name: tdd description: Test-Driven Development workflow for the Builder agent. Ensures code is written test-first with proper red-green-refactor cycles. applies_to:

• builder

Test-Driven Development

Follow this cycle for every piece of new functionality:

The Red-Green-Refactor Cycle

1. Red — Write a Failing Test First

Before writing any implementation:

• Write a test that describes the expected behavior
• Run it to confirm it fails (for the right reason)
• The failure message should clearly state what's missing

2. Green — Write Minimal Code to Pass

• Write the simplest implementation that makes the test pass
• Do not add features the test doesn't require
• Do not optimize prematurely
• Run the test to confirm it passes

3. Refactor — Clean Up

• Remove duplication
• Improve naming
• Extract functions if needed
• Run tests again to confirm nothing broke

Rules

1. Never write implementation before the test — the test defines the contract
2. One behavior per test — test names should read like specifications
3. Test error paths too — invalid input, missing data, network failures
4. Tests must be independent — no shared mutable state between tests
5. Tests must be fast — mock external services, use in-memory databases

Test Structure

// Arrange — set up preconditions
// Act — call the function under test
// Assert — verify the result

When to Skip TDD

• Exploratory/prototype code (but add tests before merging)
• Trivial getters/setters
• UI layout code (use visual testing instead)