self-made solution

var Select = function (){};

Select.prototype.launch = function (cstring,fn){
                client = new pg.Client(cstring);
                client.connect(function(err){
                        if (err) return fn(err);
                });
                client.query("SELECT * FROM uuid_audit_table;",function(err,result){
                        if (err) return fn(err);
                        if (result.rows[0]){
                                return fn(null, result.rows[0]);
                        } else {
                                return fn(null,"");
                        }
                });

};

### then called inside topic this way:

                'we try to make a select': {
                        topic: function () {
                                var select = new Select;
                                select.launch(connString,this.callback);
                        },
                        'we get some data': function(topic) {
                                //console.log(topic);
                                assert.isNotNull(topic[1]);
                                client.end();
                        },
                        'and no error': function(topic){
                                assert.isUndefined(topic[0]);
                                client.end();
                        }