Null user should be used only for display purposes

app/decorators/asciicast_decorator.rb

@@ -3,7 +3,9 @@ class AsciicastDecorator < ApplicationDecorator
   THUMBNAIL_WIDTH = 20
   THUMBNAIL_HEIGHT = 10
 
-  decorates_association :user
+  def user
+    @user ||= UserDecorator.new(model.user || User.null)
+  end
 
   def os
     if user_agent.present?

app/models/asciicast.rb

@@ -54,10 +54,6 @@ class Asciicast < ActiveRecord::Base
     collection
   end
 
-  def user
-    super || self.user = User.null
-  end
-
   def stdout
     return @stdout if @stdout
     @stdout = Stdout::Buffered.new(get_stdout)

spec/decorators/asciicast_decorator_spec.rb

@@ -240,32 +240,6 @@ describe AsciicastDecorator do
     end
   end
 
-  describe '#author_link' do
-    subject { decorator.author_link }
-
-    let(:asciicast) { double('asciicast', user: user) }
-    let(:user) { double('user', link: 'link') }
-
-    before do
-      allow(user).to receive(:decorate) { user }
-    end
-
-    it { should eq('link') }
-  end
-
-  describe '#author_img_link' do
-    subject { decorator.author_img_link }
-
-    let(:asciicast) { double('asciicast', user: user) }
-    let(:user) { double('user', img_link: 'img-link') }
-
-    before do
-      allow(user).to receive(:decorate) { user }
-    end
-
-    it { should eq('img-link') }
-  end
-
   describe '#formatted_duration' do
     subject { decorator.formatted_duration }
 

spec/models/asciicast_spec.rb

@@ -54,26 +54,6 @@ describe Asciicast do
 
   let(:asciicast) { described_class.new }
 
-  describe '#user' do
-    subject { asciicast.user }
-
-    context "when it has user assigned" do
-      let(:user) { User.new }
-
-      before do
-        asciicast.user = user
-      end
-
-      it { should be(user) }
-    end
-
-    context "when it doesn't have user assigned" do
-      it 'is a null user' do
-        expect(asciicast.user.temporary_username).to eq('anonymous')
-      end
-    end
-  end
-
   describe '#stdout' do
     context 'for single-file, JSON asciicast' do
       let(:asciicast) { create(:asciicast) }