Perhaps the kata could be made more interesting by requiring the class to be an enum, with members GAS, LIQUID, SOLID and a method (or an immutable final Map) that returns the correct transition name. There are relatively few kata that involve enums on Codewars.

There are no reasons to run 1500000 tests unless you want to exhaust all possibilities of hh:mm-hh:mm, but that's very stupid. Unless it's for performance reasons, but why performance requirement in such a trivial kata? It's kinda of delving into micro-optimization category.

There are 1500000 random tests, so the solution should not be slow.

Random tests are making double the amount of calls.

More worryingly, this happens because random tests are calling the user function twice and asserting the two results are equal, which means random tests are not working at all.

import java.util.Date is missing in the initial code.

Neat!

Nice solution!
You actually don't need the ternary conditional operator, because the default value of a boolean in Java is false.

Now it is working without the commented line. Thank you!

Could you please check again?

I mean the code which is correct but does not pass tests.

Can you post the code which errors out?

In kotlin version: Incorrect answer for disks=64 expected:<0> but was:<18446744073709551615>

Please review the kotlin translation.

Parenthesis are unnecessary since && has higher precedence than ||