建立一个 Admin模型。 如果你是默认的Devise, 那就把下面的Admin都替换成 User. 

1. rails_helper中：

RSpec.configure do |config|
  
  # 增加这一行：
  config.include Devise::TestHelpers, :type => :controller
end

def admin_login
  sign_in Admin.create(email: 'admin@this.com', password: '88888888')
end
spec/rails_help

spec :

# -*- encoding : utf-8 -*-
require 'rails_helper'

describe SystemSettingsController do
  before do
    admin_login
  end 

  it 'should get index' do
    get :index
    response.should be_success
  end 
end