function assert(condition: unknown, message = "assertion failed"): void {
  if (!condition) throw new Error(message);
}

function assertEqual<T>(actual: T, expected: T, message = "values should be equal"): void {
  if (actual !== expected) throw new Error(`${message}: expected ${String(expected)}, got ${String(actual)}`);
}

import { isMailboxMessageRead, mailboxSyncState } from "../src/features/mail/mailboxDisplay";

assert(isMailboxMessageRead(["\\Seen"]), "standard IMAP Seen flag marks a message as read");
assert(isMailboxMessageRead(["answered", "SEEN"]), "flag matching is case-insensitive and accepts normalized flags");
assert(!isMailboxMessageRead(["\\Answered", "\\Flagged"]), "messages without Seen remain unread");
assert(!isMailboxMessageRead(undefined), "missing flags fail safely to unread");

assertEqual(mailboxSyncState({ fromCache: false, refreshing: false, indexedAt: null }), "live");
assertEqual(mailboxSyncState({ fromCache: true, refreshing: false, indexedAt: "2026-08-19T09:00:00Z" }), "cached");
assertEqual(mailboxSyncState({ fromCache: true, refreshing: true, indexedAt: "2026-08-19T09:00:00Z" }), "refreshing");
assertEqual(mailboxSyncState(null), null);