django.setup()
 
-from typing import Any, Dict, Optional, Set
+from typing import AbstractSet, Any, Dict
 
 from zerver.models import UserActivity
 
@@ -35,7 +35,7 @@ states: Dict[str, int] = {
     "UNKNOWN": 3,
 }
 
-def report(state: str, short_msg: str, too_old: Optional[Set[Any]] = None) -> None:
+def report(state: str, short_msg: str, too_old: AbstractSet[Any] = set()) -> None:
     too_old_data = ""
     if too_old:
         too_old_data = "\nLast call to get_message for recently out of date mirrors:\n" + "\n".join(

tools/generate-integration-docs-screenshot

@@ -129,8 +129,7 @@ def send_bot_payload_message(bot: UserProfile, integration: WebhookIntegration,
         data = ''
 
     headers = get_requests_headers(integration.name, fixture_name)
-    if config.custom_headers:
+    headers.update(config.custom_headers)
-        headers.update(config.custom_headers)
     if config.use_basic_auth:
         credentials = base64.b64encode(f'{bot.email}:{bot.api_key}'.encode('utf8')).decode('utf8')
         auth = f'basic {credentials}'
@@ -140,8 +139,7 @@ def send_bot_payload_message(bot: UserProfile, integration: WebhookIntegration,
     stream = integration.stream_name or 'devel'
     url = f"{bot.bot_owner.realm.uri}/{integration.url}"
     params = {'api_key': bot.api_key, 'stream': stream}
-    if config.extra_params:
+    params.update(config.extra_params)
-        params.update(config.extra_params)
 
     extra_args = {}
     if not json_fixture and data:

tools/lib/html_branches.py

@@ -1,6 +1,6 @@
 import re
 from collections import defaultdict
-from typing import Dict, List, Optional, Set
+from typing import Dict, List, Optional, Sequence, Set
 
 from .template_parser import FormattedException, Token, tokenize
 
@@ -132,12 +132,9 @@ def html_branches(text: str, fn: Optional[str] = None) -> List[HtmlTreeBranch]:
     tree = html_tag_tree(text, fn)
     branches: List[HtmlTreeBranch] = []
 
-    def walk(node: Node, tag_info_list: Optional[List[TagInfo]] = None) -> None:
+    def walk(node: Node, tag_info_list: Sequence[TagInfo] = []) -> None:
         info = get_tag_info(node.token)
-        if tag_info_list is None:
+        tag_info_list = [*tag_info_list, info]
-            tag_info_list = [info]
-        else:
-            tag_info_list = tag_info_list[:] + [info]
 
         if node.children:
             for child in node.children:
@@ -147,7 +144,7 @@ def html_branches(text: str, fn: Optional[str] = None) -> List[HtmlTreeBranch]:
             branches.append(tree_branch)
 
     for node in tree.children:
-        walk(node, None)
+        walk(node, [])
 
     return branches
 

tools/run-dev.py

@@ -6,6 +6,7 @@ import signal
 import subprocess
 import sys
 import traceback
+from typing import Any, Callable, Generator, List, Sequence
 from urllib.parse import urlunparse
 
 # check for the venv
@@ -18,7 +19,6 @@ from tornado.ioloop import IOLoop
 
 TOOLS_DIR = os.path.dirname(os.path.abspath(__file__))
 sys.path.insert(0, os.path.dirname(TOOLS_DIR))
-from typing import Any, Callable, Generator, List, Optional
 
 from tools.lib.test_script import assert_provisioning_status_ok
 
@@ -212,9 +212,8 @@ class BaseHandler(web.RequestHandler):
     target_port: int
 
     def _add_request_headers(
-        self, exclude_lower_headers_list: Optional[List[str]] = None,
+        self, exclude_lower_headers_list: Sequence[str] = [],
     ) -> httputil.HTTPHeaders:
-        exclude_lower_headers_list = exclude_lower_headers_list or []
         headers = httputil.HTTPHeaders()
         for header, v in self.request.headers.get_all():
             if header.lower() not in exclude_lower_headers_list:

