Adds the attention required property to the sidebar API

Adds the `attention_required` property to the assignees
and reviewers entities in the sidebar API.

app/controllers/projects/merge_requests_controller.rb

@@ -142,8 +142,8 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
           cache_context = [
             params[:serializer],
             current_user&.cache_key,
-            @merge_request.assignees.map(&:cache_key),
-            @merge_request.reviewers.map(&:cache_key)
+            @merge_request.merge_request_assignees.map(&:cache_key),
+            @merge_request.merge_request_reviewers.map(&:cache_key)
           ]
 
           render_cached(@merge_request,

app/models/merge_request.rb

@@ -1942,6 +1942,10 @@ class MergeRequest < ApplicationRecord
     end
   end
 
+  def attention_required_enabled?
+    Feature.enabled?(:mr_attention_requests, project, default_enabled: :yaml)
+  end
+
   private
 
   def set_draft_status

app/models/merge_request_assignee.rb

@@ -9,4 +9,8 @@ class MergeRequestAssignee < ApplicationRecord
   validates :assignee, uniqueness: { scope: :merge_request_id }
 
   scope :in_projects, ->(project_ids) { joins(:merge_request).where(merge_requests: { target_project_id: project_ids }) }
+
+  def cache_key
+    [model_name.cache_key, id, state, assignee.cache_key]
+  end
 end

app/models/merge_request_reviewer.rb

@@ -5,4 +5,8 @@ class MergeRequestReviewer < ApplicationRecord
 
   belongs_to :merge_request
   belongs_to :reviewer, class_name: 'User', foreign_key: :user_id, inverse_of: :merge_request_reviewers
+
+  def cache_key
+    [model_name.cache_key, id, state, reviewer.cache_key]
+  end
 end

app/serializers/merge_request_sidebar_extras_entity.rb

@@ -2,10 +2,10 @@
 
 class MergeRequestSidebarExtrasEntity < IssuableSidebarExtrasEntity
   expose :assignees do |merge_request, options|
-    MergeRequestUserEntity.represent(merge_request.assignees, options.merge(merge_request: merge_request))
+    MergeRequestUserEntity.represent(merge_request.assignees, options.merge(merge_request: merge_request, type: :assignees))
   end
 
   expose :reviewers do |merge_request, options|
-    MergeRequestUserEntity.represent(merge_request.reviewers, options.merge(merge_request: merge_request))
+    MergeRequestUserEntity.represent(merge_request.reviewers, options.merge(merge_request: merge_request, type: :reviewers))
   end
 end

app/serializers/merge_request_user_entity.rb

@@ -16,10 +16,12 @@ class MergeRequestUserEntity < ::API::Entities::UserBasic
     request.current_user&.can?(:update_merge_request, options[:merge_request])
   end
 
-  expose :reviewed, if: satisfies(:present?, :allows_reviewers?) do |reviewer, options|
-    reviewer = options[:merge_request].find_reviewer(reviewer)
+  expose :reviewed, if: satisfies(:present?, :allows_reviewers?) do |user, options|
+    find_reviewer_or_assignee(user, options)&.reviewed?
+  end
 
-    reviewer&.reviewed?
+  expose :attention_required, if: satisfies(:present?, :allows_reviewers?, :attention_required_enabled?) do |user, options|
+    find_reviewer_or_assignee(user, options)&.attention_required?
   end
 
   expose :approved, if: satisfies(:present?) do |user, options|
@@ -27,6 +29,16 @@ class MergeRequestUserEntity < ::API::Entities::UserBasic
     # makes one query per merge request, whereas #approved_by? makes one per user
     options[:merge_request].approvals.any? { |app| app.user_id == user.id }
   end
+
+  private
+
+  def find_reviewer_or_assignee(user, options)
+    if options[:type] == :reviewers
+      options[:merge_request].find_reviewer(user)
+    else
+      options[:merge_request].find_assignee(user)
+    end
+  end
 end
 
 MergeRequestUserEntity.prepend_mod_with('MergeRequestUserEntity')

spec/serializers/merge_request_user_entity_spec.rb

@@ -4,7 +4,7 @@ require 'spec_helper'
 
 RSpec.describe MergeRequestUserEntity do
   let_it_be(:user) { create(:user) }
-  let_it_be(:merge_request) { create(:merge_request) }
+  let_it_be(:merge_request) { create(:merge_request, assignees: [user]) }
 
   let(:request) { EntityRequest.new(project: merge_request.target_project, current_user: user) }
 
@@ -18,7 +18,8 @@ RSpec.describe MergeRequestUserEntity do
     it 'exposes needed attributes' do
       is_expected.to include(
         :id, :name, :username, :state, :avatar_url, :web_url,
-        :can_merge, :can_update_merge_request, :reviewed, :approved
+        :can_merge, :can_update_merge_request, :reviewed, :approved,
+        :attention_required
       )
     end
 
@@ -56,6 +57,10 @@ RSpec.describe MergeRequestUserEntity do
       end
     end
 
+    context 'attention_required' do
+      it { is_expected.to include(attention_required: true ) }
+    end
+
     describe 'performance' do
       let_it_be(:user_a) { create(:user) }
       let_it_be(:user_b) { create(:user) }