Superconducting undulators constitute an important element of the European XFEL facility development program. The application of SCU technology at European XFEL paves the way to potentially enable lasing above 50 keV, opening new frontiers in scientific research and offering unprecedented capabilities in high-energy applications. A total of six modules are foreseen. The Superconducting undulator PRE-SerieS mOdule (S-PRESSO) is the preseries module for the free-electron laser superconducting undulator afterburner. This article presents a comprehensive assessment of the S-PRESSO superconducting undulator mock-up's magnetic performance conducted at the Institute for Beam Physics and Technology of the Karlsruhe Institute of Technology. After a description of the experimental setup and the coil, the results of training and of the magnetic field measurements are presented. The results demonstrate a robust design of the mock-up, which achieved the short sample limit, a long lasting stability at nominal current tested for 8 h, and a straight trajectory below European XFEL requirements. The measured quality of the magnetic field is studied and compared with simulations using the geometric values measured at room temperature with a coordinate measuring machine. This analysis suggests areas for potential improvement in the manufacturing process.