Defensive FileWriter in Ruby

defensive_file_writer.rb

class DefensiveFileWriter
  def write(path, contents)
    fail_if_empty_contents(contents)
    fail_if_file_exist(path)
    write_file(path, contents)
  end

  private
  def fail_if_empty_contents(contents)
    raise 'Nothing to write!' if empty_contents?(contents)
  end

  def empty_contents?(contents)
    contents.nil? || contents.empty?
  end

  def fail_if_file_exist(path)
    raise 'File already exists!' if file_exist?(path)
  end

  def file_exist?(path)
    File.exist?(path) && !File.zero?(path)
  end

  def write_file(path, contents)
    IO.write(path, contents)
  end
end