The answer for that expression is 8. You're reading the logs wrong.

Could someone explain me please why is this test asking me to output 1 instead of -1?

-9136--96474=?733?

I handled the fact that the 1 cannot be part of the whole answer because it's already included on -9136. So nothing comes to mind rn.

It's the next bigger number, not the biggest number, and it's been asked and answered before (for instance GolivetsAndreu's post). Try reading the posts already here next time, sometimes they have already the answer you look for.

It's difficult to tell if these expected outputs are correct because you did not provide inputs. All we know from the log you pasted is expected answer, and actual (yours) answer. But without knowing the input, we cannot tell which is correct.

Except two of them.

• Message "1234568079 should equal 1234567908" seems to relate to fixed test with input value 1234567890, and
• message "59884848498355 should equal 59884848483559" seems to relate to fixed test with input value of 59884848459853

If I got test cases correctly, then indeed the next bigger number with the same digits as 1234567890 (input) is 1234567908 (as expected), and not 1234568079, as your solution apparently answered. The same thing applies to the second test, and I think it will be safe to assume the same for random tests.

Your solution has a bug, and your answers are not correct.

Print the input too, those are only your wrong answers and the expected ones. In the first case, the input value was 1234567890, your code returned 1234568079 which is greater than 1234567908.

If tests say your solution is wrong, how can you know it's correct?

I just retested my Python solution and encountered no broken case.

Potentially helpful FAQ: https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution