Add FactoryBot to allow stubbing non ActiveRecord models

spec/support/factory_bot.rb

@@ -3,3 +3,16 @@
 FactoryBot::SyntaxRunner.class_eval do
   include RSpec::Mocks::ExampleMethods
 end
+
+# Patching FactoryBot to allow stubbing non AR models
+# See https://github.com/thoughtbot/factory_bot/pull/1466
+module Gitlab
+  module FactoryBotStubPatch
+    def has_settable_id?(result_instance)
+      result_instance.class.respond_to?(:primary_key) &&
+        result_instance.class.primary_key
+    end
+  end
+end
+
+FactoryBot::Strategy::Stub.prepend(Gitlab::FactoryBotStubPatch)