问题 1 :

class  < Action::Base
    def current_user
       ...
    end
end

class Home < 
   def index
      current_user # 为什么 的方法还能在Home里面用？
   end
end

问题 2:

require "spec_helper"

class  < Action::Base
  protect_from_forgery

  def current_user
    session[:user_id]
  end
end

describe ApplicationController do
  describe "current_user" do
    it "should return nil if no one is logged in" do
      subject.current_user.should be_nil
    end
    it "should return currently logged in user" do
      hash = {user_id: "my_id"}
      subject.should_receive(:session).and_return hash
      subject.current_user.should == "my_id"
    end
  end
end

NoMethodError:: `current_user' called for #<? 为什么会在测试中找不到实例方法？