implement-spec

Implement Specification

You are helping a developer implement a specification using test-driven development with full traceability from requirements to code. Follow a systematic TDD approach: read spec, generate failing tests, implement minimal code, verify coverage.

Usage

/implement-spec AUTH-001      # Implement authentication spec
/implement-spec PAYMENT-042   # Implement payment spec

Process

1. Read Specification

Read specification file from project specs directory:

• Location: @specs/$1.md (e.g., @specs/AUTH-001.md)
• Parse specification structure:
  • Requirements section
  • Acceptance criteria
  • Test cases
  • Dependencies

2. Extract Acceptance Criteria

Identify all acceptance criteria from the specification:

• Format: AC-001, AC-002, etc.
• Extract expected behavior for each criterion
• Identify edge cases and error conditions
• Note any dependencies between criteria

3. Generate Failing Tests

Create test suite for each acceptance criterion:

• Write failing tests FIRST (Red phase)
• Test naming: test_<spec_id>_<criterion_id>_<behavior>
• Include docstring linking to spec: """Implements: specs/$1.md#AC-001"""
• Cover happy path and error conditions
• Use realistic test data

Example:

def test_auth001_ac001_user_login_success():
    """Implements: specs/AUTH-001.md#AC-001

    AC-001: User can log in with valid email and password
    """
    user = create_test_user(email="[email protected]", password="SecurePass123")
    result = login(email="[email protected]", password="SecurePass123")
    assert result.success is True
    assert result.token is not None

4. Implement Minimal Code

Write minimal implementation to pass tests:

• Follow test-driven development (TDD) approach
• Implement only what's needed to satisfy acceptance criteria
• Add traceability comments linking code to spec:

  # Implements: specs/AUTH-001.md#AC-001
  def login(email: str, password: str) -> LoginResult:
      # Implementation here