def test_default_value_ellipsis():
    """
    https://github.com/pydantic/pydantic/issues/5488
    """

    @pydantic.dataclasses.dataclass
    class MyDataclass:
        v: int = ...

    assert dataclasses.asdict(MyDataclass(v=42)) == {'v': 42}
    with pytest.raises(ValidationError, match='type=missing'):
        MyDataclass()

    https://github.com/pydantic/pydantic/issues/5488
    
tests/test_dataclasses.py