ATS (Automated Testing System) is a Python-based tool for automating the running of an application’s tests across a broad range of high-performance computers. ATS features include generating and comparing plot files, testing code correctness and performance with different software libraries and compiler configurations, and archiving metrics related to each test run. The tool is flexible enough for experts and non-experts alike. ATS Documentation is available, and more information about how LLNL uses ATS can be found on the Computing website.