Signal is integer, may be from 0 to 100

This part of the description is misleading because there are no signal inputs involved in this katas; the program takes no inputs and generate some outputs. In fact it probably doesn't even need to be mentioned since this will not affect testing in any way (as tests have handled this already).

Shouldn't the register be a generator? The kata design as is is so different from the actual in-game behaviour that it can barely be called as such.

It's not mentioned that the resulting slice should be converted back to a decimal integer.

slice n digits at start and f digits from end

This statement means "take n first elements and last f elements" which is the opposite of what the task is.

Sample tests should explicitly import the test framework and solution.

As it was pointed out here, chai is not configured properly.

Don't change text color in the description in a way that makes it hard to read.