SKILL.md
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
- 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.
When to Use
This skill is applicable to execute the workflow or actions described in the overview.
Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.