zerver/data_import/import_util.py

@@ -3,7 +3,7 @@ import os
 import random
 import shutil
 import traceback
-from typing import Any, Callable, Dict, Iterable, List, Optional, Set, Tuple, TypeVar
+from typing import AbstractSet, Any, Callable, Dict, Iterable, List, Optional, Set, Tuple, TypeVar
 
 import requests
 import ujson
@@ -363,12 +363,9 @@ def build_usermessages(zerver_usermessage: List[ZerverFieldsT],
                        mentioned_user_ids: List[int],
                        message_id: int,
                        is_private: bool,
-                       long_term_idle: Optional[Set[int]]=None) -> Tuple[int, int]:
+                       long_term_idle: AbstractSet[int] = set()) -> Tuple[int, int]:
     user_ids = subscriber_map.get(recipient_id, set())
 
-    if long_term_idle is None:
-        long_term_idle = set()
-
     user_messages_created = 0
     user_messages_skipped = 0
     if user_ids:

zerver/lib/actions.py

@@ -1059,7 +1059,7 @@ class RecipientInfoResult(TypedDict):
 def get_recipient_info(recipient: Recipient,
                        sender_id: int,
                        stream_topic: Optional[StreamTopicTarget],
-                       possibly_mentioned_user_ids: Optional[Set[int]]=None,
+                       possibly_mentioned_user_ids: AbstractSet[int]=set(),
                        possible_wildcard_mention: bool=True) -> RecipientInfoResult:
     stream_push_user_ids: Set[int] = set()
     stream_email_user_ids: Set[int] = set()
@@ -1151,14 +1151,13 @@ def get_recipient_info(recipient: Recipient,
     message_to_user_id_set = set(message_to_user_ids)
 
     user_ids = set(message_to_user_id_set)
-    if possibly_mentioned_user_ids:
+    # Important note: Because we haven't rendered bugdown yet, we
-        # Important note: Because we haven't rendered bugdown yet, we
+    # don't yet know which of these possibly-mentioned users was
-        # don't yet know which of these possibly-mentioned users was
+    # actually mentioned in the message (in other words, the
-        # actually mentioned in the message (in other words, the
+    # mention syntax might have been in a code block or otherwise
-        # mention syntax might have been in a code block or otherwise
+    # escaped).  `get_ids_for` will filter these extra user rows
-        # escaped).  `get_ids_for` will filter these extra user rows
+    # for our data structures not related to bots
-        # for our data structures not related to bots
+    user_ids |= possibly_mentioned_user_ids
-        user_ids |= possibly_mentioned_user_ids
 
     if user_ids:
         query = UserProfile.objects.filter(
@@ -2759,7 +2758,7 @@ def get_last_message_id() -> int:
 SubT = Tuple[List[Tuple[UserProfile, Stream]], List[Tuple[UserProfile, Stream]]]
 def bulk_add_subscriptions(streams: Iterable[Stream],
                            users: Iterable[UserProfile],
-                           color_map: Optional[Dict[str, str]]=None,
+                           color_map: Mapping[str, str]={},
                            from_stream_creation: bool=False,
                            acting_user: Optional[UserProfile]=None) -> SubT:
     users = list(users)
@@ -2799,7 +2798,7 @@ def bulk_add_subscriptions(streams: Iterable[Stream],
 
     subs_to_add: List[Tuple[Subscription, Stream]] = []
     for (user_profile, recipient_id, stream) in new_subs:
-        if color_map is not None and stream.name in color_map:
+        if stream.name in color_map:
             color = color_map[stream.name]
         else:
             color = pick_color(user_profile, subs_by_user[user_profile.id])

zerver/lib/bugdown/api_arguments_table_generator.py

@@ -1,7 +1,7 @@
 import json
 import os
 import re
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, List, Mapping
 
 import markdown
 from django.utils.html import escape as escape_html
@@ -14,9 +14,7 @@ REGEXP = re.compile(r'\{generate_api_arguments_table\|\s*(.+?)\s*\|\s*(.+)\s*\}'
 
 
 class MarkdownArgumentsTableGenerator(Extension):
-    def __init__(self, configs: Optional[Dict[str, Any]]=None) -> None:
+    def __init__(self, configs: Mapping[str, Any] = {}) -> None:
-        if configs is None:
-            configs = {}
         self.config = {
             'base_path': ['.', 'Default location from which to evaluate relative paths for the JSON files.'],
         }

