fails:Array#pack with format 'x' ignores whitespace in the format string
fails:Array#pack with format 'x' calls #to_str to coerce the directives string
fails:Array#pack with format 'x' taints the output string if the format string is tainted
fails:Array#pack with format 'x' raises ArgumentError when the format modifier is '_'
fails:Array#pack with format 'x' raises ArgumentError when the format modifier is '!'
fails:Array#pack with format 'X' ignores whitespace in the format string
fails:Array#pack with format 'X' calls #to_str to coerce the directives string
fails:Array#pack with format 'X' taints the output string if the format string is tainted
fails:Array#pack with format 'X' raises ArgumentError when the format modifier is '_'
fails:Array#pack with format 'X' raises ArgumentError when the format modifier is '!'
fails:Array#pack with format 'X' raises an ArgumentError if the output string is empty
fails:Array#pack with format 'X' raises an ArgumentError if the count modifier is greater than the bytes in the string
