A regression testing tool ensure that new problems and unexpected behaviors will not be introduced to PMD project after fixing an issue and new rules work as expected. == Features/Problems: The diff report can be generated according to the base and patch branch of PMD on a list of standard projects (e.g. Spring Framework, Checkstyle, OpenJDK, etc.). Rule violations and code duplications are compared to report, which are new, removed or changed. While executing PMD, JDK Flight Recorder (jfr) is enabled and a recording is created. This allows to investigate performance and memory issues afterwards.