title: RSpec match_array fail even when arrays are the same
body: <p><strong>Note:</strong> my app works just fine. I'm just unable to do the right rspec for it.</p>
  
  <p><strong>trash_controller.rb:</strong></p>
  
  <pre><code>class TrashController &lt; ApplicationController
      before_action :set_slide, only: [ :show, :destroy, :restore ]
  
      def set_slide
          @trashed_slide = Slide.only_deleted.find(params[:id])
      end
  
      def show
      end
  </code></pre>
  
  <p><strong>trash_controller_spec.rb:</strong></p>
  
  <pre><code>describe TrashController do
  
    let(:album) { create(:album) }
    let(:slide) { build(:slide) }
  
    describe "GET #show" do
      before do
        slide.save
        slide.destroy        
        get :show, id: slide.id
      end
  
      it { expect(assigns(:trashed_slide)).to match_array(Slide.only_deleted.to_a) } 
    end
  </code></pre>
  
  <p>error:</p>
  
  <pre><code>1) TrashController GET #show should contain exactly #&lt;Slide id: 1, album_id: 1, description: "Brennon Prosacco", created_at: "2014-04-02 06:06:03", updated_at: "2014-04-02 06:06:03", photo_file_name: "sample_2.jpg", photo_content_type: "image/jpeg", photo_file_size: 204509, photo_updated_at: "2014-04-02 06:06:03", photo_fingerprint: "4dbd1870094527b8c4ddca6afd415eb9", deleted_at: "2014-04-02 06:06:03", photo_processing: false&gt;
       Failure/Error: it { expect(assigns(:trashed_slide)).to match_array(Slide.only_deleted.to_a) }
         expected an array, actual collection was #&lt;Slide id: 1, album_id: 1, description: "Brennon Prosacco", created_at: "2014-04-02 06:06:03", updated_at: "2014-04-02 06:06:03", photo_file_name: "sample_2.jpg", photo_content_type: "image/jpeg", photo_file_size: 204509, photo_updated_at: "2014-04-02 06:06:03", photo_fingerprint: "4dbd1870094527b8c4ddca6afd415eb9", deleted_at: "2014-04-02 06:06:03", photo_processing: false&gt;
       # ./spec/controllers/trash_controller_spec.rb:25:in `block (3 levels) in &lt;top (required)&gt;'
  </code></pre>
  
  <p>I don't get what it's about as both lines looks the same. Any ideas ?</p>