Duplicate.

Before writing "production" code lots of good programmers find handy to write "debug" code as long as their code isn't right and the code is not right as long as it doesn't pass the tests. Furthermore they write their own tests (maybe it is less convenient because it demands a bit of an effort but it is a good and necessary practice); many katas don't even give any "Your example test cases". Thanks for your feedback!

Why don't you (or anyone else) print inputs? You will have every clue you need!

Which language?

There are more than 100 tests... I think it is enough, no? What do you mean by better description of tests? Moreover this kata is quite easy.