Test-Driven Development (TDD)

Overview

Write the test first. Watch it fail. Write minimal code to pass.

Core principle: If you didn't watch the test fail, you don't know if it tests the right thing.

Violating the letter of the rules is violating the spirit of the rules.

Reference Files

Read only the references needed for the current test cycle:

• references/testing-patterns.md for naming, AAA structure, near-miss negatives, behavioral focus, and anti-pattern checks
• references/test-data-and-mocks.md for factories, mock boundaries, common boundary mocks, and env/time handling
• references/integration-and-live-proof.md when unit tests are not enough, or the plan requires real APIs, seeded data, browser flows, or stress proof

When to Use