zerver/lib/bugdown/api_return_values_table_generator.py

@@ -1,5 +1,5 @@
 import re
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, List, Mapping, Optional
 
 import markdown
 from markdown.extensions import Extension
@@ -11,7 +11,7 @@ REGEXP = re.compile(r'\{generate_return_values_table\|\s*(.+?)\s*\|\s*(.+)\s*\}'
 
 
 class MarkdownReturnValuesTableGenerator(Extension):
-    def __init__(self, configs: Optional[Dict[str, Any]]=None) -> None:
+    def __init__(self, configs: Mapping[str, Any] = {}) -> None:
         self.config: Dict[str, Any] = {}
 
     def extendMarkdown(self, md: markdown.Markdown, md_globals: Dict[str, Any]) -> None:

zerver/lib/bugdown/fenced_code.py

@@ -76,7 +76,7 @@ Dependencies:
 
 """
 import re
-from typing import Any, Dict, Iterable, List, MutableSequence, Optional
+from typing import Any, Dict, Iterable, List, Mapping, MutableSequence, Optional
 
 import markdown
 from django.utils.html import escape
@@ -128,9 +128,7 @@ CODE_VALIDATORS = {
 }
 
 class FencedCodeExtension(markdown.Extension):
-    def __init__(self, config: Optional[Dict[str, Any]]=None) -> None:
+    def __init__(self, config: Mapping[str, Any] = {}) -> None:
-        if config is None:
-            config = {}
         self.config = {
             'run_content_validators': [
                 config.get('run_content_validators', False),

zerver/lib/html_to_text.py

@@ -1,4 +1,4 @@
-from typing import Dict, Optional
+from typing import Mapping
 
 from bs4 import BeautifulSoup
 from django.http import HttpRequest
@@ -7,7 +7,7 @@ from django.utils.html import escape
 from zerver.lib.cache import cache_with_key, open_graph_description_cache_key
 
 
-def html_to_text(content: str, tags: Optional[Dict[str, str]]=None) -> str:
+def html_to_text(content: str, tags: Mapping[str, str] = {'p': ' | '}) -> str:
     bs = BeautifulSoup(content, features='lxml')
     # Skip any admonition (warning) blocks, since they're
     # usually something about users needing to be an
@@ -21,8 +21,6 @@ def html_to_text(content: str, tags: Optional[Dict[str, str]]=None) -> str:
         tag.clear()
 
     text = ''
-    if tags is None:
-        tags = {'p': ' | '}
     for element in bs.find_all(tags.keys()):
         # Ignore empty elements
         if not element.text:

zerver/lib/integrations.py

@@ -1,6 +1,6 @@
 import os
-from dataclasses import dataclass
+from dataclasses import dataclass, field
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional, Sequence, Tuple
 
 from django.conf.urls import url
 from django.contrib.staticfiles.storage import staticfiles_storage
@@ -56,7 +56,7 @@ class Integration:
                  logo: Optional[str]=None, secondary_line_text: Optional[str]=None,
                  display_name: Optional[str]=None, doc: Optional[str]=None,
                  stream_name: Optional[str]=None, legacy: bool=False,
-                 config_options: Optional[List[Tuple[str, str, Validator]]]=None) -> None:
+                 config_options: Sequence[Tuple[str, str, Validator]]=[]) -> None:
         self.name = name
         self.client_name = client_name
         self.secondary_line_text = secondary_line_text
@@ -66,8 +66,6 @@ class Integration:
         # Note: Currently only incoming webhook type bots use this list for
         # defining how the bot's BotConfigData should be. Embedded bots follow
         # a different approach.
-        if config_options is None:
-            config_options = []
         self.config_options = config_options
 
