在多态注释控制器 Rspec 中测试创建操作 - nil：NilClass 的未定义方法"注释"

Question

我正试图在多态注释控制器中测试POST创建操作。当运行下面的规范时，他们失败了，并出现错误：

undefined method `comments' for nil:NilClass

我认为这意味着@commentable没有被正确创建/设置，所以它不存在。ATM我正在清除load_commentable方法并返回FactoryGirl问题对象，但这似乎仍然不能解决任何问题。

我如何修改我的规范，以便正确创建commentable对象，并在@commutable的范围内创建注释，就像在实际控制器中一样？

comments_controller.rb

def create 
    @comment = @commentable.comments.build(params[:comment])
    @comment.user_id = current_user.id
    respond_to do |format|
    if @comment.save
        format.html { redirect_to @commentable, notice: 'Comment created'}
        format.js
    else
      format.html { redirect_to @commentable, notice: "Content can't be blank" }
      format.js
      end
    end
  end
def load_commentable
    resource, id = request.path.split('/')[1,2]
    @commentable = resource.singularize.classify.constantize.find(id)
  end

comments_controller_spec.rb

describe CommentsController do
  include Devise::TestHelpers
  include AnswerHelper
  before(:each) do
    @user = create(:user)
    @user2 = create(:user)
    sign_in @user
    sign_in @user2
    @commentable = create(:question, user: @user2)
    @comment = create(:comment, user: @user)
    @vote = attributes_for(:vote, user: @user2, votable_id: @commentable)
    controller.stub!(:load_commentable).and_return(@commentable)
    controller.stub!(:current_user).and_return(@user)
    @request.env['HTTP_REFERER'] = "http://test.host/questions/#{@commentable.id}"
    stub_model_methods
  end
  describe "POST create" do
    describe "with valid params" do
      it "creates a new comment" do
        expect {
          post :create, comment: attributes_for(:comment), commentable: @commentable
        }.to change(Comment, :count).by(1)
      end
      it "assigns a newly created comment as @comment" do
        post :create, comment: attributes_for(:comment), commentable: @commentable
        assigns(:comment).should be_a(Comment)
        assigns(:comment).should be_persisted
      end
    end
    describe "with invalid params" do
      it "assigns a newly created but unsaved comment as @comment" do
        Comment.any_instance.stub(:save).and_return(false)
        post :create, comment: attributes_for(:comment), commentable: @commentable
        assigns(:comment).should be_a_new(Comment)
      end
    end
  end

factory.rb

factory :comment do
    user
    commentable_id :question
    commentable_type "Question"
    content "a comment"
    votes_count 5
  end

rspec恢复

1) CommentsController POST create with valid params creates a new comment
     Failure/Error: post :create, comment: attributes_for(:comment), commentable: @commentable
     NoMethodError:
       undefined method `comments' for nil:NilClass
     # ./app/controllers/comments_controller.rb:19:in `create'
     # ./spec/controllers/comments_controller_spec.rb:24:in `block (5 levels) in <top (required)>'
     # ./spec/controllers/comments_controller_spec.rb:23:in `block (4 levels) in <top (required)>'

Answer 1

这里的问题是您正在清除load_commentable，它负责在控制器中设置实例变量@commentable。由于您正在对其进行存根处理，因此永远不会调用它，也永远不会设置ivar——您不能直接从rspec测试套件在控制器中设置ivar。

由于您正在创建一个记录，因此实际上不需要存根任何内容，只需传递@commentable.id，然后让它从数据库中查找即可。不过，如果你出于某种原因想避免被发现，你可以使用：

Question.stub(:find).with(@commentable.id).and_return(@commentable)

这将导致控制器使用@commentable对象，并将其分配给控制器中的@commentable，此时测试应继续正常运行。