| name | test-unit |
| description | Phase 7 unit testing via test-driven tracer bullets — write one behavior test through the public interface, make it pass, repeat. Always required. Use when: writing new logic, adding a unit-level behavior, the test-strategy selects unit (always), red-green-refactor. |
One-Liner
Drive each unit with a test that describes behavior through the public interface — one tracer
bullet at a time, never write all tests bulk-first.
Delegate craft depth to the experts. For test architecture/mocking/coverage load
test-master; for strict red-green cadence load
tdd-workflow (see
../../resources/expert-skills-map.md).
Core Philosophy
Tests verify behavior, not implementation: code can be rewritten and good tests survive.
Anti-pattern — horizontal slicing: writing all tests first, then all implementation, produces
tests against imagined behavior that fail on contact with reality. Use vertical slices: one
test → minimal implementation → repeat, each cycle using real learning from the last.
Workflow
Phase 1 — Plan
List the behaviors to cover (acceptance criteria + edge cases: null/empty, boundary, error paths),
prioritized. Confirm the public interface (signatures/props/endpoint).
Gate: behavior list agreed; no test written yet.
Phase 2 — Tracer bullet
Write one test that (a) calls a public interface, (b) asserts observable output, (c) reads like a
spec ("given X, when Y, then Z"). Run it → confirm it fails for the right reason → write the
minimal code → run → green.
Gate: test green; it would survive a full rewrite of the implementation.
Phase 3 — Incremental loop
Repeat Phase 2 per behavior in priority order. Keep tests deterministic (inject clock/network/random);
mock external collaborators; fast (ms).
Gate: all selected unit behaviors are green.
Examples (Bad vs Good)
assert svc._cache._store["k"] == 1
assert svc.get("k") == 1
Coverage
Cover every acceptance criterion plus the edge cases listed in Phase 1 (null/empty, boundary, error
paths). Branches with logic must be exercised — an untested error path is a coverage hole. Where the
project sets a coverage threshold, meet it; never lower the threshold to go green.
Run & record (REQUIRED format — the test-type-coverage-gate enforces a green verdict)
Run the project's unit command (npm test / pytest / go test ./...); record the verdict in
evidence ## Test as a verdict line with a count:
## Test
- unit: PASS — 42 tests, 0 failing (covers happy + null/empty/boundary/error paths)
A unit: line is mandatory (unit is always selected). The gate blocks harness verify if the
unit: verdict is FAIL / PENDING / TODO / SKIP rather than PASS. This command is the
task's unit: verification, executed by harness verify.
Gate: unit green is a prerequisite for the broader test types and verify.
(Methodology adapted from tdd-workflow, theNeoAI, MIT. Test types are selected by
check-test-strategy.)
