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tdd-green-phase

Testing & Quality
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Guide experienced developers through GREEN phase of TDD cycle - writing minimal implementation to pass failing tests

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Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/development/tdd-green-phase-rubrical-studios-gh-pmu/SKILL.md

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TDD GREEN Phase

Version: 0.19.0 Source: Skills/tdd-green-phase/SKILL.md

Guide through GREEN phase: implementing minimum code to make failing test pass.

When to Use

  • RED phase test verified as failing
  • Proceeding autonomously after RED phase
  • Moving from RED to GREEN in TDD cycle

Objective

Write the minimum code to make the test pass.

Correct: Implements exactly what test requires, simplest solution Incorrect: Over-engineers, adds untested features, premature optimization

Workflow

Step 1: Understand Test Requirements

  • What behavior is expected?
  • What inputs/outputs?
  • What edge cases covered?

Step 2: Plan Minimal Implementation Avoid: Features not in test, abstractions not needed, premature optimization

Step 3: Implement (Single Code Block)

TASK: [Description]
STEP 1: Open implementation file
STEP 2: Navigate to location
STEP 3: Add/modify implementation code
STEP 4: Context about choices
STEP 5: Save file
STEP 6: Run test command
STEP 7: Verify test PASSES
STEP 8: Report: Did test pass?

Step 4: Verify Success

  • Test executed without errors
  • Test passed (green)
  • No other tests broke
  • Implementation is minimal

Step 5: Analyze

  • Passes → Proceed autonomously to REFACTOR phase
  • Still fails → Revise implementation
  • Other tests fail → Fix regressions first

Principles

  1. YAGNI: Implement only what test requires
  2. Simplest Thing: Hard-coded values acceptable if test passes
  3. Let Tests Drive Design: Test tells you the interface
  4. Hard-Code First: Generalize when more tests require it

Implementation Strategies

  • Fake It: Return expected value (temporary)
  • Obvious Implementation: Straightforward solution
  • Triangulation: Multiple tests force generalization

Anti-Patterns

  • Feature creep (adding untested features)
  • Optimization before profiling
  • Copy-paste without understanding

Checklist

  • Target test now PASSES
  • Implementation is minimal
  • No regressions (full suite green)
  • Ready to proceed to REFACTOR phase

End of TDD GREEN Phase Skill