Support design notes in url generator

This ensures that we can serve events on the activity feed that are
notes on designs

ee/app/helpers/ee/events_helper.rb

@@ -8,9 +8,21 @@ module EE
     def event_note_target_url(event)
       if event.epic_note?
         group_epic_url(event.group, event.note_target, anchor: dom_id(event.target))
+      elsif event.design_note?
+        design_url(event.note_target, anchor: dom_id(event.note))
       else
         super
       end
     end
+
+    private
+
+    def design_url(design, opts)
+      designs_project_issue_url(
+        design.project,
+        design.issue,
+        opts.merge(vueroute: design.filename)
+      )
+    end
   end
 end

ee/changelogs/unreleased/ajk-fix-design-activity.yml

+---
+title: Fix error when viewing events from design notes on project activity page
+merge_request: 27840
+author:
+type: fixed

ee/spec/factories/events.rb

@@ -13,7 +13,7 @@ FactoryBot.modify do
     trait :for_design do
       transient do
         design { create(:design, issue: create(:issue, project: project)) }
-        note { create(:note, project: project, noteable: design) }
+        note { create(:note, author: author, project: project, noteable: design) }
       end
 
       action { Event::COMMENTED }

ee/spec/features/projects/activity/user_sees_design_comment_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Projects > Activity > User sees design comment', :js do
+  include DesignManagementTestHelpers
+
+  let_it_be(:project) { create(:project, :repository, :public) }
+  let_it_be(:user) { project.creator }
+  let_it_be(:commenter) { create(:user) }
+  let_it_be(:issue) { create(:closed_issue, project: project) }
+  let_it_be(:design) { create(:design, issue: issue) }
+
+  let(:design_activity) do
+    "#{commenter.name} #{commenter.to_reference} commented on design"
+  end
+
+  let(:issue_activity) do
+    "#{user.name} #{user.to_reference} closed issue #{issue.to_reference}"
+  end
+
+  before(:all) do
+    project.add_developer(commenter)
+    create(:event, :for_design, project: project, author: commenter, design: design)
+    create(:closed_issue_event, project: project, author: user, target: issue)
+  end
+
+  before do
+    enable_design_management
+  end
+
+  it 'shows the design comment action in the activity page' do
+    visit activity_project_path(project)
+
+    expect(page).to have_content(design_activity)
+  end
+
+  it 'allows to filter out the design event with the "event_filter=issue" URL param', :aggregate_failures do
+    visit activity_project_path(project, event_filter: EventFilter::ISSUE)
+
+    expect(page).not_to have_content(design_activity)
+    expect(page).to have_content(issue_activity)
+  end
+
+  it 'allows to filter in the event with the "event_filter=comments" URL param', :aggregate_failures do
+    visit activity_project_path(project, event_filter: EventFilter::COMMENTS)
+
+    expect(page).to have_content(design_activity)
+    expect(page).not_to have_content(issue_activity)
+  end
+end

ee/spec/helpers/ee/events_helper_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe EventsHelper do
+  describe '#event_note_target_url' do
+    let(:project) { event.project }
+    let(:project_base_url) { project_url(project) }
+
+    subject { helper.event_note_target_url(event) }
+
+    context 'for design note events' do
+      let(:event) { create(:event, :for_design) }
+
+      it 'returns an appropriate URL' do
+        iid      = event.note_target.issue.iid
+        filename = event.note_target.filename
+        note_id  = event.target.id
+
+        expect(subject).to eq("#{project_base_url}/-/issues/#{iid}/designs/#{filename}#note_#{note_id}")
+      end
+    end
+  end
+end