ICST 2019 is the 12th International Conference on Software Testing, Verification and Validation that took place in Xi’an, China on 22-27 April 2019. ICST 2019 featured keynote addresses from renowned academia and industry scientists, several tracks, including Research, Industry, Testing Tool and Poster Tracks, a PhD symposium, and a Tools Demo track, as well as numerous workshops and co-located events. All the submitted research papers went through a rigorous double-blind review process and acceptance was based on "quality, originality and relevance". The conference proceedings are expected to be submitted for publication in IEEE Xplore. Exactpro’s ClearTH Test Automation Framework for DLT-Based Post-Trade Systems demo was presented in the Demo Track on 24 April 2019.