directives_assert_type.py

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"""
Tests the typing.assert_type function.
"""

# Specification: https://typing.readthedocs.io/en/latest/spec/directives.html#assert-type

from typing import Annotated, Any, Literal, assert_type


# > When a type checker encounters a call to assert_type(), it should
# > emit an error if the value is not of the specified type.


def func1(
    a: int | str,
    b: list[int],
    c: Any,
    d: "ForwardReference",
    e: Annotated[Literal[4], ""],
):
    assert_type(a, int | str)  # OK
    assert_type(b, list[int])  # OK
    assert_type(c, Any)  # OK
    assert_type(d, "ForwardReference")  # OK
    assert_type(e, Literal[4])  # OK

    assert_type(a, int)  # E: Type mismatch
[type-assertion-failure] Type `int` does not match asserted type `int | str`
    assert_type(a, Any)  # E: Type mismatch
[type-assertion-failure] Type `Any` does not match asserted type `int | str`
    assert_type(c, int)  # E: Type mismatch
[type-assertion-failure] Type `int` does not match asserted type `Any`
    assert_type(e, int)  # E: Type mismatch
[type-assertion-failure] Type `int` does not match asserted type `Literal[4]`

    assert_type()  # E: not enough arguments
[missing-argument] No arguments provided for required parameters `value`, `type` of function `assert_type`
    assert_type("", int)  # E: wrong argument type
[type-assertion-failure] Type `int` does not match asserted type `Literal[""]`
    assert_type(a, int | str, a)  # E: too many arguments
[too-many-positional-arguments] Too many positional arguments to function `assert_type`: expected 2, got 3


# > If the two types are :term:`equivalent` but syntactically different,
# > the type checker may reject the ``assert_type()`` call::

def func2(name: str):
    assert_type(name, str | Literal["spam"])  # E?: Equivalent but not identical


class ForwardReference:
    pass