Good idea.  I actually came across an interesting scenario when passing in an integer like 028.  Ruby reads in integers with leading zeros as octal, so Ruby itself throws a SyntaxError on my spec test if I try to assign 028 to a variable.  I'm not sure how to stub that out or if it would even make sense to.  The integer tests would be unneeded if it's decided Puppet can always be relied upon to pass single value parameters as a string.