TDD

Loop

1. Red — write one failing check for the next behaviour slice.
2. Green — make the smallest implementation pass.
3. Refactor — simplify while the check stays green.
4. Repeat until the contract is covered.

Output

Name every phase: Red, Green, Refactor, Repeat. Finish with: Passing check, Normal command, Untestable (none or remaining edge).

Completion: every requested behavior has a passing check, the check ran in the repo's normal command, and any untestable edge is reported.

Test choice

Prefer the highest-level test that proves the behaviour without brittle setup. HTTP paths: request/response tests. Service/repository: integration tests when practical. Go: table-driven with testify/require if project uses it. Keep mocks at boundaries. Do not mock what you can run cheaply. One assert-style self-check suffices for tiny cases.