Tests

pixi run test         # CPU tests
pixi run test-gpu     # on a host with a supported GPU

Suite

• The specification vectors in tests/vectors_data.mojo, generated from the spec's vectors.json.
• Long fills, scalar draws and random access against the dumps in tests/data, copied from tandem-c/tests/data.
• Fills against the scalar draws at offsets and lengths that cut rows and chunks.
• The conformance files of the spec: bounded integers, normals, exponentials and weighted choice, with the stream and dump hashes.
• GPU fills against the CPU fills.

Files

• tests/test_vectors.mojo checks every vector of the specification. tests/vectors_data.mojo is generated from the spec repository's vectors.json by tools/gen_vectors.py.
• tests/test_dumps.mojo compares long fills, scalar draws and random access with the reference stream dumps in tests/data, complex fills included. The dumps are copies of tandem-c/tests/data.
• tests/test_tandem.mojo covers scalar draws of every width, alignment, random access, set_position, chunk lengths, split, sub and fork.
• tests/test_fills.mojo compares every fill with the scalar draws of its type, at chunk lengths, offsets and lengths that cut rows and chunks, and checks the position afterwards.
• tests/test_conformance.mojo reads the byte copies of the spec's conformance/*.json in tests/conformance through tests/conformance.mojo, and demonstrates every item of the spec's conformance/CHECKLIST.md at 2a4bd08. Every case of the bounded, normal, exponential and weighted choice files runs as a fill, as scalar draws and cut at elements 1, 7, 20, 21 and n - 1 (Float32 normals at 2, 8, 20 and the largest even element below n), bit for bit with the end position, including the f32 normals. It builds the choice tables and compares S, cut and alias, and checks the stream and dump hashes of hashes.json by SHA-256 and FNV-1a from the key. It checks the global draw index of the fallback, the width of the bounded draws, empty fills, the pair rule and odd n of the f32 normals, rejected choice weights and the choice law, random access, a complex draw across a block, and the position bounds.
• tests/test_derived.mojo checks the bounded fills against their definition at every length that cuts a SIMD block, long f64 normal, bounded and exponential fills cut into chunks, the f32 normals against the exact formula, the logarithm and the f32 series against libm, and the moments of the normals and the moments and KS distance of 1e7 exponentials.
• tests/test_gpu.mojo compares the GPU fills with the CPU fills over chunk lengths and row ranges, and with the dump.

Fixtures

tests/vectors_data.mojo is generated from the spec repository's vectors.json by tools/gen_vectors.py. The dumps in tests/data are copies of tandem-c/tests/data. tests/conformance/*.json are byte copies of tandem-spec 2a4bd08 conformance/*.json. tools/gen_zig_tables.py writes zig_tables.mojo from the spec's tables/normal_f64_zig1024.json. CI checks all of them. mojo run -I . tools/dump_normals.mojo out.bin writes the bytes of tandem-c's tools/dump_normals.c, SHA-256 700ec4d2f4d6b82aaa56c6eff18a4e5919585fdbd093988773383d580ea610d1.

CI

• CI runs pixi run test on Ubuntu. CI does not run the GPU tests.
• One job checks that the vector data is current, and one that the dumps and the conformance files are.