Allow postgresql enum_test to be run in random order.

Creating and dropping similar tables within the same connection causes postgresql to look up old values in the cache of tables which have already been dropped.

activerecord/test/cases/adapters/postgresql/domain_test.rb

@@ -1,18 +1,17 @@
 # -*- coding: utf-8 -*-
 require "cases/helper"
+require 'support/postgresql_helper'
 require 'active_record/base'
 require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlDomainTest < ActiveRecord::TestCase
+  include PostgresqlHelper
+
   class PostgresqlDomain < ActiveRecord::Base
     self.table_name = "postgresql_domains"
   end
 
   def setup
-    # reset connection to bust all cached statement plans
-    connection_spec = ActiveRecord::Base.remove_connection
-    ActiveRecord::Base.establish_connection(connection_spec)
-
     @connection = ActiveRecord::Base.connection
     @connection.transaction do
       @connection.execute "CREATE DOMAIN custom_money as numeric(8,2)"
@@ -28,6 +27,7 @@ def setup
   teardown do
     @connection.execute 'DROP TABLE IF EXISTS postgresql_domains'
     @connection.execute 'DROP DOMAIN IF EXISTS custom_money'
+    reset_pg_session
   end
 
   def test_column

activerecord/test/cases/adapters/postgresql/enum_test.rb

@@ -1,18 +1,16 @@
 # -*- coding: utf-8 -*-
 require "cases/helper"
+require 'support/postgresql_helper'
 require 'active_record/base'
 require 'active_record/connection_adapters/postgresql_adapter'
 
 class PostgresqlEnumTest < ActiveRecord::TestCase
+  include PostgresqlHelper
+
   class PostgresqlEnum < ActiveRecord::Base
     self.table_name = "postgresql_enums"
   end
 
-  teardown do
-    @connection.execute 'DROP TABLE IF EXISTS postgresql_enums'
-    @connection.execute 'DROP TYPE IF EXISTS mood'
-  end
-
   def setup
     @connection = ActiveRecord::Base.connection
     @connection.transaction do
@@ -27,6 +25,12 @@ def setup
     @connection.send(:reload_type_map)
   end
 
+  teardown do
+    @connection.execute 'DROP TABLE IF EXISTS postgresql_enums'
+    @connection.execute 'DROP TYPE IF EXISTS mood'
+    reset_pg_session
+  end
+
   def test_column
     column = PostgresqlEnum.columns_hash["current_mood"]
     assert_equal :enum, column.type

activerecord/test/support/postgresql_helper.rb

@@ -0,0 +1,8 @@
+module PostgresqlHelper
+  # Make sure to drop all cached query plans to prevent invalid reference errors like:
+  #  cache lookup failed for type XYZ
+  def reset_pg_session
+    original_connection = ActiveRecord::Base.remove_connection
+    ActiveRecord::Base.establish_connection(original_connection)
+  end
+end