Tests

pixi run test     # tests/test_tandem.py and tests/test_conformance.py

Suite

tests/test_conformance.py reads tests/conformance, copies of the spec's conformance/*.json at commit 2a4bd08, and checks every item of the spec's conformance/CHECKLIST.md at 2a4bd08, on the native fills and on the XLA path:

• every bounded, normal, exponential and weighted choice case, values and end positions, whole, cut at elements 1, 7, 20, 21 and n - 1 (2, 8, 20 and the last even element for float32 normals), and one element at a time,
• the scalar bounded cases, by Lemire's loop over the port's plain draws,
• the fallback index of rejected and missed draws, the width that follows the range, the empty fills, odd n and the pairs of the float32 normals,
• the choice tables, rejected weights and choice under jit,
• the SHA-256 of the stream dumps and of the port's fills of them, and of the normal and exponential dumps,
• complex draws across a block, random access across rows and chunks, a draw at 2^63 - 1, and fills that would reach 2^64.

tests/test_tandem.py:

• checks every vector of the specification (tests/vectors.json),
• checks that a bounded fill cut at any element equals the whole fill and that int32 and int64 agree for a small range,
• checks split, fork and sub against fixed values from the C reference (tests/cross_port.json),
• checks the K = 8 variant, uniform and the bool and complex stream dtypes against the dumps,
• compares positioned reads and jax.random.bits with reference stream dumps in tests/data,
• checks the ziggurat tables against the spec file's SHA-256,
• checks that the XLA path's float64 normals keep their values when the misses run in batches of one or three, or finish on a gathered set of one or four,
• checks fork children at traced positions, and split children for indices up to 2^64 - 1 against a direct evaluation of F,
• checks normal moments to fourth order and a KS test on 10^7 draws, and chi-square uniformity of bounded integers at a range that rejects a quarter of the draws,
• and runs the key implementation under jit and vmap.

On a CUDA device with the extension, the whole suite runs on the kernels, and three more tests check that the kernels equal the XLA path on the CPU device for every fill at odd, unaligned and 2^33-bit starts and over many thread blocks, that a vmap batch equals its rows, and that a GPU lowering calls the kernels.

With the CPU extension, the whole suite runs on the tandem-c fills, and four more tests check that the fills equal the XLA path for every fill at odd and 2^33-bit starts, at chunk lengths 1 and 32 and at sizes that split over the thread pool, that the float32 normals equal tandem-c's pairs bit for bit, that a vmap batch equals its rows, and that a CPU lowering calls the fills and does not without the extension.

Fixtures

• tests/vectors.json and tests/conformance/*.json are copies of the spec repository's files, with a drift check in CI.
• tests/cross_port.json is written by tools/gen_split_fixture.c.

CI

• CI runs the suite on Linux and macOS, with Python 3.11 and 3.14, with and without the CPU extension.
• A separate job checks that tests/vectors.json equals the spec repository's vectors.json and tests/conformance its conformance directory at commit 2a4bd08.