I have just looked at tests in Go. They are weak and rather bad. I'll raise an issue about that. I mark your suggestion as solved since I will include it in a larger issue.

You cannot always edit a posted message afterward (When? This is still a mystery for me...).

I'm new to the format and don't see an edit suggestion button, so I'll answer in a reply. The language I was speaking of was Go.

What's weird is when one runs your code test after test, here too it works fine. But when running several tests on a row then the code crashes. I didn't examine your code in detail. Don't you have something like a global variable somewhere?

Please state the language. Some of them already do this.

These look like valid IPv4 test cases, in which case, there should be tests to see whether more than 4 octects were given e.g. 1.2.3.4.5