Software Validation Infrastructure for the ATLAS Trigger

The ATLAS trigger system is responsible for selecting the interesting collision events delivered by the Large Hadron Collider (LHC). The ATLAS trigger will need to achieve a ~10^-7 rejection factor against random proton-proton collisions, and still be able to efficiently select interesting events. After a first processing level based on hardware, the final event selection is based on custom software running on two CPU farms, containing around two thousand multi-core machines. This is known as the high-level trigger. Running the trigger online during long periods demands very high quality software. It must be fast, performant, and essentially bug-free. With more than 100 contributors and around 250 different packages, a thorough validation of the HLT software is essential. This relies on a variety of unit and integration tests as well as on software metrics, and uses both in-house and open source software. This presentation presents the existing infrastructure used for validating the high-level trigger software, as well as plans for its future development.