Show the admin/settings menu for any of its elements

It's possible to create permission sets the only give access to a
subset of the settings menu items, without this the settings menu was
kept hidden.

backend/lib/spree/backend_configuration.rb

@@ -131,7 +131,20 @@ def menu_items
         MenuItem.new(
           CONFIGURATION_TABS,
           'wrench',
-          condition: -> { can?(:admin, Spree::Store) },
+          condition: -> {
+            can?(:admin, Spree::Store) ||
+            can?(:show, Spree::AdjustmentReason) ||
+            can?(:show, Spree::PaymentMethod) ||
+            can?(:show, Spree::RefundReason) ||
+            can?(:show, Spree::ReimbursementType) ||
+            can?(:show, Spree::ShippingCategory) ||
+            can?(:show, Spree::ShippingMethod) ||
+            can?(:show, Spree::StockLocation) ||
+            can?(:show, Spree::TaxCategory) ||
+            can?(:show, Spree::TaxRate) ||
+            can?(:show, Spree::ReturnReason) ||
+            can?(:show, Spree::Zone)
+          },
           label: :settings,
           partial: 'spree/admin/shared/settings_sub_menu',
           url: :admin_stores_path,

backend/spec/lib/spree/backend_configuration_spec.rb

@@ -18,5 +18,17 @@
         expect(stock_menu_item.match_path).to eq('/stock_items')
       end
     end
+
+    describe 'menu tab for settings' do
+      let(:menu_item) do
+        subject.find { |item| item.label == :settings }
+      end
+
+      it 'is shown if any of its submenus are present' do
+        view = double("view", can?: false)
+        expect(view).to receive(:can?).at_least(12).times
+        view.instance_exec(&menu_item.condition)
+      end
+    end
   end
 end