Ensure adapater specific code is loaded on ActiveRecord::Base.establish_connection

activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb

@@ -211,6 +211,7 @@ def self.establish_connection(spec = nil)
           clear_active_connection_name
           @active_connection_name = name
           @@defined_connections[name] = spec
+          connection
         when Symbol, String
           if configuration = configurations[spec.to_s]
             establish_connection(configuration)