fails:String#unpack with format 'X' ignores whitespace in the format string
fails:String#unpack with format 'X' calls #to_str to coerce the directives string
fails:String#unpack with format 'X' raises a TypeError when passed nil
fails:String#unpack with format 'X' raises a TypeError when passed an Integer
fails:String#unpack with format 'X' raises an ArgumentError when the format modifier is '_'
fails:String#unpack with format 'X' raises an ArgumentError when the format modifier is '!'
fails:String#unpack with format 'X' moves the read index back by the number of bytes specified by count
fails:String#unpack with format 'X' does not change the read index when passed a count of zero
fails:String#unpack with format 'X' implicitly has a count of one when count is not specified
fails:String#unpack with format 'X' moves the read index back by the remaining bytes when passed the '*' modifier
fails:String#unpack with format 'X' raises an ArgumentError when passed the '*' modifier if the remaining bytes exceed the bytes from the index to the start of the String
fails:String#unpack with format 'X' raises an ArgumentError if the count exceeds the bytes from current index to the start of the String
fails:String#unpack with format 'x' ignores whitespace in the format string
fails:String#unpack with format 'x' calls #to_str to coerce the directives string
fails:String#unpack with format 'x' raises a TypeError when passed nil
fails:String#unpack with format 'x' raises a TypeError when passed an Integer
fails:String#unpack with format 'x' raises an ArgumentError when the format modifier is '_'
fails:String#unpack with format 'x' raises an ArgumentError when the format modifier is '!'
fails:String#unpack with format 'x' moves the read index forward by the number of bytes specified by count
fails:String#unpack with format 'x' implicitly has a count of one when count is not specified
fails:String#unpack with format 'x' does not change the read index when passed a count of zero
fails:String#unpack with format 'x' moves the read index to the end of the string when passed the '*' modifier
fails:String#unpack with format 'x' positions the read index one beyond the last readable byte in the String
fails:String#unpack with format 'x' raises an ArgumentError if the count exceeds the size of the String
