It’s not cakewalk to become master in RegEx. One has to have a deep understanding of what value each meta-character retains which also demands a lot of practice. More tough it becomes to judge the level of understanding. I mean, one can write multiple regex to match a single text. A person who doesn’t only write regex that matches the given text but also pushes him to make it smart one which triggers least on unexpected text, so called False positives.
It’s time to test how high you stand when it comes to understanding of Regex.