Show service templates nav based on FF

Put Service Templates nav item behind a featureflag,
currently disabled by default. When enabled,
the link won't be present in the UI.

app/helpers/services_helper.rb

@@ -172,6 +172,14 @@ module ServicesHelper
       name: integration.to_param
     }
   end
+
+  def service_templates_enabled?
+    Feature.disabled?(:disable_service_templates, type: :development, default_enabled: :yaml)
+  end
+
+  def show_service_templates_nav_link?
+    service_templates_enabled?
+  end
 end
 
 ServicesHelper.prepend_if_ee('EE::ServicesHelper')

app/views/layouts/nav/sidebar/_admin.html.haml

@@ -202,17 +202,18 @@
 
       = render_if_exists 'layouts/nav/sidebar/credentials_link'
 
-      = nav_link(controller: :services) do
-        = link_to admin_application_settings_services_path do
-          .nav-icon-container
-            = sprite_icon('template')
-          %span.nav-item-name
-            = _('Service Templates')
-        %ul.sidebar-sub-level-items.is-fly-out-only
-          = nav_link(controller: :services, html_options: { class: "fly-out-top-item" } ) do
-            = link_to admin_application_settings_services_path do
-              %strong.fly-out-top-item-name
-                = _('Service Templates')
+      - if show_service_templates_nav_link?
+        = nav_link(controller: :services) do
+          = link_to admin_application_settings_services_path do
+            .nav-icon-container
+              = sprite_icon('template')
+            %span.nav-item-name
+              = _('Service Templates')
+          %ul.sidebar-sub-level-items.is-fly-out-only
+            = nav_link(controller: :services, html_options: { class: "fly-out-top-item" } ) do
+              = link_to admin_application_settings_services_path do
+                %strong.fly-out-top-item-name
+                  = _('Service Templates')
 
       = nav_link(controller: :labels) do
         = link_to admin_labels_path do

config/feature_flags/development/disable_service_templates.yml

+---
+name: disable_service_templates
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/59098
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/327436
+milestone: '13.12'
+type: development
+group: group::ecosystem
+default_enabled: false

spec/features/admin/admin_settings_spec.rb

@@ -251,41 +251,64 @@ RSpec.describe 'Admin updates settings' do
       end
     end
 
-    context 'when the Slack Notifications Service template is active' do
+    context 'when Service Templates are enabled' do
       before do
-        create(:service, :template, type: 'SlackService', active: true)
+        stub_feature_flags(disable_service_templates: false)
+      end
 
-        visit general_admin_application_settings_path
+      context 'when no service templates are active' do
+        it 'does not show Service Templates link' do
+          expect(page).not_to have_link('Service Templates')
+        end
       end
 
-      it 'change Slack Notifications Service template settings', :js do
-        first(:link, 'Service Templates').click
-        click_link 'Slack notifications'
-        fill_in 'Webhook', with: 'http://localhost'
-        fill_in 'Username', with: 'test_user'
-        fill_in 'service[push_channel]', with: '#test_channel'
-        page.check('Notify only broken pipelines')
-        page.select 'All branches', from: 'Branches to be notified'
-        page.select 'Match any of the labels', from: 'Labels to be notified behavior'
+      context 'when the Slack Notifications Service template is active' do
+        before do
+          stub_feature_flags(disable_service_templates: false)
+          create(:service, :template, type: 'SlackService', active: true)
 
-        check_all_events
-        click_button 'Save changes'
+          visit general_admin_application_settings_path
+        end
 
-        expect(page).to have_content 'Application settings saved successfully'
+        it 'change Slack Notifications Service template settings', :js do
+          first(:link, 'Service Templates').click
+          click_link 'Slack notifications'
+          fill_in 'Webhook', with: 'http://localhost'
+          fill_in 'Username', with: 'test_user'
+          fill_in 'service[push_channel]', with: '#test_channel'
+          page.check('Notify only broken pipelines')
+          page.select 'All branches', from: 'Branches to be notified'
+          page.select 'Match any of the labels', from: 'Labels to be notified behavior'
+
+          check_all_events
+          click_button 'Save changes'
 
-        click_link 'Slack notifications'
+          expect(page).to have_content 'Application settings saved successfully'
 
-        expect(page.all('input[type=checkbox]')).to all(be_checked)
-        expect(find_field('Webhook').value).to eq 'http://localhost'
-        expect(find_field('Username').value).to eq 'test_user'
-        expect(find('[name="service[push_channel]"]').value).to eq '#test_channel'
+          click_link 'Slack notifications'
+
+          expect(page.all('input[type=checkbox]')).to all(be_checked)
+          expect(find_field('Webhook').value).to eq 'http://localhost'
+          expect(find_field('Username').value).to eq 'test_user'
+          expect(find('[name="service[push_channel]"]').value).to eq '#test_channel'
+        end
+
+        it 'defaults Deployment events to false for chat notification template settings', :js do
+          first(:link, 'Service Templates').click
+          click_link 'Slack notifications'
+
+          expect(find_field('Deployment')).not_to be_checked
+        end
       end
+    end
 
-      it 'defaults Deployment events to false for chat notification template settings', :js do
-        first(:link, 'Service Templates').click
-        click_link 'Slack notifications'
+    context 'When Service templates are disabled' do
+      before do
+        stub_feature_flags(disable_service_templates: true)
+      end
 
-        expect(find_field('Deployment')).not_to be_checked
+      it 'does not show Service Templates link' do
+        expect(page).not_to have_link('Service Templates')
       end
     end