As Spatial Data Infrastructures (SDI) and prominently INSPIRE (Infrastructure for Spatial Information in Europe) lead to operational services that are getting involved in day-to-day business processes tools, measurements to test, assure, monitor and finally also certify the services’ fitness-for-use become urgently needed. The abstract first analysis and categorises types of testing activities in SDI. Based on this analysis an organisational and conceptual frame developed in the GIGAS (GEOSS, INSPIRE, GMES - An Action in Support) project for SDI testbeds is presented. The proposed three-folded approach is based on a Meta SDI Testbed (a knowledge base about ongoing testbeds), a Persistent Interoperability Testbed (showing the maturation from research to pre-operational applications) and a Persistent Test Harness (for compliance checking). The expected benefits for the SDI community are outlined.