Merge branch '6474-fix-assignees-list-showing-on-unsupported-license' into 'master'

Resolve "Assignee list UI should only appear in Premium or higher"

Closes #6474

See merge request gitlab-org/gitlab-ee!6171

ee/app/views/shared/issuable/_board_create_list_dropdown.html.haml

-.dropdown.prepend-left-10#js-add-list
+- if board.parent.feature_available?(:board_assignee_lists)
+  .dropdown.prepend-left-10#js-add-list
     %button.btn.btn-create.btn-inverted.d-flex.js-new-board-list{ type: "button", data: board_list_data }
       %span Add list
       = sprite_icon('chevron-down', size: 16, css_class: 'prepend-left-5 btn-new-board-list-chevron')
@@ -7,7 +8,7 @@
         %li.nav-item.dropdown-tab-item.js-tab-button-labels
           %a.active{ href: '#', role: 'tab', data: { is_link: 'true', toggle: 'tab', action: 'tab-labels', target: '#tab-labels' } }
             Label list
-      %li.nav-item.dropdown-tab-item.js-tab-button-labels
+        %li.nav-item.dropdown-tab-item.js-tab-button-assignees
           %a{ href: '#', role: 'tab', data: { is_link: 'true', toggle: 'tab', action: 'tab-assignees', target: '#tab-assignees' } }
             Assignee list
       .tab-content
@@ -18,3 +19,5 @@
         #tab-assignees.tab-pane.tab-pane-assignees.js-tab-container-assignees{ role: 'tabpanel' }
           = render partial: "shared/issuable/assignee_page_default"
       = dropdown_loading
+- else
+  = render_ce 'shared/issuable/board_create_list_dropdown', board: board

ee/spec/features/boards/boards_spec.rb

@@ -52,6 +52,45 @@ describe 'issue boards', :js do
     end
   end
 
+  context 'add list dropdown' do
+    let(:group) { create(:group) }
+    let(:project) { create(:project, :public, namespace: group) }
+
+    before do
+      project.add_master(user)
+      group.add_reporter(user)
+      login_as(user)
+    end
+
+    it 'shows tabbed dropdown with labels list and assignees list' do
+      stub_licensed_features(board_assignee_lists: true)
+
+      visit_board_page
+
+      page.within('#js-add-list') do
+        page.find('.js-new-board-list').click
+        wait_for_requests
+        expect(page).to have_css('.dropdown-menu.dropdown-menu-tabs')
+        expect(page).to have_css('.js-tab-button-labels')
+        expect(page).to have_css('.js-tab-button-assignees')
+      end
+    end
+
+    it 'shows simple dropdown with only labels list' do
+      stub_licensed_features(board_assignee_lists: false)
+
+      visit_board_page
+
+      page.within('#js-add-list') do
+        page.find('.js-new-board-list').click
+        wait_for_requests
+        expect(page).to have_css('.dropdown-menu.js-tab-container-labels')
+        expect(page).to have_content('Create lists from labels. Issues with that label appear in that list.')
+        expect(page).not_to have_css('.js-tab-button-assignees')
+      end
+    end
+  end
+
   def visit_board_page
     visit project_boards_path(project)
     wait_for_requests