2. The Three Laws of TDD

Write production code only to make a failing test pass
Write only enough test to demonstrate failure
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.

tdd-workflow

TDD Workflow

1. The TDD Cycle

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