         for category in categories:
@@ -160,7 +158,7 @@ class WebhookIntegration(Integration):
                  function: Optional[str]=None, url: Optional[str]=None,
                  display_name: Optional[str]=None, doc: Optional[str]=None,
                  stream_name: Optional[str]=None, legacy: bool=False,
-                 config_options: Optional[List[Tuple[str, str, Validator]]]=None) -> None:
+                 config_options: Sequence[Tuple[str, str, Validator]]=[]) -> None:
         if client_name is None:
             client_name = self.DEFAULT_CLIENT_NAME.format(name=name.title())
         super().__init__(
@@ -210,9 +208,9 @@ class ScreenshotConfig:
     bot_name: Optional[str] = None
     payload_as_query_param: bool = False
     payload_param_name: str = 'payload'
-    extra_params: Optional[Dict[str, str]] = None
+    extra_params: Dict[str, str] = field(default_factory=dict)
     use_basic_auth: bool = False
-    custom_headers: Optional[Dict[str, str]] = None
+    custom_headers: Dict[str, str] = field(default_factory=dict)
 
 def get_fixture_and_image_paths(integration: WebhookIntegration,
                                 screenshot_config: ScreenshotConfig) -> Tuple[str, str]:

zerver/lib/remote_server.py

@@ -1,6 +1,6 @@
 import logging
 import urllib
-from typing import Any, Dict, List, Optional, Tuple, Union
+from typing import Any, Dict, List, Mapping, Tuple, Union
 
 import requests
 import ujson
@@ -24,7 +24,7 @@ class PushNotificationBouncerRetryLaterError(JsonableError):
 def send_to_push_bouncer(method: str,
                          endpoint: str,
                          post_data: Union[str, Dict[str, Any]],
-                         extra_headers: Optional[Dict[str, Any]]=None) -> Dict[str, Any]:
+                         extra_headers: Mapping[str, Any] = {}) -> Dict[str, Any]:
     """While it does actually send the notice, this function has a lot of
     code and comments around error handling for the push notifications
     bouncer.  There are several classes of failures, each with its own
@@ -47,8 +47,7 @@ def send_to_push_bouncer(method: str,
                                            settings.ZULIP_ORG_KEY)
 
     headers = {"User-agent": f"ZulipServer/{ZULIP_VERSION}"}
-    if extra_headers is not None:
+    headers.update(extra_headers)
-        headers.update(extra_headers)
 
     try:
         res = requests.request(method,

zerver/lib/request.py

@@ -1,7 +1,19 @@
 from collections import defaultdict
 from functools import wraps
 from types import FunctionType
-from typing import Any, Callable, Dict, Generic, List, Optional, TypeVar, Union, cast, overload
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Generic,
+    List,
+    Optional,
+    Sequence,
+    TypeVar,
+    Union,
+    cast,
+    overload,
+)
 
 import ujson
 from django.http import HttpRequest, HttpResponse
@@ -69,7 +81,7 @@ class _REQ(Generic[ResultT]):
         argument_type: Optional[str] = None,
         intentionally_undocumented: bool=False,
         documentation_pending: bool=False,
-        aliases: Optional[List[str]] = None,
+        aliases: Sequence[str] = [],
         path_only: bool=False
     ) -> None:
         """whence: the name of the request variable that should be used
@@ -134,7 +146,7 @@ def REQ(
     default: ResultT = ...,
     intentionally_undocumented: bool = ...,
     documentation_pending: bool = ...,
-    aliases: Optional[List[str]] = ...,
+    aliases: Sequence[str] = ...,
     path_only: bool = ...
 ) -> ResultT:
     ...
@@ -148,7 +160,7 @@ def REQ(
     validator: Validator,
     intentionally_undocumented: bool = ...,
     documentation_pending: bool = ...,
-    aliases: Optional[List[str]] = ...,
+    aliases: Sequence[str] = ...,
     path_only: bool = ...
 ) -> ResultT:
     ...
@@ -162,7 +174,7 @@ def REQ(
     str_validator: Optional[Validator] = ...,
     intentionally_undocumented: bool = ...,
     documentation_pending: bool = ...,
-    aliases: Optional[List[str]] = ...,
+    aliases: Sequence[str] = ...,
     path_only: bool = ...
 ) -> str:
     ...
@@ -176,7 +188,7 @@ def REQ(
     str_validator: Optional[Validator] = ...,
     intentionally_undocumented: bool = ...,
     documentation_pending: bool = ...,
-    aliases: Optional[List[str]] = ...,
+    aliases: Sequence[str] = ...,
     path_only: bool = ...
 ) -> Optional[str]:
     ...
@@ -191,7 +203,7 @@ def REQ(
     argument_type: Literal["body"],
     intentionally_undocumented: bool = ...,
     documentation_pending: bool = ...,
-    aliases: Optional[List[str]] = ...,
+    aliases: Sequence[str] = ...,
     path_only: bool = ...
 ) -> ResultT:
     ...
@@ -207,7 +219,7 @@ def REQ(
     argument_type: Optional[str] = None,
     intentionally_undocumented: bool=False,
     documentation_pending: bool=False,
-    aliases: Optional[List[str]] = None,
+    aliases: Sequence[str] = [],
     path_only: bool = False
 ) -> ResultT:
     return cast(ResultT, _REQ(
@@ -295,8 +307,7 @@ def has_request_variables(view_func: ViewFuncT) -> ViewFuncT:
                 raise Exception(_("Invalid argument type"))
 
