Validation
==========

``at-py`` uses three layers of validation:

* fast unit tests for parser, formatter, MAT, and client wiring behavior;
* executable documentation examples for user-facing snippets;
* runner-backed integration tests for end-to-end workflows through
  ``at-runner``.

Runner-Backed Corpus
--------------------

The integration corpus intentionally starts small and reproducible. It should
grow by adding complete AT cases with checked parser outputs rather than broad
fixture dumps.

Current runner-backed cases:

.. list-table::
   :header-rows: 1
   :widths: 25 35 40

   * - Case
     - Runner check
     - Parser check
   * - KRAKEN Pekeris
     - ``ATClient.kraken`` exits successfully through ``at-runner``.
     - The generated mode file is parsed with ``read_modes_bin`` and checked for
       non-empty mode count, positive wavenumbers, and receiver/source grid
       dimensions.

Adding Cases
------------

When adding a validation case:

* keep the input text small enough to review;
* check at least one parsed output rather than only process exit status;
* prefer stable shape, count, and monotonicity assertions over fragile exact
  floating-point snapshots;
* mark runner-backed tests with ``@pytest.mark.integration`` so local unit runs
  remain fast.