st.from_type doesn't work for type alias (typing.TypeAliasType)

[ilkecan]

Given a type alias (which is of type TypeAliasType) defined like:

>>> type Point = tuple[float, float]
>>> type(Point)
<class 'typing.TypeAliasType'>

I want to create a strategy and an example from that:

from hypothesis import strategies as st
st.from_type(Point).example()

which results in an error

...
.venv/lib/python3.13/site-packages/hypothesis/strategies/_internal/core.py", line 1287, in _from_type
    raise InvalidArgument(f"{thing=} must be a type")  # pragma: no cover
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
hypothesis.errors.InvalidArgument: thing=Point must be a type

Accessing the underlying value through __value__ works as expected:

>>> st.from_type(Point.__value__).example()
(1.192092896e-07, -7420061444470370.0)

I am not familiar with the internals of hypothesis but since Point.__value__ works, I am inclined to think Point should also just work by handling typing.TypeAliasType internally.

python version: Python 3.13.1 (main, Dec 3 2024, 17:59:52) [GCC 14.2.1 20241116] on linux
hypothesis version: 6.123.17

[Zac-HD]

That makes sense to me - we could handle it just below NewType, and in much the same way. Tests would go in a new tests/cover/test_typealias_py312.py file, and add this config for 3.12 so it doesn't give SyntaxError on older versions.

Would you be interested in opening a PR?