Tdd

It never skips a VERIFY step -- a test that passes on first run proves nothing and must be investigated, not accepted.

TDD Skill

Write the test first. Watch it fail. Write minimal code to pass.

The Iron Law

No production code without a failing test first.

Every line of production code must be justified by a test that failed without it. No exceptions. No shortcuts. No "I'll test after."

Agent Workflow

1. DETECT  -> Identify stack, test framework, existing test patterns
2. RED     -> Write ONE failing test for the next behavior
3. VERIFY  -> Run test, confirm it fails for the EXPECTED reason
   IF the test fails for a DIFFERENT reason (syntax error, wrong import, missing fixture) → fix the test itself and re-run. Do NOT proceed to GREEN until the failure matches the intended behavior.
4. GREEN   -> Write the SIMPLEST code that makes the test pass
5. VERIFY  -> Run tests, confirm ALL pass (new + existing)
6. REFACTOR -> Clean up while keeping all tests green
7. REPEAT  -> Next behavior = next failing test

CRITICAL: Never skip VERIFY steps. A test that passes on first run proves nothing.

RED-GREEN-REFACTOR Cycle

See references/red-green-refactor.md for the detailed cycle with rules and verification steps.

Reference Guide

Quick Reference: Test Commands

Forbidden Behaviors

• Never write production code before a failing test
• Never skip the VERIFY RED step
• Never accept a test that passes on first run without investigation
• Never mock what you can test directly
• Never write more than one test at a time in RED phase
• Never add features beyond what the current test requires