TDD GREEN Phase

Version: {{VERSION}}

When to Use

•RED phase test has been verified as failing
•Proceeding autonomously from RED phase
•Implementing feature to pass test

GREEN Phase Objective

Write the minimum code to make the test pass.

Workflow

Step 1: Understand Test Requirements

•What behavior is expected?
•What inputs does test provide?
•What output/result does test expect?

Step 2: Plan Minimal Implementation

Include:

•Minimum logic needed
•Required data structures
•Expected return values

Avoid:

•Features not in test
•Abstractions not yet needed
•Premature optimization

Step 3: Implement to Pass Test

Provide single code block:

code

TASK: [Brief description]

STEP 1: [Open implementation file]
STEP 2: [Navigate to location]
STEP 3: [Add implementation code]
STEP 4: [Explanation]
STEP 5: [Save file]
STEP 6: [Run test command]
STEP 7: [Verify test PASSES]
STEP 8: [Report back: Did test pass?]

Step 4: Verify and Proceed

If test passes: Proceed to REFACTOR phase If test fails: Revise implementation, repeat If other tests fail: Fix regressions first

Best Practices

YAGNI (You Aren't Gonna Need It)

Good: Implements exactly what test requires Poor: Implements untested features "just in case"

Simplest Thing That Works

code

Test: Function should return sum of two numbers

WRONG: Generic calculation engine with plugins
RIGHT: Function returns a + b

Hard-Code First, Generalize Later

code

Test expects result: 5
Implementation: return 5

Next test expects different result
-> Now implement real logic

Common Mistakes

•Over-Implementation - Adding features not required
•Premature Abstraction - Creating abstractions before needed
•Ignoring Test Failure Details - Not reading expectations
•Breaking Existing Tests - Run full suite

Implementation Strategies

Strategy	When	Example
Fake It	Simple test	`return 5`
Obvious	Clear solution	`return a + b`
Triangulation	Unsure how to generalize	Multiple tests force generalization

Checklist Before REFACTOR Phase

Resources

•resources/green-phase-checklist.md
•resources/minimal-implementation-guide.md
•resources/triangulation-examples.md

End of TDD GREEN Phase Skill