link_checker.rb

require 'em-http'

module LinkChecker
  class LinkChecker
    include EM::Deferrable

    def initialize(url)
      resp =  Net::HTTP.get_response(url_address)
      @status_code = resp.code.to_i

      request = EM::HttpRequest.new(url, connect_timeout: 5, inactivity_timeout: 10)

      request.callback {
        ...

        succeed({status_code: @status_code, Time.now})
      }

      request.errback {
        fail({reason: request.error, Time.now})
      }

      self
    end

  end
end

link_checker_spec.rb

require 'spec_helper'
 
describe LinkChecker do
  it "calls back" do
    LinkChecker.new('http://www.google.com').should_receive.success
  end
end