use migration helpers in spec

lib/active_record/aux_table.rb

@@ -76,18 +76,19 @@ module ActiveRecord
       end
 
       # Main DSL method for defining auxiliary tables
-      sig { params(table_name: T.any(String, Symbol)).returns(AuxTableConfig) }
-      def aux_table(table_name)
-        table_name = table_name.to_sym
+      sig { params(aux_name: T.any(String, Symbol)).returns(AuxTableConfig) }
+      def aux_table(aux_name)
+        base_table = self.table_name
+        aux_table_name = :"#{base_table}_#{aux_name}_aux"
 
-        if aux_table_configurations.key?(table_name)
+        if aux_table_configurations.key?(aux_table_name)
           Kernel.raise ArgumentError,
-                       "Auxiliary table '#{table_name}' is already defined"
+                       "Auxiliary '#{aux_name}' (table '#{aux_table_name}') is already defined"
         end
 
-        aux_table_configurations[table_name] = config =
-          generate_aux_model_class(table_name)
-        setup_schema_loading_hook(table_name)
+        aux_table_configurations[aux_table_name] = config =
+          generate_aux_model_class(aux_table_name)
+        setup_schema_loading_hook(aux_table_name)
         setup_auto_join_queries(config)
 
         config