generics_paramspec_basic.py

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TP: 2

FP: 0

FN: 5

Optional: 0 / 0

"""
Tests basic usage of ParamSpec.
"""

# Specification: https://typing.readthedocs.io/en/latest/spec/generics.html#paramspec-variables

from typing import Any, Callable, Concatenate, ParamSpec, TypeAlias

P = ParamSpec("P")  # OK
WrongName = ParamSpec("NotIt")  # E: name inconsistency
[invalid-paramspec] The name of a `ParamSpec` (`NotIt`) must match the name of the variable it is assigned to (`WrongName`)


# > Valid use locations

TA1: TypeAlias = P  # E
Expected a ty diagnostic for this line

TA2: TypeAlias = Callable[P, None]  # OK
TA3: TypeAlias = Callable[Concatenate[int, P], None]  # OK
TA4: TypeAlias = Callable[..., None]  # OK
TA5: TypeAlias = Callable[..., None]  # OK


def func1(x: P) -> P:  # E
[empty-body] Function always implicitly returns `None`, which is not assignable to return type `P@func1`
    ...


def func2(x: Concatenate[int, P]) -> int:  # E
Expected a ty diagnostic for this line
    raise NotImplementedError


def func3(x: list[P]) -> None:  # E
Expected a ty diagnostic for this line
    ...


def func4(x: Callable[[int, str], P]) -> None:  # E
Expected a ty diagnostic for this line
    ...


def func5(*args: P, **kwargs: P) -> None:  # E
Expected a ty diagnostic for this line
    ...