Tests

pixi run test
pixi run -e cross test    # also builds tandem-numpy from its repository and compares

Suite

tests/test_tandem.py checks:

• every vector of the specification, including T and F of the Metal source on the vector states;
• the stream dumps of tandem-c in tests/data for uint8, uint32, uint64, float16, float32, float64 and K = 8, from position 0 and from unaligned starts;
• blocks at rows past 2**50, where the chunk counter needs 64 bits, against a host evaluation of F and T for K = 1, 8, 32 and 65536;
• split, fork and purpose children for indices up to 2**64 - 1 against the C reference (tests/cross_port.json);
• normal fills from even and odd draws, over many groups and every end lane, against Box-Muller applied to the uniform fill;
• that a bounded fill cut at any element equals the whole fill, rejections included;
• raw moments 1 to 4 and the Kolmogorov-Smirnov distance of 10^7 normals and 10^7 exponentials;
• that tandem.metal is tandem-metal's file, by its SHA-256;
• with tandem-numpy installed, words, uniforms, bounded integers, normals and exponentials against its C fills, bit for bit.

tests/test_conformance.py reads the spec's conformance files and checks the items of its conformance/CHECKLIST.md at 2a4bd08:

• every bounded, Float32 normal, Float32 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 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 draws, the width that follows the range, the empty fills, odd n and the normal pairs;
• the choice tables and rejected weights;
• the SHA-256 of the stream dumps and of the port's fills of them;
• reads across blocks, rows and chunks, a draw at 2^63 - 1, and fills that would reach 2^64.

Metal has no double type, so the Float64 cases and the long outputs of tandem-c's dump tools are not run, and MLX has no complex draws.

Fixtures

• tests/vectors.json is a copy of the spec repository's file.
• tests/conformance holds the spec's conformance/*.json at commit 2a4bd08.
• tests/data holds the stream dumps of tandem-c.
• tests/cross_port.json comes from tandem-jax.

CI

CI runs pytest on macos-15 with Python 3.13 and on macos-latest with Python 3.14, with tandem-numpy built from source for the cross-check. A drift check fails when tests/vectors.json differs from the spec repository's file, or tests/conformance from the spec's conformance directory at 2a4bd08.