"""Tests for MMAUsageStats 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 MMAUsageStats


def test_constructor_with_kwargs() -> None:
 u = MMAUsageStats(model="gpt-4", input=100, output=200)
 assert u.model == "gpt-4"
 assert u.input == 100
 assert u.output == 200


def test_field_access() -> None:
 u = MMAUsageStats(model="claude-3")
 assert u.model == "claude-3"


def test_frozen_raises_on_mutation() -> None:
 u = MMAUsageStats()
 with pytest.raises(FrozenInstanceError):
  u.model = "x"


def test_to_dict_roundtrip() -> None:
 u = MMAUsageStats(model="m", input=10, output=20)
 d = u.to_dict()
 assert d["model"] == "m"
 assert d["input"] == 10
 assert d["output"] == 20


def test_default_values() -> None:
 u = MMAUsageStats()
 assert u.model == "unknown"
 assert u.input == 0
 assert u.output == 0


def test_hashability() -> None:
 u = MMAUsageStats(model="x")
 assert hash(u) is not None