The RET (Requirements Engineering and Testing) workshop series provides a meeting point for researchers and practitioners from the two separate fields of Requirements Engineering (RE) and Testing. The long term aim is to build a community and a body of knowledge within the intersection of RE and Testing, i.e., RET. The 4th workshop was co-located with the 25th International Requirements Engineering Conference (RE'17) in Lisbon, Portugal and attracted about 20 participants. In line with the previous workshop instances, RET 2017 o ered an interactive setting with a keynote, an invited talk, paper presentations, and a concluding hands-on exercise.