Fix mypy issue with async resolvers

RELEASE.md

@@ -0,0 +1,7 @@
+Release type: patch
+
+This release fixes an issue where mypy would complain when using a typed async
+resolver with `strawberry.field(resolver=...)`.
+
+Now the code will type check correctly. We also updated our test suite to make
+we catch similar issues in the future.

TWEET.md

@@ -0,0 +1,6 @@
+🆕 Release $version is out! This release fixes an issue that caused type
+checking errors when using Mypy and async resolvers.
+
+Thanks to $contributor for the PR 👏
+
+Get it here 👉 $release_url

noxfile.py

@@ -15,8 +15,7 @@
     "auto",
     "--showlocals",
     "-vv",
-    "--ignore=tests/mypy",
-    "--ignore=tests/pyright",
+    "--ignore=tests/typecheckers",
     "--ignore=tests/cli",
     "--ignore=tests/benchmarks",
     "--ignore=tests/experimental/pydantic",
@@ -125,42 +124,24 @@ def test_pydantic(session: Session, pydantic: str) -> None:
     )
 
 
-@session(python=PYTHON_VERSIONS, name="Mypy tests")
-def tests_mypy(session: Session) -> None:
-    session.run_always("poetry", "install", "--with", "integrations", external=True)
-
-    session.run(
-        "pytest",
-        "--cov=.",
-        "--cov-append",
-        "--cov-report=xml",
-        "tests/mypy",
-        "-vv",
-    )
-
-
-@session(python=PYTHON_VERSIONS, name="Pyright tests", tags=["tests"])
-def tests_pyright(session: Session) -> None:
+@session(python=PYTHON_VERSIONS, name="Type checkers tests", tags=["tests"])
+def tests_typecheckers(session: Session) -> None:
     session.run_always("poetry", "install", external=True)
+
     session.install("pyright")
+    session.install("pydantic")
+    session.install("git+https://github.com/python/mypy.git#master")
 
     session.run(
         "pytest",
         "--cov=.",
         "--cov-append",
         "--cov-report=xml",
-        "tests/pyright",
+        "tests/typecheckers",
         "-vv",
     )
 
 
-@session(name="Mypy", tags=["lint"])
-def mypy(session: Session) -> None:
-    session.run_always("poetry", "install", "--with", "integrations", external=True)
-
-    session.run("mypy", "--config-file", "mypy.ini")
-
-
 @session(python=PYTHON_VERSIONS, name="CLI tests", tags=["tests"])
 def tests_cli(session: Session) -> None:
     session.run_always("poetry", "install", external=True)
@@ -176,3 +157,11 @@ def tests_cli(session: Session) -> None:
         "tests/cli",
         "-vv",
     )
+
+
+@session(name="Mypy", tags=["lint"])
+def mypy(session: Session) -> None:
+    session.run_always("poetry", "install", "--with", "integrations", external=True)
+    session.install("mypy")
+
+    session.run("mypy", "--config-file", "mypy.ini")

pyproject.toml

@@ -98,12 +98,11 @@ types-toml = "^0.10.8"
 types-typed-ast = "^1.5.8"
 types-ujson = "^5.6.0"
 types-protobuf = "^4.23.0.1"
-mypy = "1.9.0"
-pytest-mypy-plugins = "3.0.0"
 poetry-plugin-export = "^1.6.0"
 # another bug in poetry
 urllib3 = "<2"
 graphlib_backport = {version = "*", python = "<3.9", optional = false}
+inline-snapshot = "^0.10.1"
 
 [tool.poetry.group.integrations]
 optional = true
@@ -149,7 +148,7 @@ pyinstrument = ["pyinstrument"]
 strawberry = "strawberry.cli:run"
 
 [tool.pytest.ini_options]
-addopts = "--emoji --mypy-ini-file=mypy.ini"
+addopts = "--emoji"
 DJANGO_SETTINGS_MODULE = "tests.django.django_settings"
 testpaths = ["tests/"]
 markers = [

strawberry/extensions/base_extension.py

@@ -24,27 +24,27 @@ class SchemaExtension:
     def __init__(self, *, execution_context: ExecutionContext) -> None:
         self.execution_context = execution_context
 
