extract favicon logic to lib class

app/helpers/appearances_helper.rb

@@ -33,8 +33,4 @@ module AppearancesHelper
       render 'shared/logo_type.svg'
     end
   end
-
-  def brand_favicon
-    brand_item&.favicon
-  end
 end

app/helpers/page_layout_helper.rb

@@ -39,11 +39,7 @@ module PageLayoutHelper
   end
 
   def favicon
-    return brand_favicon.default.url if brand_favicon
-    return 'favicon-yellow.ico' if Gitlab::Utils.to_boolean(ENV['CANARY'])
-    return 'favicon-blue.ico' if Rails.env.development?
-
-    'favicon.ico'
+    Gitlab::Favicon.default
   end
 
   def page_image

lib/gitlab/favicon.rb

+module Gitlab
+  class Favicon
+    class << self
+      def default
+        return appearance_favicon.default.url if appearance_favicon
+        return 'favicon-yellow.ico' if Gitlab::Utils.to_boolean(ENV['CANARY'])
+        return 'favicon-blue.ico' if Rails.env.development?
+
+        'favicon.ico'
+      end
+
+      private
+
+      def appearance
+        @appearance ||= Appearance.current
+      end
+
+      def appearance_favicon
+        appearance&.favicon
+      end
+    end
+  end
+end

spec/helpers/page_layout_helper_spec.rb

@@ -40,28 +40,6 @@ describe PageLayoutHelper do
     end
   end
 
-  describe 'favicon' do
-    it 'defaults to favicon.ico' do
-      allow(Rails).to receive(:env).and_return(ActiveSupport::StringInquirer.new('production'))
-      expect(helper.favicon).to eq 'favicon.ico'
-    end
-
-    it 'has blue favicon for development' do
-      allow(Rails).to receive(:env).and_return(ActiveSupport::StringInquirer.new('development'))
-      expect(helper.favicon).to eq 'favicon-blue.ico'
-    end
-
-    it 'has yellow favicon for canary' do
-      stub_env('CANARY', 'true')
-      expect(helper.favicon).to eq 'favicon-yellow.ico'
-    end
-
-    it 'uses the custom favicon if an favicon appearance is present' do
-      create :appearance, favicon: fixture_file_upload(Rails.root.join('spec/fixtures/dk.png'))
-      expect(helper.favicon).to match %r{/uploads/-/system/appearance/favicon/\d+/default_dk.ico}
-    end
-  end
-
   describe 'page_image' do
     it 'defaults to the GitLab logo' do
       expect(helper.page_image).to match_asset_path 'assets/gitlab_logo.png'

spec/lib/gitlab/favicon_spec.rb

+require 'rails_helper'
+
+RSpec.describe Gitlab::Favicon do
+  describe '.default' do
+    it 'defaults to favicon.ico' do
+      allow(Rails).to receive(:env).and_return(ActiveSupport::StringInquirer.new('production'))
+      expect(described_class.default).to eq 'favicon.ico'
+    end
+
+    it 'has blue favicon for development' do
+      allow(Rails).to receive(:env).and_return(ActiveSupport::StringInquirer.new('development'))
+      expect(described_class.default).to eq 'favicon-blue.ico'
+    end
+
+    it 'has yellow favicon for canary' do
+      stub_env('CANARY', 'true')
+      expect(described_class.favicon).to eq 'favicon-yellow.ico'
+    end
+
+    it 'uses the custom favicon if a favicon appearance is present' do
+      create :appearance, favicon: fixture_file_upload(Rails.root.join('spec/fixtures/dk.png'))
+      expect(described_class.default).to match %r{/uploads/-/system/appearance/favicon/\d+/default_dk.ico}
+    end
+  end
+end