Merge branch '417136-investigate-slowdown-of-pwacontroller-manifest' into 'master'

Add view cache for PWA manifest.json

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/126667



Merged-by: Frédéric Caplette <fcaplette@gitlab.com>
Approved-by: Deepika Guliani <dguliani@gitlab.com>
Approved-by: Gregory Havenga <11164960-ghavenga@users.noreply.gitlab.com>
Approved-by: Rémy Coutable <remy@rymai.me>
Reviewed-by: Rémy Coutable <remy@rymai.me>
Reviewed-by: Frédéric Caplette <fcaplette@gitlab.com>
Reviewed-by: Deepika Guliani <dguliani@gitlab.com>
Co-authored-by: Thomas Hutterer <thutterer@gitlab.com>

app/views/pwa/manifest.json.erb

+<%- cache current_appearance do %>
 {
   "name": "<%= appearance_pwa_name %>",
   "short_name": "<%= appearance_pwa_short_name %>",
@@ -33,3 +34,4 @@
   }
   <% end -%>]
 }
+<% end %>

spec/views/pwa/manifest.json.erb_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'pwa/manifest', feature_category: :navigation do
+  describe 'view caching', :use_clean_rails_memory_store_fragment_caching do
+    let(:appearance) { build_stubbed(:appearance, pwa_name: 'My GitLab') }
+
+    context 'when appearance is unchanged' do
+      it 'reuses the cached view' do
+        allow(view).to receive(:current_appearance).and_return(appearance)
+        allow(view).to receive(:appearance_pwa_name).and_call_original
+        render
+        render
+
+        expect(view).to have_received(:appearance_pwa_name).once
+      end
+    end
+
+    context 'when appearance has changed' do
+      let(:changed_appearance) { build_stubbed(:appearance, pwa_name: 'My new GitLab') }
+
+      it 'does not use the cached view' do
+        allow(view).to receive(:current_appearance).and_return(appearance)
+        allow(view).to receive(:appearance_pwa_name).and_call_original
+        render
+
+        allow(view).to receive(:current_appearance).and_return(changed_appearance)
+        render
+
+        expect(view).to have_received(:appearance_pwa_name).twice
+        expect(rendered).to have_content 'My new GitLab'
+      end
+    end
+  end
+end