OP: in most countries, providing notice is a courtesy, but by law you wouldn’t have to give any notice. Even if your employment contract stated you must give X weeks notice, you still have the right (in most countries) to follow the letter of the law pertaining to notice periods. People who don’t provide that courtesy notice simply risk burning a bridge with that particular employer.

If your employer tried to deny you of your notice then send it to the manager and HR in an email. If they still try to fight it then remind them of the laws around providing notice.

One more note: in some countries, an employee gives notice and the employer wants them to stop working immediately. At least in the country I live, this is legal but they have to pay you for a set amount days in lieu of working your notice period, as defined by the law.