Cross-cutting physics tests

Some physics properties are not specific to one module — they are contracts across modules: that any profile pairs with any DF and still virializes, that the units policy holds end-to-end, that gradients flow through the whole pipeline. progenax does not carry a dedicated tests/validation/test_cross_cutting.py; instead these cross-cutting properties are covered indirectly by the unit and integration suites listed below. This page documents which property each suite enforces, so the cross-cutting coverage is auditable rather than assumed.

What is covered, and where¶

The profile × DF virial contract¶

The defining cross-cutting check is that any spatial profile pairs with any velocity DF (protocol-based composition), and a matched pair sits at virial equilibrium with no external rescale. How the suite covers this:

• Matched pairs (Plummer⊗Plummer at the same $r_h$, King⊗King at the same $W_0$, EFF⊗EFF) recover $Q = T/|V| \approx 0.5$ to within finite-$N$ Poisson noise ($\sim 5\times10^{-3}$ at $N = 10^4$) — the unscaled DF is a true equilibrium. The matched-pair $Q$ is asserted in the validation-tier physics suites (test_plummer_physics.py, test_king_physics.py, test_eff_physics.py); the builder/cluster suites assert the composition (that any profile pairs with any DF and the matched DF is constructed).

• Mismatched pairs (e.g. Plummer positions at $r_h=1$ with Plummer velocities built for $r_h=2$) are expected to depart from 0.5, because the velocities no longer balance the potential they sit in. This physical asymmetry is what makes the matched-pair equilibrium a real result rather than an imposed one. (This is the rationale for the matched-pair checks, not a separately-asserted directional test.)

The per-model virial rows on the module validation pages (Plummer equilibrium, King profile validation, EFF profile validation) carry the measured numbers and tolerances; this page records that the composition across profile/DF combinations is exercised, not just the diagonal matched cases.

How to run¶

pytest tests/unit/test_builders.py -v
pytest tests/integration/test_units_through_pipeline.py -v
pytest tests/integration/test_jax_compatibility.py -v
pytest tests/integration/test_end_to_end.py -v

References¶

The per-module measured values live on the per-module validation pages (Plummer equilibrium, King profile validation, …); the three-tier methodology and tolerance conventions are at Validation methodology; the end-to-end gradient registry is at Differentiability gradient audit. This page maps the interaction contracts onto the suites that enforce them.