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(); }