Ruby: Print un-printable data string

If I have a variable, x, that will sometime be a normal printable string, and sometimes be some random hex data (including unprintable chars), how can I reliably print that will space padding? ex:

def prin开发者_C百科t(x)
  puts("%-15s" % x) 
end

x = "test"
print(x) 
x = Array.new(256) { rand(256) }.pack('c*')
print(x) 

---

def print(x)
  puts "%-15s" % [x.inspect]
end

And if you want to get rid of the "...":

puts "%-15s" % [x.inspect[1..-2]]