refactor schema migration table creation to the schema migration model

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

@@ -414,15 +414,7 @@ def dump_schema_information #:nodoc:
       # Should not be called normally, but this operation is non-destructive.
       # The migrations module handles this automatically.
       def initialize_schema_migrations_table
-        sm_table = ActiveRecord::Migrator.schema_migrations_table_name
-
-        unless table_exists?(sm_table)
-          create_table(sm_table, :id => false) do |schema_migrations_table|
-            schema_migrations_table.column :version, :string, :null => false
-          end
-          add_index sm_table, :version, :unique => true,
-            :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"
-        end
+        ActiveRecord::SchemaMigration.create_table
       end
 
       def assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths)

activerecord/lib/active_record/migration.rb

@@ -669,7 +669,7 @@ def initialize(direction, migrations, target_version = nil)
 
       validate(@migrations)
 
-      Base.connection.initialize_schema_migrations_table
+      ActiveRecord::SchemaMigration.create_table
     end
 
     def current_version

activerecord/lib/active_record/schema_migration.rb

@@ -8,6 +8,24 @@ def self.table_name
       Base.table_name_prefix + 'schema_migrations' + Base.table_name_suffix
     end
 
+    def self.create_table
+      unless connection.table_exists?(table_name)
+        connection.create_table(table_name, :id => false) do |t|
+          t.column :version, :string, :null => false
+        end
+        connection.add_index table_name, :version, :unique => true,
+          :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"
+      end
+    end
+
+    def self.drop_table
+      if connection.table_exists?(table_name)
+        connection.remove_index table_name, :version, :unique => true,
+          :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"
+        connection.drop_table(table_name)
+      end
+    end
+
     def version
       super.to_i
     end

activerecord/test/cases/migrator_test.rb

@@ -19,6 +19,7 @@ def down; @went_down = true; end
 
     def setup
       super
+      ActiveRecord::SchemaMigration.create_table
       ActiveRecord::SchemaMigration.delete_all rescue nil
     end