             post_var_names = [param.post_var_name]
-            if param.aliases:
+            post_var_names += param.aliases
-                post_var_names += param.aliases
 
             default_assigned = False
 

zerver/lib/response.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Optional
+from typing import Any, List, Mapping, Optional
 
 import ujson
 from django.http import HttpResponse, HttpResponseNotAllowed
@@ -37,15 +37,14 @@ def json_method_not_allowed(methods: List[str]) -> HttpResponseNotAllowed:
 
 def json_response(res_type: str="success",
                   msg: str="",
-                  data: Optional[Dict[str, Any]]=None,
+                  data: Mapping[str, Any]={},
                   status: int=200) -> HttpResponse:
     content = {"result": res_type, "msg": msg}
-    if data is not None:
+    content.update(data)
-        content.update(data)
     return HttpResponse(content=ujson.dumps(content) + "\n",
                         content_type='application/json', status=status)
 
-def json_success(data: Optional[Dict[str, Any]]=None) -> HttpResponse:
+def json_success(data: Mapping[str, Any]={}) -> HttpResponse:
     return json_response(data=data)
 
 def json_response_from_error(exception: JsonableError) -> HttpResponse:
@@ -61,5 +60,5 @@ def json_response_from_error(exception: JsonableError) -> HttpResponse:
                          data=exception.data,
                          status=exception.http_status_code)
 
-def json_error(msg: str, data: Optional[Dict[str, Any]]=None, status: int=400) -> HttpResponse:
+def json_error(msg: str, data: Mapping[str, Any]={}, status: int=400) -> HttpResponse:
     return json_response(res_type="error", msg=msg, data=data, status=status)

zerver/lib/send_email.py

@@ -55,7 +55,7 @@ class FromAddress:
 def build_email(template_prefix: str, to_user_ids: Optional[List[int]]=None,
                 to_emails: Optional[List[str]]=None, from_name: Optional[str]=None,
                 from_address: Optional[str]=None, reply_to_email: Optional[str]=None,
-                language: Optional[str]=None, context: Optional[Dict[str, Any]]=None,
+                language: Optional[str]=None, context: Mapping[str, Any]={},
                 ) -> EmailMultiAlternatives:
     # Callers should pass exactly one of to_user_id and to_email.
     assert (to_user_ids is None) ^ (to_emails is None)
@@ -63,14 +63,12 @@ def build_email(template_prefix: str, to_user_ids: Optional[List[int]]=None,
         to_users = [get_user_profile_by_id(to_user_id) for to_user_id in to_user_ids]
         to_emails = [formataddr((to_user.full_name, to_user.delivery_email)) for to_user in to_users]
 
-    if context is None:
+    context = {
-        context = {}
+        **context,
-
-    context.update({
         'support_email': FromAddress.SUPPORT,
         'email_images_base_uri': settings.ROOT_DOMAIN_URI + '/static/images/emails',
         'physical_address': settings.PHYSICAL_ADDRESS,
-    })
+    }
 
     def render_templates() -> Tuple[str, str, str]:
         email_subject = loader.render_to_string(template_prefix + '.subject.txt',

zerver/openapi/python_examples.py

@@ -1058,18 +1058,18 @@ def test_invalid_stream_error(client: Client) -> None:
 
