Acts tests and continuous integration

Modern software development techniques relies on automated tests and continuous integration platforms to ensure the functionality of a given software package. It verifies that existing behaviour remains unchanged when updating or optimizing its implementation and allows automated testing of new functionality.

Acts provides an extensive unit test suite that checks geometry and propagation functionality at the smallest unit level, e.g. a single geometric surface type. Tests are based on known solutions for simple cases or manual calculations for selected configuration. These tests can be run very fast and usually take less that a second. They allow fast iteration and verification for the developers.

In addition, we have started to provide larger integration tests that aim to test combinations of multiple Acts components. A typical example would be a full geometry propagation chain. It includes geometry description, geometry navigation, and particle propagation that all have to work together to allow efficient transport of particles through a tracking detector. The integration tests usually check for self-consistency or variations from previous known-good results for a large variety of inputs. They are expected to have a run time of the order of minutes and are intended to run as part of a merge request.

Acts employs the continuous integration platform provided by the CERN Gitlab installation. Within this platform each change pushed to the common repository is compiled with multiple build configurations. The build configuration are chosen to encompass all supported Linux distributions (Scientific Linux CERN 6, CERN CentOS 7), different compilers (GCC, CLang) and different LCG software releases starting from the minimum requirement (LCG93). Additional checks are performed to ensure consistent licensing and formatting. The available platforms were chosen to be consistent with typical setups available to users, e.g. on lxplus machines at CERN. Special care was taken to not require any additional software but the ones provided by the distributions themselves and the LCG releases with the versions that are provided. The continuous integration builds activate all optional components to avoid unintentional breakage due to deactivated components on a developers local copy. Together ensures consistent functionality and ease-of-use on all platforms and greatly reduces possible barriers for future users.