Agile software development methods such as eXtreme Programming have brought renewed attention to testing during the software development process, both as a quality assurance method and as a form of live documentation. It is for this reason that a software system?s testsuite is an ideal starting point for gaining knowledge about its inner workings. In this paper, we propose to use sequence diagrams to visualize information that is dynamically obtained from testsuites. We employ abstraction techniques such as constructor hiding and stack depth limitation to make the diagrams more scalable. We use JPACMAN as a case study to validate our results by consulting with domain experts, and use their feedback to fine-tune our techniques.