Prechelt, LutzSchmeisky, HolgerZieris, FranzTichy, MatthiasBodden, EricKuhrmann, MarcoWagner, StefanSteghöfer, Jan-Philipp2019-03-292019-03-292018978-3-88579-673-2https://dl.gi.de/handle/20.500.12116/21129This work was presented at the 38th International Conference on Software Engineering (2016). Context: While successful conventional software development regularly employs separate testing staff, there are successful agile teams with as well as without separate testers. Question: How does successful agile development work without separate testers? What are advantages and disadvantages? Method: A case study, based on Grounded Theory evaluation of interviews and direct observation of three agile teams; one having separate testers, two without. All teams perform long-term development of parts of e-business web portals. Results: Teams without testers use a "quality experience" work mode centered around a tight field-use feedback loop, driven by a feeling of responsibility, supported by test automation, resulting in frequent deployments. Conclusion: In the given domain, hand-overs to separate testers appear to hamper the feedback loop more than they contribute to quality, so working without testers is preferred. However, Quality Experience is achievable only with modular architectures and in suitable domains.enagile software developmentquality assuranceindustrial case studygrounded theoryText/Conference Paper1617-5468