Merge branch 'id-refactor-view-testing' into 'master'

Fix view rendering that fails in Rails 6.1

See merge request gitlab-org/gitlab!60817

ee/app/services/merge_requests/create_from_vulnerability_data_service.rb

@@ -85,8 +85,7 @@ module MergeRequests
     end
 
     def render_template(file:, locals:)
-      view = ActionView::Base.new(ActionController::Base.view_paths, {})
-      view.render(file: file, locals: locals)
+      ActionController::Base.new.render_to_string(template: file, locals: locals)
     end
 
     def can_create_merge_request?(source_branch)

ee/spec/views/admin/dev_ops_report/show.html.haml_spec.rb

@@ -3,23 +3,13 @@
 require 'spec_helper'
 
 RSpec.describe 'admin/dev_ops_report/show.html.haml' do
-  include Devise::Test::ControllerHelpers
-
   before do
     stub_licensed_features(devops_adoption: true)
   end
 
   context 'when show_adoption? returns false' do
     before do
-      controller.singleton_class.class_eval do
-        protected
-
-        def show_adoption?
-          false
-        end
-
-        helper_method :show_adoption?
-      end
+      allow(view).to receive(:show_adoption?).and_return(false)
     end
 
     it 'disables the feature' do
@@ -40,19 +30,9 @@ RSpec.describe 'admin/dev_ops_report/show.html.haml' do
   end
 
   context 'when show_adoption? returns true' do
-    before do
-      controller.singleton_class.class_eval do
-        protected
-
-        def show_adoption?
-          true
-        end
-
-        helper_method :show_adoption?
-      end
-    end
-
     it 'enables the feature' do
+      allow(view).to receive(:show_adoption?).and_return(true)
+
       render
 
       expect(rendered).to have_selector('#devops-adoption')

spec/views/shared/nav/_sidebar.html.haml_spec.rb

@@ -32,7 +32,7 @@ RSpec.describe 'shared/nav/_sidebar.html.haml' do
     context 'when sidebar has a custom scope menu partial defined' do
       it 'renders the custom partial' do
         allow(sidebar).to receive(:render_raw_scope_menu_partial).and_return(scope_menu_view)
-        allow(sidebar).to receive(:scope_menu).and_return(nil)
+        allow(view).to receive(:scope_menu).and_return(nil)
         stub_template(scope_menu_partial => content)
 
         render