class SyntaxTree::CLI::Debug

format is not idempotent.
An action of the CLI that formats the source twice to check if the first

def failure 

def failure
  warn("The listed files could not be formatted idempotently.")
end

def run(item) 

def run(item)
  handler = item.handler
  warning = "[#{Color.yellow("warn")}] #{item.filepath}"
  formatted =
    handler.format(
      item.source,
      options.print_width,
      options: options.formatter_options
    )
  double_formatted =
    handler.format(
      formatted,
      options.print_width,
      options: options.formatter_options
    )
  raise NonIdempotentFormatError if formatted != double_formatted
rescue StandardError
  warn(warning)
  raise
end

def success 

def success
  puts("All files can be formatted idempotently.")
end