Do not display the "Add widget" button unless the available widgets are loaded.

Fixing flaky specs related to displaying empty add widget modals.

frontend/src/app/shared/components/grids/grid/add-widget.service.ts

@@ -16,14 +16,16 @@ import { I18nService } from 'core-app/core/i18n/i18n.service';
 export class GridAddWidgetService {
   text = { add: this.i18n.t('js.grid.add_widget') };
 
-  constructor(readonly opModalService:OpModalService,
+  constructor(
+    readonly opModalService:OpModalService,
     readonly injector:Injector,
     readonly halResource:HalResourceService,
     readonly layout:GridAreaService,
     readonly drag:GridDragAndDropService,
     readonly move:GridMoveService,
     readonly resize:GridResizeService,
-    readonly i18n:I18nService) {
+    readonly i18n:I18nService
+  ) {
   }
 
   public isAddable(area:GridArea) {
@@ -120,6 +122,6 @@ export class GridAddWidgetService {
   }
 
   public get isAllowed() {
-    return this.layout.gridResource && this.layout.gridResource.updateImmediately;
+    return this.layout.gridResource && this.layout.gridResource.updateImmediately && this.layout.schema;
   }
 }

modules/grids/spec/support/pages/grid.rb

@@ -83,17 +83,21 @@ module Pages
       area = area_of(row_number, column_number, location)
       area.hover
 
-      add_widget_button = if using_cuprite?
-                            area.find(".grid--widget-add")
-                          else
-                            area.find(".grid--widget-add", visible: :all)
-                          end
+      enable_add_widget_mode_for(area)
 
+      add_widget_button = area.find(".grid--widget-add")
       add_widget_button.click
 
       within(".spot-modal", &)
     end
 
+    def enable_add_widget_mode_for(area)
+      within('.toolbar-items') do
+        button = find_button "Add widget"
+        button.click if button[:class].exclude? "-active"
+      end
+    end
+
     def expect_widget_adding_prohibited_generally(row_number = 1, column_number = 1)
       area = area_of(row_number, column_number)
       area.hover