 
 # SETUP METHODS FOLLOW
-def test_against_fixture(result: Dict[str, Any], fixture: Dict[str, Any], check_if_equal: Optional[Iterable[str]] = [], check_if_exists: Optional[Iterable[str]] = []) -> None:
+def test_against_fixture(result: Dict[str, Any], fixture: Dict[str, Any], check_if_equal: Optional[Iterable[str]] = None, check_if_exists: Optional[Iterable[str]] = None) -> None:
     assertLength(result, fixture)
 
-    if not check_if_equal and not check_if_exists:
+    if check_if_equal is None and check_if_exists is None:
         for key, value in fixture.items():
             assertEqual(key, result, fixture)
 
-    if check_if_equal:
+    if check_if_equal is not None:
         for key in check_if_equal:
             assertEqual(key, result, fixture)
 
-    if check_if_exists:
+    if check_if_exists is not None:
         for key in check_if_exists:
             assertIn(key, result)
 

zerver/templatetags/app_filters.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Optional
+from typing import Any, List, Mapping, Optional
 
 import markdown
 import markdown.extensions.admonition
@@ -75,7 +75,7 @@ docs_without_macros = [
 @items_tuple_to_dict
 @register.filter(name='render_markdown_path', is_safe=True)
 def render_markdown_path(markdown_file_path: str,
-                         context: Optional[Dict[Any, Any]]=None,
+                         context: Mapping[str, Any]={},
                          pure_markdown: bool=False) -> str:
     """Given a path to a markdown file, return the rendered html.
 
@@ -83,9 +83,6 @@ def render_markdown_path(markdown_file_path: str,
     trusted; it is intended to be used for documentation, not user
     data."""
 
-    if context is None:
-        context = {}
-
     # We set this global hackishly
     from zerver.lib.bugdown.help_settings_links import set_relative_settings_links
     set_relative_settings_links(bool(context.get('html_settings_links')))

zerver/tests/test_auth_backends.py

@@ -140,12 +140,10 @@ class AuthBackendTest(ZulipTestCase):
 
         return username
 
-    def verify_backend(self, backend: Any, good_kwargs: Optional[Dict[str, Any]]=None, bad_kwargs: Optional[Dict[str, Any]]=None) -> None:
+    def verify_backend(self, backend: Any, *, good_kwargs: Dict[str, Any], bad_kwargs: Optional[Dict[str, Any]]=None) -> None:
         clear_supported_auth_backends_cache()
         user_profile = self.example_user('hamlet')
 
-        assert good_kwargs is not None
-
         # If bad_kwargs was specified, verify auth fails in that case
         if bad_kwargs is not None:
             self.assertIsNone(backend.authenticate(**bad_kwargs))

zerver/tests/test_email_notifications.py

@@ -1,7 +1,7 @@
 import random
 import re
 from email.utils import formataddr
-from typing import List, Optional
+from typing import List, Sequence
 from unittest.mock import patch
 
 import ldap
@@ -221,7 +221,7 @@ class TestMissedMessages(ZulipTestCase):
     def _test_cases(self, msg_id: int, verify_body_include: List[str], email_subject: str,
                     send_as_user: bool, verify_html_body: bool=False,
                     show_message_content: bool=True,
-                    verify_body_does_not_include: Optional[List[str]]=None,
+                    verify_body_does_not_include: Sequence[str]=[],
                     trigger: str='') -> None:
         othello = self.example_user('othello')
         hamlet = self.example_user('hamlet')
@@ -248,9 +248,8 @@ class TestMissedMessages(ZulipTestCase):
         else:
             for text in verify_body_include:
                 self.assertIn(text, self.normalize_string(msg.body))
-        if verify_body_does_not_include is not None:
+        for text in verify_body_does_not_include:
-            for text in verify_body_does_not_include:
+            self.assertNotIn(text, self.normalize_string(msg.body))
-                self.assertNotIn(text, self.normalize_string(msg.body))
 
     def _realm_name_in_missed_message_email_subject(self, realm_name_in_notifications: bool) -> None:
         msg_id = self.send_personal_message(

zerver/tests/test_subs.py

@@ -1,6 +1,6 @@
 import random
 from datetime import timedelta
-from typing import Any, Dict, List, Mapping, Optional, Set, Union
+from typing import Any, Dict, List, Mapping, Optional, Sequence, Set, Union
 from unittest import mock
 
 import ujson
@@ -976,7 +976,7 @@ class StreamAdminTest(ZulipTestCase):
     def attempt_unsubscribe_of_principal(self, query_count: int, target_users: List[UserProfile],
                                          is_admin: bool=False, is_subbed: bool=True, invite_only: bool=False,
                                          target_users_subbed: bool=True, using_legacy_emails: bool=False,
-                                         other_sub_users: Optional[List[UserProfile]]=None) -> HttpResponse:
+                                         other_sub_users: Sequence[UserProfile]=[]) -> HttpResponse:
 
