test-first (the test-shaping technique)

The cycle — RED → GREEN → REFACTOR → COMMIT, its per-phase gates, the characterize-first rule, the bug-fix and refactor variants, the migration safety gate, and the recorded exceptions — lives in docs/graph/protocols/test-first.md, the one home for the workflow. This skill owns the craft of shaping each test the cycle asks for.

Test level selection

Pick the lowest level that exercises the behavior.

Level	Use when
Unit	Pure logic, transformations, parsers, validators.
Integration	Crossing an adapter (DB, file, network, SDK, model).
Contract	API endpoints, structured outputs, message schemas.
End-to-end	Critical flows — one or two per flow, no more.
Golden / snapshot	Deterministic transforms, prompts, renderers.
Property-based	Algorithms where the property is clearer than examples.
Evaluation	LLM/VLM behavior, with rubrics and pass thresholds.

Test shape

• The name names the contract. The spec §4 contract slug, transformed for the language's convention (test_submit_valid_form_returns_2xx, submitValidFormReturns2xx, …). The reviewer should be able to read the test names and reconstruct the spec.
• The body is Given/When/Then. Set up Given, perform When, assert Then.
• One outcome per test (or one assertion group about the same outcome). Many small tests beat one giant one.

Reference files

• docs/graph/protocols/test-first.md — the workflow this technique serves.
• docs/graph/templates/spec.template.md — where contracts live (§4) and test mapping is recorded (§10).
• docs/graph/agents/04-tester.md — the agent that owns the cycle.
• docs/graph/agents/02-implementer.md — the agent that writes GREEN.