Instead of imaging what the input is, try printing it.

All tests work for me except one.
"Should handle upcoming big numbers expected:<1> but was:<2>"
If upcomming number is 1000000, then current number is 999999 and it's interesting number, why should i return 1 if it's better to return an interesting number than an almost interesting one.

If it is interesting, then it's not almost interesting, where is the ambiguity?

returns a 2 if the number is "interesting" (see below), a 1 if an interesting number occurs within the next two miles, or a 0 if the number is not interesting.

Follow that order.

All of those numbers are interesting.