"""

Tests the handling of descriptors within a dataclass.

"""

# This portion of the dataclass spec is under-specified in the documentation,

# but its behavior can be determined from the runtime implementation.

from dataclasses import dataclass

from typing import Any, Generic, TypeVar, assert_type, overload

T = TypeVar("T")

class Desc1:

@overload

def __get__(self, __obj: None, __owner: Any) -> "Desc1":

...

@overload

def __get__(self, __obj: object, __owner: Any) -> int:

...

def __get__(self, __obj: object | None, __owner: Any) -> "int | Desc1":

raise NotImplementedError

def __set__(self, __obj: object, __value: int) -> None:

...

@dataclass

class DC1:

y: Desc1 = Desc1()

dc1 = DC1(3)

assert_type(dc1.y, int)

assert_type(DC1.y, Desc1)

class Desc2(Generic[T]):

@overload

def __get__(self, instance: None, owner: Any) -> list[T]:

...

@overload

def __get__(self, instance: object, owner: Any) -> T:

...

def __get__(self, instance: object | None, owner: Any) -> list[T] | T:

raise NotImplementedError

@dataclass

class DC2:

x: Desc2[int]

y: Desc2[str]

z: Desc2[str] = Desc2()

assert_type(DC2.x, list[int])

assert_type(DC2.y, list[str])

assert_type(DC2.z, list[str])

dc2 = DC2(Desc2(), Desc2(), Desc2())

assert_type(dc2.x, int)

assert_type(dc2.y, str)

assert_type(dc2.z, str)