"""Tests for CustomSlice in src/type_aliases.py

Per-aggregate dataclass regression-guard for the metadata_promotion_20260624 track.

CONVENTION: 1-space indentation. NO COMMENTS.
"""
from __future__ import annotations

from dataclasses import FrozenInstanceError

import pytest

from src.type_aliases import CustomSlice


def test_constructor_with_kwargs() -> None:
 cs = CustomSlice(tag="hotspot", comment="key section", start_line=10, end_line=20)
 assert cs.tag == "hotspot"
 assert cs.comment == "key section"
 assert cs.start_line == 10
 assert cs.end_line == 20


def test_field_access() -> None:
 cs = CustomSlice(tag="x", start_line=5)
 assert cs.tag == "x"
 assert cs.start_line == 5


def test_frozen_raises_on_mutation() -> None:
 cs = CustomSlice()
 with pytest.raises(FrozenInstanceError):
  cs.tag = "x"


def test_to_dict_roundtrip() -> None:
 cs = CustomSlice(tag="t", comment="c", start_line=1, end_line=5)
 d = cs.to_dict()
 assert d["tag"] == "t"
 assert d["comment"] == "c"
 assert d["start_line"] == 1
 assert d["end_line"] == 5


def test_default_values() -> None:
 cs = CustomSlice()
 assert cs.tag == ""
 assert cs.comment == ""
 assert cs.start_line == 0
 assert cs.end_line == 0


def test_hashability() -> None:
 cs = CustomSlice(tag="t")
 assert hash(cs) is not None