Kata

most likely, that's your solution that doesn't handle properly some edge case. When you raise this kind of issue, you should extract the actual input that is causing this, so that it can be sorted out if the problem is:

• your code
• the code of the ref solution
• insufficient test coverage

=> ?

one moment, please

ok, got it: sometimes random tests have empty strings (my solution failed with it). So it's better to add this:

 assertEquals("", JomoPipi.antiString(""));

done, thanks!