def test_supports_stdlib_dataclass_without_annotations() -> None:
    """https://github.com/pydantic/pydantic/issues/2594"""

    @dataclasses.dataclass
    class Empty:
        pass

    @pydantic.dataclasses.dataclass
    class M:
        e: Empty

    assert isinstance(M(e={}).e, Empty)
https://github.com/pydantic/pydantic/issues/2594
tests/test_dataclasses.py