Design and Implementation of a Test Tool for PSD2 Compliant Interfaces

The Revised Payment Services Directive (PSD2) forces retail banks to make customer accounts accessible to TPPs via standardized and secure”Access to Account” (XS2A) interfaces. Furthermore, banks have to ensure that these interfaces continuously meet functional and performance requirements, hence testing is very important. A known challenge in software testing is the design of test cases. While standardized specifications and derived test cases exist, the actual implementations of XS2A interfaces often deviate, leading to the need to adapt existing or create new test cases. We apply a design science approach, including five expert interviews, to iteratively generate a concept of a test tool that enables testing of several XS2A interface implementations with the same set of test cases. The concept makes use of files mapping deviations between the standardized specification and the implemented interfaces. We demonstrate the concept's feasibility by implementing a prototype and testing its functionality in a sandbox setting.