Exactly that is what I was thinking when I checked for the tests and I haven't seen anything in regards to that. If they really want to get the real deal, they

Exactly that is what I was thinking when I checked for the tests and I haven't seen anything in regards to that. If they really want to get the real deal, they would have to support that too. However as others already pointed out, it's better not to use a regex for it, but a proper library for your language which would bail out as soon as it hits something invalid. With the hope that the library for the language does support that already.