anchor.diff:       transaction_should_commit_on_success,
        transaction_should_abort_on_exception,
        transaction_should_abort_on_user_abort,
  +     transaction_error_should_return_error, 
        update_should_save_value_if_successful,
        update_should_accept_args_for_fun,
        port_should_tune_transaction_timeouts,
  
positive.code: 
      {error, transaction_aborted} = bdberl:transaction(F),
      not_found = bdberl:get(Db, mykey).
  
  update_should_save_value_if_successful(Config) ->
      Db = ?config(db, Config),
  
negative.code:     ok = bdberl:close(?config(db, Config)),
      ok = bdberl:delete_database("api_test.db").
  
  open_should_create_database_if_none_exists(Config) ->
      DbName = filename:join([?config(priv_dir, Config), "api_test.db"]),
      true = filelib:is_file(DbName).
  