Hai TDD

For Chinese readers, see SKILL.zh_CN.md. The English SKILL.md is the execution source of truth.

Overview

Drive development with tests: write a failing test first, confirm it fails for the right reason, write the smallest implementation that passes, then refactor while keeping tests green. This is not "add tests at the end" — TDD defines behavior before implementation.

Core Principle

Red, then green, then refactor.

Do not write production code before a failing test. A test that never failed first has not proven it constrains the target behavior — so the RED failure is the evidence, not a formality. If implementation already exists without a test, do not call the process TDD; either label it as tests-after or return to a test-first path.

Skip or ask first when

The skill is already triggered; the open decision is whether TDD fits this change. Pause and confirm with the user when: