# Tdd Workflow

> Test-Driven Development workflow principles. RED-GREEN-REFACTOR cycle.

- Skill: `lev-os/tdd-workflow` (Agent Skill)
- Install (CLI): `npx skillmds@latest add lev-os/tdd-workflow`
- Raw SKILL.md: https://api.skillmd.com/api/skills/lev-os/tdd-workflow/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: lev-os (https://skillmd.com/u/lev-os)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/lev-os/tdd-workflow

---


# TDD Workflow

> Write tests first, code second.

---

## 1. The TDD Cycle

```
🔴 RED → Write failing test
    ↓
🟢 GREEN → Write minimal code to pass
    ↓
🔵 REFACTOR → Improve code quality
    ↓
   Repeat...
```

---

## 2. The Three Laws of TDD

1. Write production code only to make a failing test pass
2. Write only enough test to demonstrate failure
3. Write only enough code to make the test pass

---

## 3. RED Phase Principles

### What to Write

| Focus | Example |
|-------|---------|
| Behavior | "should add two numbers" |
| Edge cases | "should handle empty input" |
| Error states | "should throw for invalid data" |

### RED Phase Rules

- Test must fail first
- Test name describes expected behavior
- One assertion per test (ideally)

---

## 4. GREEN Phase Principles

### Minimum Code

| Principle | Meaning |
|-----------|---------|
| **YAGNI** | You Aren't Gonna Need It |
| **Simplest thing** | Write the minimum to pass |
| **No optimization** | Just make it work |

### GREEN Phase Rules

- Don't write unneeded code
- Don't optimize yet
- Pass the test, nothing more

---

## 5. REFACTOR Phase Principles

### What to Improve

| Area | Action |
|------|--------|
| Duplication | Extract common code |
| Naming | Make intent clear |
| Structure | Improve organization |
| Complexity | Simplify logic |

### REFACTOR Rules

- All tests must stay green
- Small incremental changes
- Commit after each refactor

---

## 6. AAA Pattern

Every test follows:

| Step | Purpose |
|------|---------|
| **Arrange** | Set up test data |
| **Act** | Execute code under test |
| **Assert** | Verify expected outcome |

---

## 7. When to Use TDD

| Scenario | TDD Value |
|----------|-----------|
| New feature | High |
| Bug fix | High (write test first) |
| Complex logic | High |
| Exploratory | Low (spike, then TDD) |
| UI layout | Low |

---

## 8. Test Prioritization

| Priority | Test Type |
|----------|-----------|
| 1 | Happy path |
| 2 | Error cases |
| 3 | Edge cases |
| 4 | Performance |

---

## 9. Anti-Patterns

| ❌ Don't | ✅ Do |
|----------|-------|
| Skip the RED phase | Watch test fail first |
| Write tests after | Write tests before |
| Over-engineer initial | Keep it simple |
| Multiple asserts | One behavior per test |
| Test implementation | Test behavior |

---

## 10. AI-Augmented TDD

### Multi-Agent Pattern

| Agent | Role |
|-------|------|
| Agent A | Write failing tests (RED) |
| Agent B | Implement to pass (GREEN) |
| Agent C | Optimize (REFACTOR) |

---

> **Remember:** The test is the specification. If you can't write a test, you don't understand the requirement.

## Technique Map
- **Role definition** - Clarifies operating scope and prevents ambiguous execution.
- **Context enrichment** - Captures required inputs before actions.
- **Output structuring** - Standardizes deliverables for consistent reuse.
- **Step-by-step workflow** - Reduces errors by making execution order explicit.
- **Edge-case handling** - Documents safe fallbacks when assumptions fail.

## Technique Notes
These techniques improve reliability by making intent, inputs, outputs, and fallback paths explicit. Keep this section concise and additive so existing domain guidance remains primary.

## Prompt Architect Overlay
### Role Definition
You are the prompt-architect-enhanced specialist for tdd-workflow, responsible for deterministic execution of this skill's guidance while preserving existing workflow and constraints.

### Input Contract
- Required: clear user intent and relevant context for this skill.
- Preferred: repository/project constraints, existing artifacts, and success criteria.
- If context is missing, ask focused questions before proceeding.

### Output Contract
- Provide structured, actionable outputs aligned to this skill's existing format.
- Include assumptions and next steps when appropriate.
- Preserve compatibility with existing sections and related skills.

### Edge Cases & Fallbacks
- If prerequisites are missing, provide a minimal safe path and request missing inputs.
- If scope is ambiguous, narrow to the highest-confidence sub-task.
- If a requested action conflicts with existing constraints, explain and offer compliant alternatives.