Continuous Integration for Physics Code
The software practice of testing every change automatically, applied to scientific code so physics results stay correct as the code evolves.
Borrowing from software
In software engineering, continuous integration runs an automated test suite on every change so bugs are caught the moment they are introduced. Physics codes benefit from the same discipline, because a subtle change can break a result without breaking the program.
What a physics test suite contains
- Unit tests on individual functions and numerical kernels.
- Regression tests that pin key results to known values.
- Benchmark problems with analytic or reference solutions.
- Cross-checks between independent methods.
Why physics is harder to test
Physics outputs are often floating-point numbers that legitimately vary slightly across hardware and compilers, so tests use tolerances rather than exact matches, connecting to the two tiers in automated verification. Choosing the right tolerance is itself part of the science.
Applied at Kronos
Every change to the codes behind the Hyperion breeder and the burner triggers the suite. If a change moves the tritium breeding ratio, the design point, or a published figure, the suite catches it before the change lands, protecting the analysis record.
Beyond correctness
The same pipeline can check performance, flagging when a change makes a simulation slower, which matters for HPC efficiency. Correctness and speed are both guarded.
Culture
Continuous integration turns reproducibility from a heroic effort into routine practice, which is what lets a small team maintain a large, trustworthy codebase.