I think this is an accidental kata. Otherwise, please make a description more informative.

The description should clearly state that it is supposed to generate the random code. Also, the tests do not check for digits presence and can be passed without bothering with them. Probably the same with letters...

[11,17,28,9,0,23] average is 14.(6) and should be rounded to 15, not 14

The sample tests' method name is wrongly spelled and should be corrected

The simplest solutions do not pass due to "warning: constant ::Fixnum is deprecated", please fix this

I got "warning: constant ::Fixnum is deprecated" when using MRI 2.5.0, had to switch to 2.3.0 to pass, please improve

I am unable to pass 7th and 8th test in "should return NaN for non-integer strings" (ruby). What's in them?

Since this is a beginner level, some sample tests would be more than helpful.

I enjoyed this kata a lot!

There is a problem with random tests in ruby. If adjacent digits are the same e.g. 77, the number is supposed to be a jumping one. While descroption says "All adjacent digits in it differ by 1.". And 7 and 7 do not differ by 1.

I really do not know why my code does not pass the test and what I am supposed to do (ruby).

I cannot understand why the kata doesn't pass the tests with a solution based on "<< 1" in ruby.