The classic FizzBuzz game but built using TDD principles, testing using x-unit

The idea of FizzBuzz is that any number can be submitted, the number is then checked on the following criteria:

• If the number is divisible by 3 then the code returns "Fizz"
• If it's divisible by 5 then it returns "Buzz"
• And if the number is divisible by 3 & 5 then it returns "FizzBuzz"
• Finally if the number isn't divisible by either 3 or 5 then we return the number as a string.

I built this appication using tests first following the principle of, failed test, passed test, refactor code, retest.