Missing fixed test where number = 0.

Also, it should be specified that 2 <= base <= 10. Any base bigger than 10 will require different things to be done.

Loop test is laguhably easy to bypass: https://www.codewars.com/kata/reviews/6431947bc58df4000189e1ef/groups/6431999f0b4bd1000162dfad

• loop test should use test.expect (with message), not assert
• input number is not in base 10, it is an integer
• no random tests
• this should not pass