```ruby
require 'rails_helper'

describe Resource, type: :model do
end
```

Add tests for Resource upload behavior
user
```ruby
require 'rails_helper'

describe Resource, type: :model do
  describe '#upload' do
    let(:blog) { create :blog }
    let(:resource) { create :resource, blog: blog }
    let(:img_resource) { Resource.create blog: blog, upload: file_upload('testfile.png', 'image/png') }

    it 'stores files in the correct location' do
      expected_path = Rails.root.join('public', 'files/resource/1', 'testfile.txt')
      expect(resource.upload.file.file).to eq expected_path.to_s
    end

    it 'stores resized images in the correct location' do
      thumb_path = Rails.root.join('public', 'files/resource/1', 'thumb_testfile.png')
      expect(img_resource.upload.thumb.file.file).to eq thumb_path.to_s
    end

    it 'creates three image versions' do
      expect(img_resource.upload.versions.keys).to match_array [:thumb, :medium, :avatar]
    end

    it 'gives the correct url for the attachment' do
      expect(resource.upload_url).to eq '/files/resource/1/testfile.txt'
    end

    it 'gives the correct url for the image versions' do
      expect(img_resource.upload_url(:thumb)).to eq '/files/resource/1/thumb_testfile.png'
    end
  end
end
```
assistant