How to find out if string has already been URL encoded?

Question

How could I check if string has already been encoded?

For example, if I encode TEST==, I get TEST%3D%3D. If I again encode last string, I

Answer 1

In order to avoid encoding twice and generating a bug (as the OP is stating) we unquote and than quote again, in Python this will be:

import urllib.parse
urllib.parse.unquote(str)
urllib.parse.quote(str)