Fix _RESOLVER_TYPE for async functions

[bricker]

Description

Fixes generic type arguments for Coroutine in RESOLVER_TYPE. The given types are incorrect: It is Coroutine[YieldType, SendType, ReturnType].

This allows catching when the return type of an async resolver is incompatible with the field type. For example:

async def resolver_func() -> int:
  ...

# currently not caught by typechecker
field: str = strawberry.field(resolver=resolver_func)

With the change made in this PR, the above code will be caught by typecheckers.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Documentation

Issues Fixed or Closed by This PR

• Fixes strawberry.field does not type check properly for async resolvers, but strawberry.field() does #3071

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[botberry]

Thanks for adding the RELEASE.md file!

Here's a preview of the changelog:

---

This release improves type checking for async resolver functions when used as
strawberry.field(resolver=resolver_func).

Now doing this will raise a type error:

import strawberry


def some_resolver() -> int:
    return 0


@strawberry.type
class User:
    # Note the field being typed as str instead of int
    name: str = strawberry.field(resolver=some_resolver)

Here's the tweet text:

🆕 Release (next) is out! Thanks to Bryan Ricker for the PR 👏

Get it here 👉 https://strawberry.rocks/release/(next)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.53%. Comparing base (014c4ec) to head (ffdc22d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3241   +/-   ##
=======================================
  Coverage   96.52%   96.53%           
=======================================
  Files         520      520           
  Lines       33243    33243           
  Branches     5527     5527           
=======================================
+ Hits        32089    32090    +1     
+ Misses        921      920    -1     
  Partials      233      233           

[codspeed-hq]

CodSpeed Performance Report

Merging #3241 will not alter performance

_{Comparing bricker:bcr/2311/fix-coroutine-fields (ffdc22d) with main (014c4ec)}

Summary

✅ 12 untouched benchmarks

[bricker]

I am converting this to Draft while I investigate the test failures. I need help from the maintainers to understand these failures.

For the record: This change does fix the errors from Pyright (via Pylance in VSCode), but the test failures are from mypy.

[DoctorJohn]

Unfortunately, according to Github, "the logs for this run have expired and are no longer available". This also hides the "re-run jobs" button for me. Could you try to mark this PR as ready for review? Hopefully this will trigger CI again and I can take a look. Edit: looks like marking the PR as ready for review didn't help. Need to figure out how to trigger CI again

[sourcery-ai]

Failed to review pull request #3241 due to the following error:

<class 'KeyError'>: 0

Try re-running the review or contact support@sourcery.ai for help.

[patrick91]

Sorry for the late review and merge! Looks great 😊

I've added a test for pyright, just to check the behaviour there 😊 (The error is weird, but at least it errors correctly :D)

[Ansud]

Dynamic field creation failed (or may be i doing something wrong).

Suppose you have code

def create_get_data_format_query(obj: SomeClass) -> tuple[str, Any, Field[DataSchema]]:
    async def resolver_func() -> DataSchema:
        db = session_context.get()

        s = await SomeClass.load_from_database(db, obj.id)

        if s is None:
            raise ValueError

        return await serialize_schema(s) # This function return DataSchema and typing is ok

    resolver: StrawberryField = strawberry.field(
        resolver=resolver_func,
        name="get_schema", description="Get schema",
    )

    return "get_schema", DataSchema, field(default=resolver)

And this produce following error

error: Argument "resolver" to "field" has incompatible type "Callable[[], Coroutine[Any, Any, DataSchema]]"; expected
"StrawberryResolver[Never] | Callable[..., Never] | Callable[..., Coroutine[Any, Any, Never]] | Callable[..., Awaitable[Never]] | staticmethod[Any, Never] | classmethod[Any, Any, Never]"  [arg-type]
            resolver=resolver_func,

Why DataSchema become Never? What do i do wrong or what do typing do wrong?

I tried to change StrawberryField to DataSchema - it not hepled.

[patrick91]

@Ansud it's not your fault, apparently this PR triggered a Mypy error, there's an initial fix here: #3516