fails:Array#sample with options when the object returned by #rand is a Fixnum uses the fixnum as index
fails:Array#sample when the object returned by #rand is not a Fixnum but responds to #to_int calls #to_int on the Object
fails:Array#sample when the object returned by #rand is not a Fixnum but responds to #to_int raises a RangeError if the value is less than zero
fails:Array#sample when the object returned by #rand is not a Fixnum but responds to #to_int raises a RangeError if the value is equal to the Array size
