Feature/implement mypy type checking

.github/workflows/mypy.yml

@@ -0,0 +1,22 @@
+---
+name: Run mypy
+on:
+  pull_request:
+  push:
+    branches: ["main", "v[0-9]*"]
+    tags: ["v[0-9]*"]
+  workflow_dispatch:
+jobs:
+  mypy:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: apt update
+        run: sudo apt update
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+      - name: Install Python dependencies
+        run: |
+          python -m pip install --upgrade pip wheel
+          pip install -r requirements-dev.txt
+      - name: MyPy
+        run: mypy .

anymail/backends/sendgrid.py

@@ -1,12 +1,13 @@
 import uuid
 import warnings
+from collections.abc import Mapping
 from email.utils import quote as rfc822_quote
 
 from requests.structures import CaseInsensitiveDict
 
 from ..exceptions import AnymailConfigurationError, AnymailWarning
 from ..message import AnymailRecipientStatus
-from ..utils import BASIC_NUMERIC_TYPES, Mapping, get_anymail_setting, update_deep
+from ..utils import BASIC_NUMERIC_TYPES, get_anymail_setting, update_deep
 from .base_requests import AnymailRequestsBackend, RequestsPayload
 
 

anymail/backends/unisender_go.py

@@ -135,9 +135,8 @@ def __init__(
         http_headers["Content-Type"] = "application/json"
         http_headers["Accept"] = "application/json"
         http_headers["X-API-KEY"] = backend.api_key
-        super().__init__(
-            message, defaults, backend, headers=http_headers, *args, **kwargs
-        )
+        kwargs["headers"] = http_headers
+        super().__init__(message, defaults, backend, *args, **kwargs)
 
     def get_api_endpoint(self) -> str:
         return "email/send.json"
@@ -297,7 +296,9 @@ def set_send_at(self, send_at: datetime | str) -> None:
             # "Date and time in the format “YYYY-MM-DD hh:mm:ss” in the UTC time zone."
             # If send_at is a datetime, it's guaranteed to be aware, but maybe not UTC.
             # Convert to UTC, then strip tzinfo to avoid isoformat "+00:00" at end.
-            send_at_utc = send_at.astimezone(timezone.utc).replace(tzinfo=None)
+            send_at_utc = send_at.astimezone(  # type:ignore[union-attr]
+                timezone.utc
+            ).replace(tzinfo=None)
             send_at_formatted = send_at_utc.isoformat(sep=" ", timespec="seconds")
             assert len(send_at_formatted) == 19
         except (AttributeError, TypeError):

anymail/exceptions.py

@@ -86,7 +86,7 @@ class AnymailAPIError(AnymailError):
     """Exception for unsuccessful response from ESP's API."""
 
 
-class AnymailRequestsAPIError(AnymailAPIError, HTTPError):
+class AnymailRequestsAPIError(AnymailAPIError, HTTPError):  # type: ignore[misc]
     """Exception for unsuccessful response from a requests API."""
 
     def __init__(self, *args, **kwargs):

anymail/types.py

@@ -0,0 +1 @@
+AnymailRecipientsType = list[dict[str, dict[str, str]]]

anymail/webhooks/base.py

@@ -1,5 +1,7 @@
+import typing
 import warnings
 
+from django.dispatch import Signal
 from django.http import HttpResponse
 from django.utils.crypto import constant_time_compare
 from django.utils.decorators import method_decorator
@@ -30,7 +32,7 @@ def __init__(self, **kwargs):
     # Subclass implementation:
 
     # Where to send events: either ..signals.inbound or ..signals.tracking
-    signal = None
+    signal: typing.Optional[Signal] = None
 
     def validate_request(self, request):
         """Check validity of webhook post, or raise AnymailWebhookValidationFailure.

anymail/webhooks/postal.py

@@ -35,11 +35,11 @@
             missing_package="cryptography", install_extra="postal"
         )
     )
-    serialization = error
-    hashes = error
+    serialization = error  # type: ignore[assignment]
+    hashes = error  # type: ignore[assignment]
     default_backend = error
-    padding = error
-    InvalidSignature = object
+    padding = error  # type: ignore[assignment]
+    InvalidSignature = object  # type:ignore[assignment,misc]
 
 
 class PostalBaseWebhookView(AnymailBaseWebhookView):

mypy.ini

@@ -0,0 +1,24 @@
+[mypy]
+plugins = mypy_django_plugin.main
+# TODO: Check all code in the future
+check_untyped_defs = False
+disallow_any_generics = False
+disallow_incomplete_defs = False
+disallow_subclassing_any = False
+disallow_untyped_calls = False
+disallow_untyped_defs = False
+ignore_missing_imports = True
+no_implicit_optional = True
+no_implicit_reexport = True
+strict = True
+warn_return_any = False
+# TODO: Remove this exception in the future
+disable_error_code = var-annotated
+exclude = docs
+
+[mypy.plugins.django-stubs]
+django_settings_module = "tests.test_settings.settings_5_0"
+
+# TODO: Type check tests in the future
+[mypy-tests.*]
+ignore_errors = True

requirements-dev.txt

@@ -1,5 +1,9 @@
 # Requirements for developing (not just using) the package
 
+django-stubs
 hatch
+mypy
 pre-commit
+requests
 tox<4
+types-requests

tests/test_sparkpost_backend.py

@@ -49,7 +49,7 @@ class SparkPostBackendMockAPITestCase(RequestsBackendMockAPITestCase):
     def setUp(self):
         super().setUp()
         # Simple message useful for many tests
-        self.message = mail.EmailMultiAlternatives(
+        self.message = AnymailMessage(
             "Subject", "Text Body", "from@example.com", ["to@example.com"]
         )