#include <mongoc/mongoc.h>

int
main (int argc, char *argv[])
{
   mongoc_client_t *client = NULL;
   mongoc_client_session_t *session = NULL;
   mongoc_session_opt_t *session_opts = NULL;
   mongoc_transaction_opt_t *default_txn_opts = NULL;
   bson_error_t error;
   const mongoc_session_opt_t* returned_session_opts = NULL;
   const mongoc_transaction_opt_t* returned_transaction_opts = NULL;

   mongoc_init ();

   client = mongoc_client_new ("mongodb://localhost/?w=0");
   /* construct session options and set an empty default transaction opts. */
   session_opts = mongoc_session_opts_new ();
   default_txn_opts = mongoc_transaction_opts_new ();
   mongoc_session_opts_set_default_transaction_opts (session_opts, default_txn_opts);
   session = mongoc_client_start_session (client, session_opts, &error);

   /* the default options should be inherited from the client but aren't */
   returned_session_opts = mongoc_client_session_get_opts (session);
   returned_transaction_opts = mongoc_session_opts_get_default_transaction_opts (returned_session_opts);
   BSON_ASSERT (mongoc_transaction_opts_get_write_concern (returned_transaction_opts) == NULL);
   /* transactions without an explicit write concern use NULL for the write concern. */

   mongoc_cleanup ();
   return 0;
}