mysociety/alaveteli

module Usage
  def usage_message(message)
    puts ''
    puts message
    puts ''
    exit 0
  end

  def check_for_env_vars(env_vars, example)
    missing = []
    env_vars.each do |env_var|
      missing << env_var unless ENV[env_var]
    end
    unless missing.empty?
      usage = "Usage: This task requires #{env_vars.to_sentence} - missing #{missing.to_sentence}"
      usage += "\nExample: #{example}" if example
      usage_message usage
    end
  end
end