# Tdd

> Use when implementing any feature or bugfix. Enforces RED-GREEN-REFACTOR cycle with test-first approach.

- Skill: `voidful/tdd` (Agent Skill)
- Install (CLI): `npx skillmds@latest add voidful/tdd`
- Raw SKILL.md: https://api.skillmd.com/api/skills/voidful/tdd/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: Apache-2.0
- Author: voidful (https://skillmd.com/u/voidful)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/voidful/tdd

---


# Test-Driven Development (TDD)

## The Iron Law

```
NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST
```

Write code before the test? Delete it. Start over.

## The Cycle

1. **RED** — Write a test that fails. Run it. Confirm it fails for the right reason.
2. **GREEN** — Write the minimum code to make the test pass. Nothing more.
3. **REFACTOR** — Clean up. Both test and production code. Tests must still pass.

## In the Aixlarity Codebase

```bash
# Run a specific test
cargo test -p aixlarity-core test_name

# Run all tests
cargo test

# Run with output
cargo test -- --nocapture
```

## What Counts as "Minimum Code"

- If the test expects a return value, hardcode it first. Then generalize.
- If the test expects an error, return the error. Do not add error handling for cases no test covers yet.
- Resist the urge to "finish" the function. Let the next test drive the next behavior.

## When to Skip (Ask the User First)

- Throwaway prototypes that will be deleted within the session.
- Generated code (e.g., provider adapter boilerplate).
- Configuration files.