def test_resolve_region_code():
    from app.services.ip_service import resolve_region_code
    # 公网IP返回 ISO alpha-2 或 None(查不到),绝不返回中文/"本地"/"未知"
    r = resolve_region_code("104.28.41.169")
    assert r is None or (isinstance(r, str) and len(r) == 2 and r.isupper() and r.isalpha())
    assert resolve_region_code("") is None
    assert resolve_region_code("127.0.0.1") is None
    assert resolve_region_code("::1") is None

def test_country_names_ca_bug_fixed():
    from app.services import ip_service
    assert ip_service.COUNTRY_NAMES.get("CA") == "加拿大"
    assert ip_service.COUNTRY_NAMES.get("AU") == "澳大利亚"


def test_resolve_region_code_known_ip_deterministic():
    from app.services.ip_service import resolve_region_code
    assert resolve_region_code("8.8.8.8") == "US"   # Google DNS, 离线库确定性