zproject: Fix typing errors under the zproject directory.

This fixes error found with django-stubs and it is a part of #18777.

Note that there are various remaining errors that need to be fixed in
upstream or elsewhere in our codebase.

zproject/backends.py

@@ -301,7 +301,7 @@ class ZulipAuthMixin:
     """
 
     name = "undefined"
-    _logger = None
+    _logger: Optional[logging.Logger] = None
 
     @property
     def logger(self) -> logging.Logger:

zproject/computed_settings.py

@@ -3,7 +3,6 @@ import sys
 import time
 import warnings
 from copy import deepcopy
-from pathlib import PosixPath
 from typing import Any, Dict, List, Tuple, Union
 from urllib.parse import urljoin
 
@@ -165,7 +164,7 @@ ALLOWED_HOSTS += REALM_HOSTS.values()
 
 
 class TwoFactorLoader(app_directories.Loader):
-    def get_dirs(self) -> List[PosixPath]:
+    def get_dirs(self) -> List[Union[bytes, str]]:
         dirs = super().get_dirs()
         return [d for d in dirs if d.match("two_factor/*")]
 

zproject/default_settings.py

@@ -65,7 +65,7 @@ AUTH_LDAP_ALWAYS_UPDATE_USER = False
 # Detailed docs in zproject/dev_settings.py.
 FAKE_LDAP_MODE: Optional[str] = None
 FAKE_LDAP_NUM_USERS = 8
-AUTH_LDAP_ADVANCED_REALM_ACCESS_CONTROL = None
+AUTH_LDAP_ADVANCED_REALM_ACCESS_CONTROL: Optional[Dict[str, Any]] = None
 
 # Social auth; we support providing values for some of these
 # settings in zulip-secrets.conf instead of settings.py in development.
@@ -138,8 +138,8 @@ DEFAULT_AVATAR_URI = "/static/images/default-avatar.png"
 DEFAULT_LOGO_URI = "/static/images/logo/zulip-org-logo.svg"
 S3_AVATAR_BUCKET = ""
 S3_AUTH_UPLOADS_BUCKET = ""
-S3_REGION = None
-S3_ENDPOINT_URL = None
+S3_REGION: Optional[str] = None
+S3_ENDPOINT_URL: Optional[str] = None
 LOCAL_UPLOADS_DIR: Optional[str] = None
 MAX_FILE_UPLOAD_SIZE = 25
 

zproject/dev_settings.py

@@ -160,7 +160,7 @@ THUMBNAIL_IMAGES = True
 SEARCH_PILLS_ENABLED = bool(os.getenv("SEARCH_PILLS_ENABLED", False))
 
 BILLING_ENABLED = True
-LANDING_PAGE_NAVBAR_MESSAGE = None
+LANDING_PAGE_NAVBAR_MESSAGE: Optional[str] = None
 
 # Test custom TOS template rendering
 TERMS_OF_SERVICE = "corporate/terms.md"
@@ -175,4 +175,4 @@ USE_X_FORWARDED_PORT = True
 # Override the default SAML entity ID
 SOCIAL_AUTH_SAML_SP_ENTITY_ID = "http://localhost:9991"
 
-MEMCACHED_USERNAME = None
+MEMCACHED_USERNAME: Optional[str] = None

zproject/dev_urls.py

@@ -4,7 +4,8 @@ from urllib.parse import urlsplit
 from django.conf import settings
 from django.conf.urls.static import static
 from django.contrib.staticfiles.views import serve as staticfiles_serve
-from django.http import HttpRequest, HttpResponse
+from django.http import HttpRequest
+from django.http.response import FileResponse
 from django.urls import path
 from django.views.generic import TemplateView
 from django.views.static import serve
@@ -110,7 +111,7 @@ if use_prod_static:
     ]
 else:
 
-    def serve_static(request: HttpRequest, path: str) -> HttpResponse:
+    def serve_static(request: HttpRequest, path: str) -> FileResponse:
         response = staticfiles_serve(request, path)
         response["Access-Control-Allow-Origin"] = "*"
         return response

zproject/email_backends.py

@@ -1,11 +1,13 @@
 # https://zulip.readthedocs.io/en/latest/subsystems/email.html#testing-in-a-real-email-client
 import configparser
 import logging
-from typing import List
+from email.message import Message
+from typing import List, MutableSequence, Union
 
 from django.conf import settings
 from django.core.mail import EmailMultiAlternatives
 from django.core.mail.backends.smtp import EmailBackend
+from django.core.mail.message import EmailMessage
 from django.template import loader
 
 
@@ -34,7 +36,7 @@ class EmailLogBackEnd(EmailBackend):
     @staticmethod
     def log_email(email: EmailMultiAlternatives) -> None:
         """Used in development to record sent emails in a nice HTML log"""
-        html_message = "Missing HTML message"
+        html_message: Union[bytes, EmailMessage, Message, str] = "Missing HTML message"
         if len(email.alternatives) > 0:
             html_message = email.alternatives[0][0]
 
@@ -68,12 +70,14 @@ class EmailLogBackEnd(EmailBackend):
 
         for email_message in email_messages:
             html_alternative = list(email_message.alternatives[0])
+            assert isinstance(html_alternative[0], str)
             # Here, we replace the email addresses used in development
             # with chat.zulip.org, so that web email providers like Gmail
             # will be able to fetch the illustrations used in the emails.
             html_alternative[0] = html_alternative[0].replace(
                 localhost_email_images_base_uri, czo_email_images_base_uri
             )
+            assert isinstance(email_message.alternatives, MutableSequence)
             email_message.alternatives[0] = tuple(html_alternative)
 
             email_message.to = [get_forward_address()]

zproject/test_extra_settings.py

@@ -1,5 +1,5 @@
 import os
-from typing import Dict, List, Tuple
+from typing import Dict, List, Optional, Tuple
 
 import ldap
 from django_auth_ldap.config import LDAPSearch
@@ -215,7 +215,7 @@ BIG_BLUE_BUTTON_URL = "https://bbb.example.com/bigbluebutton/"
 # By default two factor authentication is disabled in tests.
 # Explicitly set this to True within tests that must have this on.
 TWO_FACTOR_AUTHENTICATION_ENABLED = False
-PUSH_NOTIFICATION_BOUNCER_URL = None
+PUSH_NOTIFICATION_BOUNCER_URL: Optional[str] = None
 
 THUMBNAIL_IMAGES = True
 
@@ -269,4 +269,4 @@ RATE_LIMITING_RULES: Dict[str, List[Tuple[int, int]]] = {
     "password_reset_form_by_email": [],
 }
 
-FREE_TRIAL_DAYS = None
+FREE_TRIAL_DAYS: Optional[int] = None

zproject/urls.py

@@ -1,4 +1,5 @@
 import os
+from typing import List, Union
 
 from django.conf import settings
 from django.conf.urls import include
@@ -10,6 +11,7 @@ from django.contrib.auth.views import (
     PasswordResetDoneView,
 )
 from django.urls import path
+from django.urls.resolvers import URLPattern, URLResolver
 from django.utils.module_loading import import_string
 from django.views.generic import RedirectView, TemplateView
 
@@ -634,7 +636,7 @@ i18n_urls = [
 ]
 
 # Make a copy of i18n_urls so that they appear without prefix for english
-urls = list(i18n_urls)
+urls: List[Union[URLPattern, URLResolver]] = list(i18n_urls)
 
 # Include the dual-use patterns twice
 urls += [