In this paper, we present an all-IP heterogeneous wireless testbed for radio access technologies (RAT) selection and end-to-end (e2e) quality of service (QoS) evaluation. Presented testbed includes three different radio access networks (RANs): UTRAN, GERAN, and WLAN; and the core network (CN) based on DiffServ technology and multiprotocol label switching (MPLS). As an example two RAT selection algorithms implemented in the testbed, network-controlled cell-breathing (NCCB) and fittingness factor are described and analyzed in more details. The paper provides also simple case study that validates and compares both mentioned algorithms in a basic heterogeneous environment using the presented testbed.