Regex Pattern recursion famous test solution

It has become very common and thus having a test without a solution for me as I badly blundered because of these test for a specific candidature make me think that it may has become very interesting to keep solution somewhere on my website.

This is the acceptation tests :

using NUnit.Framework;

namespace maximilien.zakowski.Tests
{
    public class Tests
    {
        private Library BuildTested()
        {
            return new ParenthesesBracketsPatternTester();
        }

        [TestCase("()")]
        [TestCase("[]")]
        [TestCase("[()]")]
        [TestCase("[[()]]")]
        [TestCase("[()[]]")]
        [TestCase("([()[]])")]
        public void Test1(string validated)
        {
            var tested = BuildTested();
            Assert.IsTrue(tested.IsValid(validated));
        }
    }
}

The solution to this problems is the regex Pattern recursion :

Source : https://www.regular-expressions.info/refrecurse.html

The solution underneath :

using System.Text.RegularExpressions;

namespace maximilien.zakowski
{
    public class ParenthesesBracketsPatternTester
    {
        public bool IsValid(string validated)
        {
            var regex = new Regex("(?'group'(\\(\\)|\\[\\]))((?'group')|(\\((?'group')\\))|(\\[(?'group')\\]))");
            return regex.IsMatch(validated);
        }
    }
}