ruby-on-rails-3 - 无法从辅助模块访问 image_tag

Question

我想测试以下辅助模块功能:

module UploadsHelper

  def custom_img_tag(upload, width, height, id)
     if width > Upload::MAX_CROP_WIDTH
       image_tag(upload.photo.url(:original), :id => "box", :width => Upload::MAX_CROP_WIDTH, :height => (height*Upload::MAX_CROP_WIDTH/width).to_i)
     else
       image_tag(upload.photo.url(:original), :id => "box")
     end
   end

end

但是当我运行以下测试时:

describe UploadsController do
  include UploadsHelper
    describe "custom_img_tag(upload, width, height, id)" do
           before(:each) do
             @upload = Factory(:upload)
             geo = Paperclip::Geometry.from_file(@upload.photo.to_file(:original))
             @width   = geo.width
             @height  = geo.height
           end

       it "should return the original image tag for an image that is not wider than  MAX_CROP_WIDTH" do
         #custom_img_tag(@upload,@width, @heigth, "cropbox" ).should == '<img id="cropbox" width="500" height="375" src="/system/photos/10/original/avatar.jpg?1311044917" alt="Avatar" style="display: none;">'
       end
     end

我收到以下错误:

Failure/Error: custom_img_tag(@upload,@width, @heigth, "cropbox" ).should == '<img id="cropbox" width="500" height="375" src="/system/photos/10/original/avatar.jpg?1311044917" alt="Avatar" style="display: none;">'
     NoMethodError:
       You have a nil object when you didn't expect it!

为什么会出现此错误以及如何测试此方法？

更新:我在规范测试文件中添加了以下内容:

include ActionView::Helpers 

这会产生以下错误:

NameError:
       undefined local variable or method `config' for #<RSpec

我怎样才能摆脱这个错误，原因是什么？

感谢您的帮助。

Answer 1

我在使用 Rails 3.1 RC 时也遇到了错误

NameError:
   undefined local variable or method `config'

一些 Rails 源代码跟踪，我发现缺少的包括 ActionView::AssetPaths。

include ActionView::AssetPaths
include ActionView::Helpers::AssetTagHelper