         # Set up the main user, who is in most cases an admin.
         if is_admin:
@@ -1004,9 +1004,8 @@ class StreamAdminTest(ZulipTestCase):
         if target_users_subbed:
             for user in target_users:
                 self.subscribe(user, stream_name)
-        if other_sub_users:
+        for user in other_sub_users:
-            for user in other_sub_users:
+            self.subscribe(user, stream_name)
-                self.subscribe(user, stream_name)
 
         with queries_captured() as queries:
             result = self.client_delete(

zerver/views/report.py

@@ -1,7 +1,7 @@
 # System documented in https://zulip.readthedocs.io/en/latest/subsystems/logging.html
 import logging
 import subprocess
-from typing import Any, Dict, Optional
+from typing import Any, Dict, Mapping, Optional
 
 from django.conf import settings
 from django.http import HttpRequest, HttpResponse
@@ -89,14 +89,13 @@ def report_unnarrow_times(request: HttpRequest, user_profile: UserProfile,
 def report_error(request: HttpRequest, user_profile: UserProfile, message: str=REQ(),
                  stacktrace: str=REQ(), ui_message: bool=REQ(validator=check_bool),
                  user_agent: str=REQ(), href: str=REQ(), log: str=REQ(),
-                 more_info: Optional[Dict[str, Any]]=REQ(validator=check_dict([]), default=None),
+                 more_info: Mapping[str, Any]=REQ(validator=check_dict([]), default={}),
                  ) -> HttpResponse:
     """Accepts an error report and stores in a queue for processing.  The
     actual error reports are later handled by do_report_error"""
     if not settings.BROWSER_ERROR_REPORTING:
         return json_success()
-    if more_info is None:
+    more_info = dict(more_info)
-        more_info = {}
 
     js_source_map = get_js_source_map()
     if js_source_map:

zerver/webhooks/trello/view/board_actions.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Mapping, Optional, Tuple
+from typing import Any, Mapping, Optional, Tuple
 
 from zerver.lib.exceptions import UnexpectedWebhookEventType
 
@@ -71,9 +71,10 @@ def get_change_name_body(payload: Mapping[str, Any], action_type: str) -> str:
 
 def fill_appropriate_message_content(payload: Mapping[str, Any],
                                      action_type: str,
-                                     data: Optional[Dict[str, Any]]=None) -> str:
+                                     data: Mapping[str, Any] = {}) -> str:
-    data = {} if data is None else data
+    data = dict(data)
-    data['board_url_template'] = data.get('board_url_template', get_filled_board_url_template(payload))
+    if 'board_url_template' not in data:
+        data['board_url_template'] = get_filled_board_url_template(payload)
     message_body = get_message_body(action_type)
     return message_body.format(**data)
 

zerver/webhooks/trello/view/card_actions.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Mapping, Optional, Tuple
+from typing import Any, Mapping, Optional, Tuple
 
 from zerver.lib.exceptions import UnexpectedWebhookEventType
 
@@ -205,9 +205,10 @@ def get_body_by_action_type_without_data(payload: Mapping[str, Any], action_type
 
 def fill_appropriate_message_content(payload: Mapping[str, Any],
                                      action_type: str,
-                                     data: Optional[Dict[str, Any]]=None) -> str:
+                                     data: Mapping[str, Any] = {}) -> str:
-    data = {} if data is None else data
+    data = dict(data)
-    data['card_url_template'] = data.get('card_url_template', get_filled_card_url_template(payload))
+    if 'card_url_template' not in data:
+        data['card_url_template'] = get_filled_card_url_template(payload)
     message_body = get_message_body(action_type)
     return message_body.format(**data)