Various studies have shown that the later in a project errors are found, the more it costs to fix them. The Continuous Integration (CI) approach of software development adopted by LArSoft can save time by finding errors earlier in the process. As Lynn Garren noted, “Using CI allows you to test your code in the complete LArSoft environment independent of other people, which can save you time.” Another important benefit is noted by Gianluca Petrillo, “By using the CI system, I gain confidence that my code changes will not break other people’s work since the tests in the CI system will notify me if something went awry.”
The LArSoft Continuous Integration system is the set of tools, applications and machines that allows users to specify and automate the execution of tests of LArSoft and experiment software. Tests are configured via text files in the various repositories and are launched in response to an http trigger initiated manually by a user or automatically on every git push command to the develop branch of the central repositories. Arguments in the trigger specify run-time configuration options such as the base release to use, the branch within each repository to build (the develop branch by default), and the test “suite” to run, where each suite is a workflow of tests specified in the configuration files. Prior to each test, the new code is built against the base release. The CI system reports status, progress, test results, test logs, etc. to a database and notifies users with a summary of results via email. A web application queries the database to display a summary of test results with drill-down links to detailed information.
As Erica Snider said, “People focus on the testing needed for their particular experiment. One benefit of our CI system is that, every time a change is made, it automatically tests the common code against all of the experiment repositories, then runs the test suites defined by each of the experiments. This allows us to catch interoperability problems within minutes after they are committed.”
There have been a number of updates to CI in recent months aimed at making the system easier and more intuitive for users, so please try it.
You can find more information about CI at http://larsoft.org/continuous-integration/ with detailed instructions on how to run jobs at: https://cdcvs.fnal.gov/redmine/projects/lar_ci/wiki