gistfile1

# This function replaces any portion of a string and returns an identically
# sized string. How might the sanity tests at the top fail to return an
# identical sized string.
#
# Where else is it broken?
#
# How would you test it?

def slice_and_transform(str, loc, len, rep)
  if (loc < 1)
    return nil
  end

  if (loc + len > str.length)
    return nil
  end

  str.slice!(loc, len)
  return str + rep
end

str = "Hello Earth"
loc = 6
rep = "Venus"

puts(slice_and_transform(str, loc, rep.length, rep))