Create allow_next_instance_of spec helper

doc/development/gotchas.md

@@ -106,7 +106,7 @@ end
        Using `any_instance` to stub a method (elasticsearch_indexing) that has been defined on a prepended module (EE::ApplicationSetting) is not supported.
   ```
 
-### Alternative: `expect_next_instance_of`
+### Alternative: `expect_next_instance_of` or `allow_next_instance_of`
 
 Instead of writing:
 

spec/spec_helper.rb

@@ -90,6 +90,7 @@ RSpec.configure do |config|
   config.include StubFeatureFlags
   config.include StubGitlabCalls
   config.include StubGitlabData
+  config.include AllowNextInstanceOf
   config.include ExpectNextInstanceOf
   config.include TestEnv
   config.include Devise::Test::ControllerHelpers, type: :controller

spec/support/helpers/allow_next_instance_of.rb

+# frozen_string_literal: true
+
+module AllowNextInstanceOf
+  def allow_next_instance_of(klass, *new_args)
+    receive_new = receive(:new)
+    receive_new.with(*new_args) if new_args.any?
+
+    allow(klass).to receive_new
+      .and_wrap_original do |method, *original_args|
+        method.call(*original_args).tap do |instance|
+          yield(instance)
+        end
+      end
+  end
+end