Use initializer to configure tenant mode

config/environments/test.rb

@@ -67,4 +67,7 @@ Rails.application.configure do
 
   # Load test helpers
   config.autoload_paths += %w[ test/test_helpers ]
+
+  # Enable multi-tenant mode for tests
+  config.x.multi_tenant = true
 end

config/initializers/multi_tenant.rb

@@ -0,0 +1,3 @@
+Rails.application.config.after_initialize do
+  Account.multi_tenant = ENV["MULTI_TENANT"] == "true" || Rails.configuration.x.multi_tenant == true
+end