add first test for prime factors of 1.
add the requirement that the argument to PrimeFactor needs to be larger
than 0.
add test and production code to 2.
add test and production code for 3.
add test and production code for 4. This requires us to implement an
iterative process with recursion.
Add ineffective test cases of 6 and 8. Test on 9 failed.
fixed the test case 9 but failed for case 3 and 6.
fixed all the test cases, now we can see the obvious duplication.
extract the general case into a local recursive function as "loop".
the extracted loop function works, now there are more duplications.
removed duplications, passed all the tests.
add one more test case 24. Since the problem and solution have a very
nice and easily verifiable mathematical property. How about using
ScalaCheck for this purpose?
Merge branch 'PrimeFactors'