Assignee filter on group issues/merge requests only loads group users

Closes #29490

app/assets/javascripts/users_select.js

@@ -33,6 +33,7 @@
           var $block, $collapsedSidebar, $dropdown, $loading, $selectbox, $value, abilityName, assignTo, assigneeTemplate, collapsedAssigneeTemplate, defaultLabel, firstUser, issueURL, selectedId, showAnyUser, showNullUser, showMenuAbove;
           $dropdown = $(dropdown);
           options.projectId = $dropdown.data('project-id');
+          options.groupId = $dropdown.data('group-id');
           options.showCurrentUser = $dropdown.data('current-user');
           options.todoFilter = $dropdown.data('todo-filter');
           options.todoStateFilter = $dropdown.data('todo-state-filter');

app/views/shared/issuable/_filter.html.haml

@@ -21,7 +21,7 @@
           - if params[:assignee_id].present?
             = hidden_field_tag(:assignee_id, params[:assignee_id])
           = dropdown_tag(user_dropdown_label(params[:assignee_id], "Assignee"), options: { toggle_class: "js-user-search js-filter-submit js-assignee-search", title: "Filter by assignee", filter: true, dropdown_class: "dropdown-menu-user dropdown-menu-selectable dropdown-menu-assignee js-filter-submit",
-            placeholder: "Search assignee", data: { any_user: "Any Assignee", first_user: current_user.try(:username), null_user: true, current_user: true, project_id: @project.try(:id), selected: params[:assignee_id], field_name: "assignee_id", default_label: "Assignee" } })
+            placeholder: "Search assignee", data: { any_user: "Any Assignee", first_user: current_user.try(:username), null_user: true, current_user: true, project_id: @project.try(:id), group_id: @group&.id, selected: params[:assignee_id], field_name: "assignee_id", default_label: "Assignee" } })
 
         .filter-item.inline.milestone-filter
           = render "shared/issuable/milestone_dropdown", selected: finder.milestones.try(:first), name: :milestone_title, show_any: true, show_upcoming: true, show_started: true

changelogs/unreleased/group-assignee-dropdown-send-group-id.yml

@@ -0,0 +1,4 @@
+---
+title: Fixed group issues assignee dropdown loading all users
+merge_request:
+author:

spec/features/groups/issues_spec.rb

@@ -23,4 +23,20 @@ feature 'Group issues page', feature: true do
       it_behaves_like "an autodiscoverable RSS feed without a private token"
     end
   end
+
+  context 'assignee', :js do
+    let(:access_level) { ProjectFeature::ENABLED }
+    let(:user) { user_in_group }
+    let(:user2) { user_outside_group }
+    let(:path) { issues_group_path(group) }
+
+    it 'filters by only group users' do
+      click_button('Assignee')
+
+      wait_for_ajax
+
+      expect(find('.dropdown-menu-assignee')).to have_link(user.name)
+      expect(find('.dropdown-menu-assignee')).not_to have_link(user2.name)
+    end
+  end
 end