TDD Cycle Skill

Goal

Implement any feature using strict Test-Driven Development: write the failing test first, implement minimal code to pass it, then refactor. The false-positive check is mandatory.

Steps

Phase 1 — Red (Failing Test)

1. Understand the requirement

   • Read the relevant task from project/TASKS.md or the user's description
   • Identify the expected behavior as a verifiable predicate
   • Write the requirement in EARS format if not already: "WHEN [X] THE SYSTEM SHALL [Y]"

2. Write the failing test

   • Create the test file if it doesn't exist (mirrors source file path in tests/ directory)
   • Write the minimal test that captures the expected behavior
   • Use descriptive test names: "should return 422 when email is invalid"
   • Test ONE behavior per test case (single assertion focus)