Annotate test helpers

tests/fields.py

@@ -1,9 +1,12 @@
 from __future__ import annotations
 
+from typing import Any
+
 from django.db import models
+from django.db.backends.base.base import BaseDatabaseWrapper
 
 
-def mutable_from_db(value):
+def mutable_from_db(value: object) -> Any:
     if value == '':
         return None
     try:
@@ -14,7 +17,7 @@ def mutable_from_db(value):
     return value
 
 
-def mutable_to_db(value):
+def mutable_to_db(value: object) -> str:
     if value is None:
         return ''
     if isinstance(value, list):
@@ -23,12 +26,12 @@ def mutable_to_db(value):
 
 
 class MutableField(models.TextField):
-    def to_python(self, value):
+    def to_python(self, value: object) -> Any:
         return mutable_from_db(value)
 
-    def from_db_value(self, value, expression, connection):
+    def from_db_value(self, value: object, expression: object, connection: BaseDatabaseWrapper) -> Any:
         return mutable_from_db(value)
 
-    def get_db_prep_save(self, value, connection):
+    def get_db_prep_save(self, value: object, connection: BaseDatabaseWrapper) -> str:
         value = super().get_db_prep_save(value, connection)
         return mutable_to_db(value)

tests/models.py

@@ -1,9 +1,10 @@
 from __future__ import annotations
 
-from typing import ClassVar, TypeVar
+from typing import Any, ClassVar, TypeVar, overload
 
 from django.db import models
 from django.db.models import Manager
+from django.db.models.query import QuerySet
 from django.db.models.query_utils import DeferredAttribute
 from django.utils.translation import gettext_lazy as _
 
@@ -45,7 +46,7 @@ class InheritanceManagerTestParent(models.Model):
         on_delete=models.CASCADE)
     objects: ClassVar[InheritanceManager[InheritanceManagerTestParent]] = InheritanceManager()
 
-    def __str__(self):
+    def __str__(self) -> str:
         return "{}({})".format(
             self.__class__.__name__[len('InheritanceManagerTest'):],
             self.pk,
@@ -186,7 +187,7 @@ class Post(models.Model):
     public: ClassVar[QueryManager[Post]] = QueryManager(published=True)
     public_confirmed: ClassVar[QueryManager[Post]] = QueryManager(
         models.Q(published=True) & models.Q(confirmed=True))
-    public_reversed: QueryManager[Post] = QueryManager(
+    public_reversed: ClassVar[QueryManager[Post]] = QueryManager(
         published=True).order_by("-order")
 
     class Meta:
@@ -206,7 +207,6 @@ class SplitFieldAbstractParent(models.Model):
 
 
 class AbstractTracked(models.Model):
-    number: models.IntegerField
 
     class Meta:
         abstract = True
@@ -219,7 +219,7 @@ class Tracked(models.Model):
 
     tracker = FieldTracker()
 
-    def save(self, *args, **kwargs):
+    def save(self, *args: Any, **kwargs: Any) -> None:
         """ No-op save() to ensure that FieldTracker.patch_save() works. """
         super().save(*args, **kwargs)
 
@@ -231,7 +231,7 @@ class TrackerTimeStamped(TimeStampedModel):
 
     tracker = FieldTracker()
 
-    def save(self, *args, **kwargs):
+    def save(self, *args: Any, **kwargs: Any) -> None:
         """ Automatically add "modified" to update_fields."""
         update_fields = kwargs.get('update_fields')
         if update_fields is not None:
@@ -249,7 +249,7 @@ class TrackedFK(models.Model):
 
 class TrackedAbstract(AbstractTracked):
     name = models.CharField(max_length=20)
-    number = models.IntegerField()  # type: ignore[assignment]
+    number = models.IntegerField()
     mutable = MutableField(default=None)
 
     tracker = ModelTracker()
@@ -266,7 +266,7 @@ class TrackedNonFieldAttr(models.Model):
     number = models.FloatField()
 
     @property
-    def rounded(self):
+    def rounded(self) -> int | None:
         return round(self.number) if self.number is not None else None
 
     tracker = FieldTracker(fields=['rounded'])
@@ -355,43 +355,52 @@ class SoftDeletable(SoftDeletableModel):
     all_objects: ClassVar[Manager[SoftDeletable]] = models.Manager()
 
 
-class CustomSoftDeleteQuerySet(SoftDeletableQuerySet):
-    def only_read(self):
+class CustomSoftDeleteQuerySet(SoftDeletableQuerySet[ModelT]):
+    def only_read(self) -> QuerySet[ModelT]:
         return self.filter(is_read=True)
 
 
 class CustomSoftDelete(SoftDeletableModel):
     is_read = models.BooleanField(default=False)
 
-    available_objects = SoftDeletableManager.from_queryset(CustomSoftDeleteQuerySet)()  # type: ignore[misc]
+    available_objects = SoftDeletableManager.from_queryset(CustomSoftDeleteQuerySet)()
 
 
 class StringyDescriptor:
     """
     Descriptor that returns a string version of the underlying integer value.
     """
-    def __init__(self, name):
+    def __init__(self, name: str):
         self.name = name
 
-    def __get__(self, obj, cls=None):
+    @overload
+    def __get__(self, obj: None, cls: type[models.Model] | None = None) -> StringyDescriptor:
+        ...
+
+    @overload
+    def __get__(self, obj: models.Model, cls: type[models.Model]) -> str:
+        ...
+
+    def __get__(self, obj: models.Model | None, cls: type[models.Model] | None = None) -> StringyDescriptor | str:
         if obj is None:
             return self
         if self.name in obj.get_deferred_fields():
             # This queries the database, and sets the value on the instance.
+            assert cls is not None
             fields_map = {f.name: f for f in cls._meta.fields}
             field = fields_map[self.name]
             DeferredAttribute(field=field).__get__(obj, cls)
         return str(obj.__dict__[self.name])
 
-    def __set__(self, obj, value):
+    def __set__(self, obj: object, value: str) -> None:
         obj.__dict__[self.name] = int(value)
 
-    def __delete__(self, obj):
+    def __delete__(self, obj: object) -> None:
         del obj.__dict__[self.name]
 
 
 class CustomDescriptorField(models.IntegerField):
-    def contribute_to_class(self, cls, name, *args, **kwargs):
+    def contribute_to_class(self, cls: type[models.Model], name: str, *args: Any, **kwargs: Any) -> None:
         super().contribute_to_class(cls, name, *args, **kwargs)
         setattr(cls, name, StringyDescriptor(name))