After three successful editions in Barcelona 2022, Venice 2023 and Tallinn 2025, there will be a fourth IMTR workshop in 2026, again co-located with the IEEE European Test Symposium in Chania, Crete, on 28-29 May. The workshop considers interdisciplinary problems at the boundary between test methods and data science; it is supported by the Graduate School IMTR. Many PIs and PhD students attended the workshop.