为什么不让rspec登录到您的测试系统，而不是stubbing current_user呢？您可以执行如下操作：

describe "Req #5 - login" do
    it 'loads the login page' do
      get '/login'
      expect(last_response.status).to eq(200)
    end

    it 'loads the user index after login' do
      user = User.create(:username => "Raptor", :password => "Raptor")
      params = {
        :username => "Raptor",
        :password => "Raptor"
      }
      post '/login', params
      follow_redirect!
      expect(last_response.body).to include("Home Page for: Raptor")
    end
  end

您可以像这样存根控制器的current_user方法：

let(:current_user) { User.create(...) }

before do
  allow(@controller).to receive(:current_user).and_return(current_user)
end