-    def on_operation(
+    def on_operation(  # type: ignore
         self,
-    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover # pyright: ignore
+    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover
         """Called before and after a GraphQL operation (query / mutation) starts"""
         yield None
 
-    def on_validate(
+    def on_validate(  # type: ignore
         self,
-    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover # pyright: ignore
+    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover
         """Called before and after the validation step"""
         yield None
 
-    def on_parse(
+    def on_parse(  # type: ignore
         self,
-    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover # pyright: ignore
+    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover
         """Called before and after the parsing step"""
         yield None
 
-    def on_execute(
+    def on_execute(  # type: ignore
         self,
-    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover # pyright: ignore
+    ) -> AsyncIteratorOrIterator[None]:  # pragma: no cover
         """Called before and after the execution step"""
         yield None
 

strawberry/field.py

@@ -46,15 +46,20 @@
 
 T = TypeVar("T")
 
-_RESOLVER_TYPE = Union[
+_RESOLVER_TYPE_SYNC = Union[
     StrawberryResolver[T],
     Callable[..., T],
-    Callable[..., Coroutine[Any, Any, T]],
-    Callable[..., Awaitable[T]],
     "staticmethod[Any, T]",
     "classmethod[Any, Any, T]",
 ]
 
+_RESOLVER_TYPE_ASYNC = Union[
+    Callable[..., Coroutine[Any, Any, T]],
+    Callable[..., Awaitable[T]],
+]
+
+_RESOLVER_TYPE = Union[_RESOLVER_TYPE_SYNC[T], _RESOLVER_TYPE_ASYNC[T]]
+
 UNRESOLVED = object()
 
 
@@ -416,10 +421,33 @@ def is_async(self) -> bool:
         return self._has_async_base_resolver
 
 
+# NOTE: we are separating the sync and async resolvers because using both
+# in the same function will cause mypy to raise an error. Not sure if it is a bug
+
+
+@overload
+def field(
+    *,
+    resolver: _RESOLVER_TYPE_ASYNC[T],
+    name: Optional[str] = None,
+    is_subscription: bool = False,
+    description: Optional[str] = None,
+    init: Literal[False] = False,
+    permission_classes: Optional[List[Type[BasePermission]]] = None,
+    deprecation_reason: Optional[str] = None,
+    default: Any = dataclasses.MISSING,
+    default_factory: Union[Callable[..., object], object] = dataclasses.MISSING,
+    metadata: Optional[Mapping[Any, Any]] = None,
+    directives: Optional[Sequence[object]] = (),
+    extensions: Optional[List[FieldExtension]] = None,
+    graphql_type: Optional[Any] = None,
+) -> T: ...
+
+
 @overload
 def field(
     *,
-    resolver: _RESOLVER_TYPE[T],
+    resolver: _RESOLVER_TYPE_SYNC[T],
     name: Optional[str] = None,
     is_subscription: bool = False,
     description: Optional[str] = None,
@@ -455,7 +483,25 @@ def field(
 
 @overload
 def field(
-    resolver: _RESOLVER_TYPE[T],
+    resolver: _RESOLVER_TYPE_ASYNC[T],
+    *,
+    name: Optional[str] = None,
+    is_subscription: bool = False,
+    description: Optional[str] = None,
+    permission_classes: Optional[List[Type[BasePermission]]] = None,
+    deprecation_reason: Optional[str] = None,
+    default: Any = dataclasses.MISSING,
+    default_factory: Union[Callable[..., object], object] = dataclasses.MISSING,
+    metadata: Optional[Mapping[Any, Any]] = None,
+    directives: Optional[Sequence[object]] = (),
+    extensions: Optional[List[FieldExtension]] = None,
+    graphql_type: Optional[Any] = None,
+) -> StrawberryField: ...
+
+
+@overload
+def field(
+    resolver: _RESOLVER_TYPE_SYNC[T],
     *,
     name: Optional[str] = None,
     is_subscription: bool = False,