Rails 4-控制器测试错误，活动记录关联问题

我将在问题下方发布所有文件。我对测试非常陌生。我正在尝试为我的应用编写控制器测试。模型是所有权。所有权归团队所有。我正在使用回形针宝石将徽标附加到每个团队。

运行测试时，出现以下错误：

 1) Error:
 OwnershipsControllerTest#test_Should_retrieve_results:
 ActionView::Template::Error: undefined method `logo_file_name' for  nil:NilClass
 app/views/ownerships/round1.html.erb:23:in `block in _app_views_ownerships_round__html_erb___2932533286089946925_70246915278440'
app/views/ownerships/round1.html.erb:18:in `each'
app/views/ownerships/round1.html.erb:18:in `_app_views_ownerships_round__html_erb___2932533286089946925_70246915278440'
test/controllers/ownership_controller_test.rb:12:in `block in <class:OwnershipsControllerTest>' 

它抱怨我如何处理视图中丢失的徽标。这是round1.html.erb中不喜欢的部分：

    <% if ownership.team.logo_file_name == nil %>
    <td></td>
    <% else %>  
        <td><%= image_tag ownership.team.logo.url(:medium) %></td>
    <% end %>

问题不在于回形针附件本身。对Team模型的任何引用都会引发错误。如果删除与徽标相关的代码，则以下内容也会产生相同的错误：

<％= owner.team.name％>

真正令人困惑的是，我对index方法的测试没有引发错误。index和round1视图的代码是相同的！如何设置测试，以便识别关联模型的属性？

owner_controller_test.rb

 require 'test_helper'

 class OwnershipsControllerTest < ActionController::TestCase
 test "Should retrieve index" do
 get :index
 assert_response :success
 end

 test "Should retrieve results" do
 get :round1
 assert_response :success
 end
 end

所有

 one:
 round: 1
 pick: 1
 team_id: 1
 player_id: 1

 two:
 round: 1
 pick: 1
 team_id: 1
 player_id: 1

teams.yml

 one:
 name: Browns
 division: East
 logo_file_name: logo.jpg 

 two:
 name: Chargers
 division: West
 logo_file_name: logo.jpg

楷模

 class Ownership < ActiveRecord::Base
 belongs_to :player
 belongs_to :team

 validates :round, :pick, :team_id, presence: true
 end

class Team < ActiveRecord::Base
has_many :ownerships
has_many :players, through: :ownerships 

validates :name, presence: true
validates :division, presence: true

has_attached_file :logo , :styles => { :small => '10>', :medium => '40>', :large => '60>' }
validates_attachment_content_type :logo, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
end

owners_controller.rb的相关部分

class OwnershipsController < ApplicationController

def index
@ownerships = Ownership.all.select { |t| t.player_id == nil}
Rails.application.config.counter = (256 - Ownership.all.select{ |t| t.player_id == nil}.count)
end

def round1
@ownerships = Ownership.all.select { |m| m.round == 1}
end

private
def ownership_params
params.require(:ownership).permit(:round,:pick,:team_id,:player_id)
end