Be clearer about when transactions are reset by reconnection

This adds a very awkward test-private method that attempts to detect
whether a raw connection physically has a transaction open -- which is
quite Not Great, but this seems important to get right.

Author: matthewd

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -322,9 +322,9 @@ def reload_type_map # :nodoc:
       def reconnect!
         @lock.synchronize do
           @raw_connection.reset
+          super
           configure_connection
           reload_type_map
-          super
         rescue PG::ConnectionBad
           connect
         end

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -165,6 +165,9 @@ def active?
       end
 
       def reconnect!
+        unless @raw_connection.closed?
+          @raw_connection.rollback rescue nil
+        end
         super
         connect if @raw_connection.closed?
       end

activerecord/test/cases/adapter_test.rb

@@ -384,20 +384,50 @@ def setup
         assert_predicate @connection, :active?
       end
 
-      test "transaction state is reset after a reconnect" do
+      test "materialized transaction state is reset after a reconnect" do
         @connection.begin_transaction
         assert_predicate @connection, :transaction_open?
+        @connection.materialize_transactions
+        assert raw_transaction_open?(@connection)
         @connection.reconnect!
         assert_not_predicate @connection, :transaction_open?
+        assert_not raw_transaction_open?(@connection)
       end
 
-      test "transaction state is reset after a disconnect" do
+      test "materialized transaction state is reset after a disconnect" do
         @connection.begin_transaction
         assert_predicate @connection, :transaction_open?
+        @connection.materialize_transactions
+        assert raw_transaction_open?(@connection)
         @connection.disconnect!
         assert_not_predicate @connection, :transaction_open?
       ensure
         @connection.reconnect!
+        assert_not raw_transaction_open?(@connection)
+      end
+
+      test "unmaterialized transaction state is reset after a reconnect" do
+        @connection.begin_transaction
+        assert_predicate @connection, :transaction_open?
+        assert_not raw_transaction_open?(@connection)
+        @connection.reconnect!
+        assert_not_predicate @connection, :transaction_open?
+        assert_not raw_transaction_open?(@connection)
+        @connection.materialize_transactions
+        assert_not raw_transaction_open?(@connection)
+      end
+
+      test "unmaterialized transaction state is reset after a disconnect" do
+        @connection.begin_transaction
+        assert_predicate @connection, :transaction_open?
+        assert_not raw_transaction_open?(@connection)
+        @connection.disconnect!
+        assert_not_predicate @connection, :transaction_open?
+      ensure
+        @connection.reconnect!
+        assert_not raw_transaction_open?(@connection)
+        @connection.materialize_transactions
+        assert_not raw_transaction_open?(@connection)
       end
     end
 
@@ -489,6 +519,31 @@ def test_reset_table_with_non_integer_pk
     end
 
     private
+      def raw_transaction_open?(connection)
+        case connection.class::ADAPTER_NAME
+        when "PostgreSQL"
+          connection.instance_variable_get(:@raw_connection).transaction_status == ::PG::PQTRANS_INTRANS
+        when "Mysql2"
+          begin
+            connection.instance_variable_get(:@raw_connection).query("SAVEPOINT transaction_test")
+            connection.instance_variable_get(:@raw_connection).query("RELEASE SAVEPOINT transaction_test")
+
+            true
+          rescue
+            false
+          end
+        when "SQLite"
+          begin
+            connection.instance_variable_get(:@raw_connection).transaction { nil }
+            false
+          rescue
+            true
+          end
+        else
+          skip
+        end
+      end
+
       def reset_fixtures(*fixture_names)
         ActiveRecord::FixtureSet.reset_cache