pymc-testing
Installation
SKILL.md
PyMC Testing
PyMC provides testing utilities to speed up test suites by mocking MCMC sampling with prior predictive sampling. This is useful for checking model structure without running expensive inference.
Mock Sampling vs Real Sampling
| Aspect | Mock Sampling | Real Sampling |
|---|---|---|
| Speed | Fast (seconds) | Slow (minutes) |
| Use case | Model structure, downstream code | Posterior values, convergence |
| Output | prior, prior_predictive |
Full posterior, sample_stats, warmup groups |
| Divergences | Mocked (configurable) | Real diagnostics |
Use mocking when: Testing model specification, CI/CD pipelines, plotting code, API integration, serialization.
Use real sampling when: Checking posterior values, ESS/r_hat diagnostics, LOO-CV, model comparison. See pymc-modeling skill for real inference.