Purpose
-------
Unit tests for ``oct.git.conventional`` (Phase 4D — G-D1, G-D2, G-D5).
Responsibilities
----------------
- Verify Conventional Commits parsing (type, scope, subject, body, footer).
- Verify commit message validation rules.
- Verify validation error formatting.
- Verify diagnostics impact analysis on diffs.
Diagnostics
-----------
Domain: GIT-TESTS
Levels:
L2 — test lifecycle
L3 — assertion details
L4 — deep tracing
Contracts
---------
- All tests are pure unit tests (no filesystem or git needed).