test-data/unit/check-parameter-specification.test

[case testBasicParamSpec]
from typing_extensions import ParamSpec
P = ParamSpec('P')
[builtins fixtures/tuple.pyi]

[case testParamSpecLocations]
from typing import Callable, List
from typing_extensions import ParamSpec, Concatenate
P = ParamSpec('P')

x: P  # E: ParamSpec "P" is unbound

def foo1(x: Callable[P, int]) -> Callable[P, str]:  ...

def foo2(x: P) -> P: ...  # E: Invalid location for ParamSpec "P" \
                          # N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'

# TODO(PEP612): uncomment once we have support for Concatenate
# def foo3(x: Concatenate[int, P]) -> int: ...  $ E: Invalid location for Concatenate

def foo4(x: List[P]) -> None: ...  # E: Invalid location for ParamSpec "P" \
                                   # N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'

def foo5(x: Callable[[int, str], P]) -> None: ...  # E: Invalid location for ParamSpec "P" \
                                                   # N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'

def foo6(x: Callable[[P], int]) -> None: ...  # E: Invalid location for ParamSpec "P" \
                                              # N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'
[builtins fixtures/tuple.pyi]

[case testParamSpecTemporaryAnyBehaviour]
# TODO(PEP612): behaviour tested here should change
# This is a test of mypy's temporary behaviour in lieu of full support for ParamSpec
from typing import Callable, List, Iterator, TypeVar
from typing_extensions import ParamSpec
P = ParamSpec('P')
T = TypeVar('T')

def changes_return_type_to_str(x: Callable[P, int]) -> Callable[P, str]: ...

def returns_int(a: str, b: bool) -> int: ...

reveal_type(changes_return_type_to_str(returns_int))  # N: Revealed type is "def (*Any, **Any) -> builtins.str"

def tmpcontextmanagerlike(x: Callable[P, Iterator[T]]) -> Callable[P, List[T]]: ...

@tmpcontextmanagerlike
def whatever(x: int) -> Iterator[int]:
    yield x

reveal_type(whatever)  # N: Revealed type is "def (*Any, **Any) -> builtins.list[builtins.int*]"
reveal_type(whatever(217))  # N: Revealed type is "builtins.list[builtins.int*]"
[builtins fixtures/tuple.pyi]

[case testGenericParamSpecTemporaryBehaviour]
# flags: --python-version 3.10
# TODO(PEP612): behaviour tested here should change
from typing import Generic, TypeVar, Callable, ParamSpec

T = TypeVar("T")
P = ParamSpec("P")

class X(Generic[T, P]):  # E: Free type variable expected in Generic[...]
  f: Callable[P, int]  # E: The first argument to Callable must be a list of types or "..."
  x: T
[out]

[case testInvalidParamSpecType]
# flags: --python-version 3.10
from typing import ParamSpec

P = ParamSpec("P")

class MyFunction(P):  # E: Invalid location for ParamSpec "P" \
                      # N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'
    ...

a: MyFunction[int]  # E: "MyFunction" expects no type arguments, but 1 given