Basic setup for the PrimeFactor class and its test.
Round #1: A failed test for prime factor of zero.
An easy fix.
Round #2: A failed test for prime factor of two.
Add a simple if statement to solve it.
Round #3: A failed test for prime factor of three.
Simple approach works, again.
Round #4: A failed test for prime factor of four.
Its harder to find a solution, this time.
It seems I can refactor the code to keep DRY.
The while loops can be transformed to for loops, for simplicity.
The if statement is unnecessary now.
Give a quite large number to prove its right.