Fix a bug in how we handle serialization errors

This commit fixes a bug in how we handle serialization errors with the
postgres backend and transactions. It turns out that we never update the
transaction manager state for `batch_execute` calls, which in turn are
used for executing the transaction SQL itself. That could lead to
situations in which we don't roll back the transaction, but in which we should
have done that.

Fixes #241

Author: weiznich

src/pg/mod.rs

@@ -146,7 +146,12 @@ impl SimpleAsyncConnection for AsyncPgConnection {
             .batch_execute(query)
             .map_err(ErrorHelper)
             .map_err(Into::into);
+
         let r = drive_future(connection_future, batch_execute).await;
+        let r = {
+            let mut transaction_manager = self.transaction_state.lock().await;
+            update_transaction_manager_status(r, &mut transaction_manager)
+        };
         self.record_instrumentation(InstrumentationEvent::finish_query(
             &StrQueryHelper::new(query),
             r.as_ref().err(),

src/transaction_manager.rs

@@ -381,12 +381,8 @@ where
                     ..
                 }) = conn.transaction_state().status
                 {
-                    match Self::critical_transaction_block(
-                        &is_broken,
-                        Self::rollback_transaction(conn),
-                    )
-                    .await
-                    {
+                    // rollback_transaction handles the critical block internally on its own
+                    match Self::rollback_transaction(conn).await {
                         Ok(()) => {}
                         Err(rollback_error) => {
                             conn.transaction_state().status.set_in_error();

tests/lib.rs

@@ -11,6 +11,7 @@ mod instrumentation;
 mod pooling;
 #[cfg(feature = "async-connection-wrapper")]
 mod sync_wrapper;
+mod transactions;
 mod type_check;
 
 async fn transaction_test<C: AsyncConnection<Backend = TestBackend>>(