from datetime import datetime, timezone

from app.api.timeutil import isoformat_utc


def test_naive_datetime_is_stamped_utc():
    # SQLite/aiosqlite round-trips DateTime columns as naive even though every
    # value written is UTC (app.db.models.utcnow) — this is the exact shape
    # returned by the ORM after a read (B-35).
    naive = datetime(2026, 7, 27, 6, 56, 47, 489110)
    result = isoformat_utc(naive)
    assert result == "2026-07-27T06:56:47.489110+00:00"


def test_aware_datetime_is_left_unchanged():
    aware = datetime(2026, 7, 27, 6, 56, 47, tzinfo=timezone.utc)
    assert isoformat_utc(aware) == aware.isoformat()


def test_none_passes_through():
    assert isoformat_utc(None) is None