Python testing defaults

Personal, agent-maintained Python projects. Split out of python-conventions on 2026-08-31, which keeps the design and style defaults; this skill owns the test suite. Nothing here is tool config — pytest's own configuration lives with the repo's quality tooling, not here.

Each entry says whether it's overriding your own default instinct or just confirming one. A capable model already parametrizes value matrices and reaches for tmp_path unprompted. This skill exists for the places a model left alone drifts — inlining the same arrange block into every test rather than promoting it to a fixture, and reaching for a mock where the suite could own the real thing.

Testing conventions