ruby-on-rails – Devise Test Helper – sign_in不工作

测试：

before :each do
    @user = FactoryGirl.create :user
    sign_in @user
  end

  describe "GET index" do
    it "assigns all subscribers as @subscribers" do
      subscriber = @user.subscribers.create! valid_attributes
      get :index
      assigns(:subscribers).should eq([subscriber])
    end
  end

执行：

def index
    @subscribers = current_user.subscribers.all    <------- ERROR

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @subscribers }
    end
  end

Error:
 NoMethodError:
       undefined method `subscribers' for nil:NilClass

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