Fix searching by assignee in the service desk

changelogs/unreleased-ee/3488-fix-service-desk.yml

+---
+title: Fix searching by assignee in the service desk
+merge_request: 2969
+author:
+type: fixed

ee/app/controllers/ee/projects/issues_controller.rb

@@ -12,7 +12,7 @@ module EE
 
       def service_desk
         if params[:assignee_id].present?
-          assignee = User.find_by_id(params[:assignee_id])
+          assignee = ::User.find_by_id(params[:assignee_id])
           @users.push(assignee) if assignee
         end
 

spec/ee/spec/controllers/projects/issues_controller_spec.rb

@@ -227,6 +227,12 @@ describe Projects::IssuesController do
 
         expect(assigns(:issues)).to contain_exactly(service_desk_issue_2)
       end
+
+      it 'allows an assignee to be specified by id' do
+        get_service_desk(assignee_id: other_user.id)
+
+        expect(assigns(:users)).to contain_exactly(other_user, support_bot)
+      end
     end
 
     context 'when Service Desk is not available on the project' do