Configure mypy with django-stubs

This allows mypy to do a lot of type-inference round django-related
code. Should improve how we handle typing errors.

.pre-commit-config.yaml

@@ -18,13 +18,6 @@ repos:
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]
         exclude: docs\/.*
-  - repo: https://github.com/pre-commit/mirrors-mypy
-    rev: "v1.5.1"
-    hooks:
-      - id: mypy
-        additional_dependencies:
-          - types-requests
-        exclude: testapp
   - repo: https://github.com/psf/black
     rev: "23.9.1"
     hooks:

payments/models.py

@@ -94,7 +94,7 @@ def change_status(self, status: PaymentStatus | str, message=""):
         """
         from .signals import status_changed
 
-        self.status = status
+        self.status = status  # type: ignore[assignment]
         self.message = message
         self.save(update_fields=["status", "message"])
         status_changed.send(sender=type(self), instance=self)
@@ -107,7 +107,7 @@ def change_fraud_status(self, status: PaymentStatus, message="", commit=True):
                     status, ", ".join(available_statuses)
                 )
             )
-        self.fraud_status = status
+        self.fraud_status = status  # type: ignore[assignment]
         self.fraud_message = message
         if commit:
             self.save()

payments/stripe/__init__.py

@@ -3,6 +3,7 @@
 import json
 import warnings
 from decimal import Decimal
+from typing import TYPE_CHECKING
 
 import stripe
 
@@ -15,6 +16,9 @@
 from .forms import PaymentForm
 from .providers import StripeProviderV3
 
+if TYPE_CHECKING:
+    from django import forms
+
 
 class StripeProvider(BasicProvider):
     """Provider backend using `Stripe <https://stripe.com/>`_.
@@ -27,7 +31,7 @@ class StripeProvider(BasicProvider):
     :param image: Your logo.
     """
 
-    form_class = ModalPaymentForm
+    form_class: type[forms.Form] = ModalPaymentForm
 
     def __init__(self, public_key, secret_key, image="", name="", **kwargs):
         stripe.api_key = secret_key

pyproject.toml

@@ -40,10 +40,16 @@ braintree = ["braintree>=3.14.0"]
 cybersource = ["suds-community>=0.6"]
 dev = [
     "coverage",
+    "django-stubs[compatible-mypy]",
     "mock",
     "pytest",
     "pytest-cov",
     "pytest-django",
+    "types-braintree",
+    "types-dj-database-url",
+    "types-requests",
+    "types-stripe",
+    "types-xmltodict",
 ]
 docs = ["sphinx_rtd_theme"]
 mercadopago = ["mercadopago>=2.0.0,<3.0.0"]
@@ -62,6 +68,13 @@ exclude_lines = [
     "if TYPE_CHECKING:",
 ]
 
+[tool.mypy]
+ignore_missing_imports = true
+plugins = ["mypy_django_plugin.main"]
+
+[tool.django-stubs]
+django_settings_module = "test_settings"
+
 [tool.pytest.ini_options]
 addopts =[
   "--cov=payments",

tox.ini

@@ -36,6 +36,12 @@ python =
     3.11: py311
     3.12-dev: py312
 
+[testenv:mypy]
+setenv =
+  PYTHONPATH = {env:PATH}/testapp
+extras = {[testenv]extras}
+commands = mypy .
+
 [gh-actions:env]
 DJANGO =
     3.2: dj32