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typing: improve CaptureQueriesContext and test decorators in django.t… #3233

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typing: improve CaptureQueriesContext and test decorators in django.t…
01-Harshit Mar 28, 2026
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Merge branch 'master' into fix/test-util-typing-enhancement
01-Harshit Mar 29, 2026
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25 changes: 13 additions & 12 deletions django-stubs/test/utils.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -12,17 +12,15 @@ from django.conf import LazySettings, Settings
from django.core.checks.registry import CheckRegistry
from django.db.backends.base.base import BaseDatabaseWrapper
from django.db.models.lookups import Lookup, Transform
from django.db.models.query import _SupportsContains
from django.db.models.query_utils import RegisterLookupMixin
from django.test.runner import DiscoverRunner
from django.test.testcases import SimpleTestCase
from typing_extensions import Self, TypeVar, override

_TestClass: TypeAlias = type[SimpleTestCase]

_DecoratedTest: TypeAlias = Callable | _TestClass
_DecoratedTest: TypeAlias = Callable[..., Any] | _TestClass
_DT = TypeVar("_DT", bound=_DecoratedTest)
_C = TypeVar("_C", bound=Callable) # Any callable
_C = TypeVar("_C", bound=Callable[..., Any]) # Any callable
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@UnknownPlatypus UnknownPlatypus Mar 28, 2026

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Updated _DecoratedTest, _C, new_checks, deployment_checks, and filter_func to Callable[..., Any] for better Mypy and Pyright support.

There is no typing improvement, these are equivalent. But it’s slightly better because it would pass mypy no_any_generic check.

However, can we have a more narrow type here or is this the only option?

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@01-Harshit 01-Harshit Mar 28, 2026

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  • Regarding Callable[..., Any], this change does not improve typing precision but satisfies mypy's no_any_generic check. Narrower typing is challenging because decorated functions can have varying signatures in Django.
  • I believe this is the best practical balance between type safety and usability in this context.

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@UnknownPlatypus UnknownPlatypus Mar 29, 2026

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I believe this is the best practical balance between type safety and usability in this context.

Can you link to relevant django source code that make you conclude that ?


TZ_SUPPORT: bool

Expand Down Expand Up @@ -81,13 +79,16 @@ class modify_settings(override_settings):

class override_system_checks(TestContextDecorator):
registry: CheckRegistry
new_checks: list[Callable]
deployment_checks: list[Callable] | None
def __init__(self, new_checks: list[Callable], deployment_checks: list[Callable] | None = ...) -> None: ...
old_checks: set[Callable]
old_deployment_checks: set[Callable]
new_checks: list[Callable[..., Any]]
deployment_checks: list[Callable[..., Any]] | None
def __init__(
self, new_checks: list[Callable[..., Any]], deployment_checks: list[Callable[..., Any]] | None = ...
) -> None: ...
old_checks: set[Callable[..., Any]]
old_deployment_checks: set[Callable[..., Any]]

class CaptureQueriesContext(_SupportsContains[dict[str, str]]):
# Private API removed, iterable-based
class CaptureQueriesContext(Iterable[dict[str, str]]):
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@UnknownPlatypus UnknownPlatypus Mar 28, 2026

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Replaced _SupportsContains with Iterable in CaptureQueriesContext to make type-checking safer.

Is it correct tho? Can you verify at runtime that it really respect the Iterable protocol and adda test in tests/assert_type to demonstrate why this is needed ?

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@01-Harshit 01-Harshit Mar 28, 2026

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Thank you for the review and questions!

  • The change from _SupportsContains to Iterable was to remove private API and ensure public iterable protocol adherence for safer type checking.
  • I will add a test case in tests/assert_type.py to verify CaptureQueriesContext respects the iterable protocol at runtime.

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@UnknownPlatypus UnknownPlatypus Mar 29, 2026

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I will add a test case in tests/assert_type.py to verify CaptureQueriesContext respects the iterable protocol at runtime.

You did not add a test, pls don’t resolve a thread if you have not addressed the feedback

connection: BaseDatabaseWrapper
force_debug_cursor: bool
initial_queries: int
Expand All @@ -108,13 +109,13 @@ class CaptureQueriesContext(_SupportsContains[dict[str, str]]):

class ignore_warnings(TestContextDecorator):
ignore_kwargs: dict[str, Any]
filter_func: Callable
filter_func: Callable[..., Any]
def __init__(self, **kwargs: Any) -> None: ...
catch_warnings: AbstractContextManager[list | None]

requires_tz_support: Any

def isolate_lru_cache(lru_cache_object: Callable) -> AbstractContextManager[None]: ...
def isolate_lru_cache(lru_cache_object: Callable[..., Any]) -> AbstractContextManager[None]: ...

class override_script_prefix(TestContextDecorator):
prefix: str
Expand Down
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