check typing with mypy

This change adds tox configuration to run mypy, and updates the type
information so test passes.

---

Co-Authored-By: Ian Campbell <ipcampbell@gmail.com>

Author: terencehonles

anymail/__init__.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from ._version import VERSION, __version__
 
 __all__ = [

anymail/_idna.py

@@ -1,4 +1,6 @@
 # Pre-packaged IDNA_ENCODER options
+from __future__ import annotations
+
 import idna
 
 from anymail.exceptions import AnymailImproperlyInstalled, _LazyError

anymail/_version.py

@@ -1,6 +1,8 @@
 # Don't import this file directly (unless you are a build system).
 # Instead, load version info from the package root.
 
+from __future__ import annotations
+
 #: major.minor or major.minor.patch (optionally with .devN suffix)
 __version__ = "14.0"
 

anymail/apps.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from django.apps import AppConfig
 from django.core import checks
 

anymail/backends/amazon_ses.py

@@ -1,6 +1,9 @@
+from __future__ import annotations
+
 import email.charset
 import email.encoders
 import email.policy
+from typing import Any
 
 from requests.structures import CaseInsensitiveDict
 
@@ -165,6 +168,7 @@ def init_payload(self):
         try:
             for field in address_fields:
                 addresses = getattr(self.message, field)
+                idna_encoded_addresses: str | list[str]
                 idna_encoded_addresses = [
                     address.format(idna_encode=self.backend.idna_encode)
                     for address in parse_address_list(addresses, field)
@@ -364,7 +368,7 @@ class AmazonSESV2SendBulkEmailPayload(AmazonSESBasePayload):
     def init_payload(self):
         super().init_payload()
         # late-bind in finalize_payload:
-        self.recipients = {"to": [], "cc": [], "bcc": []}
+        self.recipients = dict[str, list[Any]](to=[], cc=[], bcc=[])
         self.merge_data = {}
         self.headers = {}
         self.merge_headers = {}

anymail/backends/base.py

@@ -1,5 +1,8 @@
+from __future__ import annotations
+
 import json
 from datetime import date, datetime, timezone
+from typing import Any
 
 from django.core.mail.backends.base import BaseEmailBackend
 from django.utils.module_loading import import_string
@@ -20,6 +23,7 @@
 from ..utils import (
     UNSET,
     Attachment,
+    UnsetType,
     concat_lists,
     force_non_lazy,
     force_non_lazy_dict,
@@ -334,7 +338,9 @@ def __init__(self, message, defaults, backend):
         self.defaults = defaults
         self.backend = backend
         self.esp_name = backend.esp_name
-        self._batch_attrs_used = {attr: UNSET for attr in self.batch_attrs}
+        self._batch_attrs_used: dict[str, Any | UnsetType] = {
+            attr: UNSET for attr in self.batch_attrs
+        }
 
         self.init_payload()
 
@@ -358,7 +364,7 @@ def __init__(self, message, defaults, backend):
                         converter = getattr(self, converter)
                     if converter in (parse_address_list, parse_single_address):
                         # hack to include field name in error message
-                        value = converter(value, field=attr)
+                        value = converter(value, field=attr)  # type: ignore[call-arg]
                     else:
                         value = converter(value)
             if value is not UNSET:
@@ -663,7 +669,7 @@ def set_esp_extra(self, extra):
     # Helpers for concrete implementations
     #
 
-    def serialize_json(self, data):
+    def serialize_json(self, data) -> str:
         """Returns data serialized to json, raising appropriate errors.
 
         Essentially json.dumps with added context in any errors.

anymail/backends/base_requests.py

@@ -1,3 +1,6 @@
+from __future__ import annotations
+
+from typing import cast
 from urllib.parse import urljoin
 
 import requests
@@ -10,6 +13,8 @@
 
 
 class AnymailRequestsBackend(AnymailBaseBackend):
+    session: requests.Session | None
+
     """
     Base Anymail email backend for ESPs that use an HTTP API via requests
     """
@@ -73,7 +78,7 @@ def create_session(self):
         session.headers["User-Agent"] = "django-anymail/{version}-{esp} {orig}".format(
             esp=self.esp_name.lower(),
             version=__version__,
-            orig=session.headers.get("User-Agent", ""),
+            orig=cast(str, session.headers.get("User-Agent", "")),
         )
 
         if self.debug_api_requests:
@@ -93,6 +98,7 @@ def post_to_esp(self, payload, message):
         params = payload.get_request_params(self.api_url)
         params.setdefault("timeout", self.timeout)
         try:
+            assert self.session
             response = self.session.request(**params)
         except requests.RequestException as err:
             # raise an exception that is both AnymailRequestsAPIError

anymail/backends/brevo.py

@@ -1,3 +1,7 @@
+from __future__ import annotations
+
+from typing import Any, Literal
+
 from requests.structures import CaseInsensitiveDict
 
 from ..exceptions import AnymailRequestsAPIError
@@ -103,7 +107,7 @@ def __init__(self, message, defaults, backend, *args, **kwargs):
         http_headers["api-key"] = backend.api_key
         http_headers["Content-Type"] = "application/json"
 
-        super().__init__(
+        super().__init__(  # type: ignore[misc]
             message, defaults, backend, headers=http_headers, *args, **kwargs
         )
 
@@ -125,8 +129,8 @@ def serialize_data(self):
             self.data["messageVersions"] = []
             for to in to_list:
                 to_email = to["email"]
-                version = {"to": [to]}
-                headers = CaseInsensitiveDict()
+                version = dict[str, Any](to=[to])
+                headers = CaseInsensitiveDict[str]()
                 if to_email in self.merge_data:
                     version["params"] = self.merge_data[to_email]
                 if to_email in self.merge_metadata:
@@ -158,7 +162,7 @@ def serialize_data(self):
 
     def email_object(self, email):
         """Converts EmailAddress to Brevo API object with workarounds"""
-        use_rfc2047 = False
+        use_rfc2047: bool | Literal["force"] = False
         # In from/to/cc/bcc, Brevo silently drops the "name" field if it
         # contains both non-ASCII chars and a comma (or other special).
         # In replyTo, Brevo sends the name as 8-bit (unencoded) utf-8.

anymail/backends/console.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import uuid
 
 from django.core.mail.backends.console import EmailBackend as DjangoConsoleBackend

anymail/backends/mailersend.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import mimetypes
 
 from ..exceptions import AnymailRequestsAPIError, AnymailUnsupportedFeature
@@ -127,7 +129,7 @@ def __init__(self, message, defaults, backend, *args, **kwargs):
         self.merge_data = {}  # late bound
         self.merge_global_data = None  # late bound
         self.batch_send_mode = backend.batch_send_mode  # can override in esp_extra
-        super().__init__(message, defaults, backend, headers=headers, *args, **kwargs)
+        super().__init__(message, defaults, backend, headers=headers, *args, **kwargs)  # type: ignore[misc] # noqa: E501
 
     def get_api_endpoint(self):
         if self.is_batch():