Support epics autocomplete for project objects

- add epics routes to the application_helper
- create epics action in AutocompleteController

app/controllers/projects/autocomplete_sources_controller.rb

 # frozen_string_literal: true
 
 class Projects::AutocompleteSourcesController < Projects::ApplicationController
-  before_action :load_autocomplete_service, except: [:members]
+  prepend EE::Projects::AutocompleteSourcesController
 
   def members
     render json: ::Projects::ParticipantsService.new(@project, current_user).execute(target)
   end
 
   def issues
-    render json: @autocomplete_service.issues
+    render json: autocomplete_service.issues
   end
 
   def merge_requests
-    render json: @autocomplete_service.merge_requests
+    render json: autocomplete_service.merge_requests
   end
 
   def labels
-    render json: @autocomplete_service.labels_as_hash(target)
+    render json: autocomplete_service.labels_as_hash(target)
   end
 
   def milestones
-    render json: @autocomplete_service.milestones
+    render json: autocomplete_service.milestones
   end
 
   def commands
-    render json: @autocomplete_service.commands(target, params[:type])
+    render json: autocomplete_service.commands(target, params[:type])
   end
 
   def snippets
-    render json: @autocomplete_service.snippets
+    render json: autocomplete_service.snippets
   end
 
   private
 
-  def load_autocomplete_service
-    @autocomplete_service = ::Projects::AutocompleteService.new(@project, current_user)
+  def autocomplete_service
+    @autocomplete_service ||= ::Projects::AutocompleteService.new(@project, current_user)
   end
 
   def target

app/services/projects/autocomplete_service.rb

@@ -2,6 +2,8 @@
 
 module Projects
   class AutocompleteService < BaseService
+    prepend EE::Projects::AutocompleteService
+
     include LabelsAsHash
     def issues
       IssuesFinder.new(current_user, project_id: project.id, state: 'opened').execute.select([:iid, :title])

ee/app/controllers/ee/projects/autocomplete_sources_controller.rb

+# frozen_string_literal: true
+
+module EE
+  module Projects
+    module AutocompleteSourcesController
+      extend ActiveSupport::Concern
+
+      def epics
+        return render_404 unless project.group.feature_available?(:epics)
+
+        render json: autocomplete_service.epics
+      end
+    end
+  end
+end

ee/app/helpers/ee/application_helper.rb

@@ -65,14 +65,18 @@ module EE
     def autocomplete_data_sources(object, noteable_type)
       return {} unless object && noteable_type
 
-      return super unless object.is_a?(Group)
-
-      {
-        members: members_group_autocomplete_sources_path(object, type: noteable_type, type_id: params[:id]),
-        labels: labels_group_autocomplete_sources_path(object),
-        epics: epics_group_autocomplete_sources_path(object),
-        commands: commands_group_autocomplete_sources_path(object, type: noteable_type, type_id: params[:id])
-      }
+      if object.is_a?(Group)
+        {
+          members: members_group_autocomplete_sources_path(object, type: noteable_type, type_id: params[:id]),
+          labels: labels_group_autocomplete_sources_path(object),
+          epics: epics_group_autocomplete_sources_path(object),
+          commands: commands_group_autocomplete_sources_path(object, type: noteable_type, type_id: params[:id])
+        }
+      elsif object.group&.feature_available?(:epics)
+        { epics: epics_project_autocomplete_sources_path(object) }.merge(super)
+      else
+        super
+      end
     end
 
     def instance_review_permitted?

ee/app/services/ee/projects/autocomplete_service.rb

+# frozen_string_literal: true
+module EE
+  module Projects
+    module AutocompleteService
+      def epics
+        EpicsFinder
+          .new(current_user, group_id: project.group&.id, state: 'opened')
+          .execute.select([:iid, :title])
+      end
+    end
+  end
+end

ee/changelogs/unreleased/7472-epics-autocomplete.yml

+---
+title: Support epics autocomplete for project objects
+merge_request: 8180
+author:
+type: added

ee/config/routes/project.rb

+# frozen_string_literal: true
+
+constraints(::Constraints::ProjectUrlConstrainer.new) do
+  scope(path: '*namespace_id',
+        as: :namespace,
+        namespace_id: Gitlab::PathRegex.full_namespace_route_regex) do
+    scope(path: ':project_id',
+          constraints: { project_id: Gitlab::PathRegex.project_route_regex },
+          module: :projects,
+          as: :project) do
+      resources :autocomplete_sources, only: [] do
+        collection do
+          get 'epics'
+        end
+      end
+    end
+  end
+end

ee/spec/controllers/ee/projects/autocomplete_sources_controller_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+describe Projects::AutocompleteSourcesController do
+  set(:user) { create(:user) }
+  set(:group) { create(:group) }
+  set(:group2) { create(:group) }
+  set(:project) { create(:project, :public, group: group) }
+  set(:epic) { create(:epic, group: group) }
+  set(:epic2) { create(:epic, group: group2) }
+
+  before do
+    sign_in(user)
+  end
+
+  context 'when epics feture is disabled' do
+    it 'returns 404 status' do
+      get :epics, namespace_id: project.namespace, project_id: project
+
+      expect(response).to have_gitlab_http_status(404)
+    end
+  end
+
+  context 'when epics feture is enabled' do
+    before do
+      stub_licensed_features(epics: true)
+    end
+
+    context '#epics' do
+      it 'returns the correct response' do
+        get :epics, namespace_id: project.namespace, project_id: project
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response).to be_an(Array)
+        expect(json_response.count).to eq(1)
+        expect(json_response.first).to include(
+          'iid' => epic.iid, 'title' => epic.title
+        )
+      end
+    end
+  end
+end

ee/spec/controllers/groups/autocomplete_sources_controller_spec.rb

-# frozen_string_literal: tru
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Groups::AutocompleteSourcesController do

ee/spec/helpers/application_helper_spec.rb

@@ -23,8 +23,26 @@ describe ApplicationHelper do
       let(:object) { create(:project) }
       let(:noteable_type) { Issue }
 
-      it 'returns paths for autocomplete_sources_controller' do
-        expect_autocomplete_data_sources(object, noteable_type, [:members, :issues, :mergeRequests, :labels, :milestones, :commands, :snippets])
+      context 'when epics are enabled' do
+        before do
+          stub_licensed_features(epics: true)
+        end
+
+        it 'returns paths for autocomplete_sources_controller for personal projects' do
+          expect_autocomplete_data_sources(object, noteable_type, [:members, :issues, :mergeRequests, :labels, :milestones, :commands, :snippets])
+        end
+
+        it 'returns paths for autocomplete_sources_controller including epics for group projects' do
+          object.update(group: create(:group))
+
+          expect_autocomplete_data_sources(object, noteable_type, [:members, :issues, :mergeRequests, :labels, :milestones, :commands, :snippets, :epics])
+        end
+      end
+
+      context 'when epics are disabled' do
+        it 'returns paths for autocomplete_sources_controller' do
+          expect_autocomplete_data_sources(object, noteable_type, [:members, :issues, :mergeRequests, :labels, :milestones, :commands, :snippets])
+        end
       end
     end
   end