Testing Guide

CuBIE uses pytest with several custom markers and conventions.

Running Tests

# Full suite (requires CUDA GPU)
python -m pytest

# CPU-only tests (CUDASIM mode)
export NUMBA_ENABLE_CUDASIM=1
python -m pytest -m "not nocudasim"

# Specific module
python -m pytest tests/integrators/

# Specific test pattern
python -m pytest -k test_solver

Test Markers

nocudasim

Test requires a real GPU; skip in CUDASIM mode.

slow

Long-running test; useful with -m "not slow" for quick iterations.

sim_only

Test only runs in CUDASIM mode.

specific_algos

Test targets a specific algorithm and may be skipped in broad sweeps.

CUDASIM Mode

Setting NUMBA_ENABLE_CUDASIM=1 before import runs cubie in a simulated CUDA environment on the CPU. CI pipelines without GPUs use this mode. CUDASIM is single-threaded and much slower than GPU execution, so keep CUDASIM- compatible tests lightweight.

Fixture Patterns

tests/conftest.py provides shared fixtures for ODE systems, solver instances, and common parameter sets. Prefer using these fixtures over constructing test objects manually.

Key fixtures include pre-built ODE systems (Lotka–Volterra, van der Pol, linear test systems) and solver factories parameterised by algorithm.

Philosophy

• Failing tests are good. Tests should assert intended behaviour. If a test fails, fix the code, not the test (unless the test itself is wrong).

• Prefer real objects over mocks. Use actual CuBIE objects and real (small) ODE systems. Never patch is_device checks or CUDA availability.

• Never mark tests ``xfail`` or use importorskip to hide failures.