dateutil/dateutil#1478 の再現

import sys

import dateutil
from dateutil.parser import parse

STAMP = "2026-03-11 14:32:45"
CASES = [("UTC-4", -4), ("UTC+4", +4), ("UTC-04:00", -4), ("UTC+04:00", +4)]


def offset(seconds):
    sign = "-" if seconds < 0 else "+"
    return f"{sign}{abs(seconds) // 3600:02d}:{abs(seconds) % 3600 // 60:02d}"


results = []
for spec, expected_hours in CASES:
    expected = expected_hours * 3600
    actual = int(parse(f"{STAMP} {spec}").utcoffset().total_seconds())
    results.append(
        {
            "input": spec,
            "expected_offset_seconds": expected,
            "actual_offset_seconds": actual,
            "inverted": actual == -expected and actual != expected,
        }
    )

print(f"parse('{STAMP} <input>').utcoffset()")
print()
print(f"{'input':<12}{'expected':>10}{'actual':>10}")
for row in results:
    flag = "   <-- sign flipped" if row["inverted"] else ""
    print(
        f"{row['input']:<12}"
        f"{offset(row['expected_offset_seconds']):>10}"
        f"{offset(row['actual_offset_seconds']):>10}{flag}"
    )
print()
flipped = sum(row["inverted"] for row in results)
print(f"{flipped} of {len(results)} UTC-prefixed offsets came back negated.")
print(f"python-dateutil {dateutil.__version__} / Python {sys.version.split()[0]}")