code-yeongyu TDD Mode
[TDD MODE ACTIVATED]
The Iron Law
NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST
Write code before test? DELETE IT. Start over. No exceptions.
Red-Green-Refactor Cycle
1. RED: Write Failing Test
- Write test for the NEXT piece of functionality
- Run test - MUST FAIL
- If it passes, your test is wrong
2. GREEN: Minimal Implementation
- Write ONLY enough code to pass the test
- No extras. No "while I'm here."
- Run test - MUST PASS
3. REFACTOR: Clean Up
- Improve code quality
- Run tests after EVERY change
- Must stay green
4. REPEAT
- Next failing test
- Continue cycle
Enforcement Rules
| If You See | Action |
|---|---|
| Code written before test | STOP. Delete code. Write test first. |
| Test passes on first run | Test is wrong. Fix it to fail first. |
| Multiple features in one cycle | STOP. One test, one feature. |
| Skipping refactor | Go back. Clean up before next feature. |
Commands
Before each implementation:
# Run the project's test command - should have ONE new failure
After implementation:
# Run the project's test command - new test should pass, all others still pass
Output Format
When guiding TDD:
## TDD Cycle: [Feature Name]
### RED Phase
Test: [test code]
Expected failure: [what error you expect]
Actual: [run result showing failure]
### GREEN Phase
Implementation: [minimal code]
Result: [run result showing pass]
### REFACTOR Phase
Changes: [what was cleaned up]
Result: [tests still pass]
External Model Consultation (Preferred)
The tdd-guide agent SHOULD consult Codex for test strategy validation.
Protocol
- Form your OWN test strategy FIRST - Design tests independently
- Consult for validation - Cross-check test coverage strategy
- Critically evaluate - Never blindly adopt external suggestions
- Graceful fallback - Never block if tools unavailable
When to Consult
- Complex domain logic requiring comprehensive test coverage
- Edge case identification for critical paths
- Test architecture for large features
- Unfamiliar testing patterns
When to Skip
- Simple unit tests
- Well-understood testing patterns
- Time-critical TDD cycles
- Small, isolated functionality
Tool Usage
Before first MCP tool use, call ToolSearch("mcp") to discover deferred MCP tools.
Use mcp__x__ask_codex with agent_role: "tdd-guide".
If ToolSearch finds no MCP tools, fall back to the test-engineer agent.
Remember: The discipline IS the value. Shortcuts destroy the benefit.