agent: agent

description: Test-driven development cycle — write the test first, then implement

TDD Workflow

Follow the RED → GREEN → IMPROVE cycle strictly. Do not write implementation code before a failing test exists.

Cycle

1. RED — Write the failing test

• Write a test that describes the desired behavior.
• Run it. It must fail before continuing.
• Use Arrange-Act-Assert structure.
• Name tests descriptively: returns empty array when no items match filter, not test itemFilter.

2. GREEN — Minimal implementation

• Write the minimum code needed to make the test pass.
• Do not over-engineer at this stage.
• Run the test again — it must pass.

3. IMPROVE — Refactor

• Clean up duplication, naming, structure.
• Keep all tests passing after each change.
• Check coverage: target ≥ 80%.

Test Layer Checklist

• [ ] Unit — pure functions, utilities, isolated components
• [ ] Integration — API endpoints, database operations, service boundaries
• [ ] E2E — at least one critical user flow covered

Quality Gates

Before marking the feature done:

• [ ] All tests pass
• [ ] Coverage ≥ 80%
• [ ] No skipped/commented-out tests
• [ ] Edge cases covered: empty input, nulls, boundary values, error paths

Anti-patterns to Avoid

• Writing implementation before tests
• Testing implementation details instead of behavior
• Mocking too deeply (prefer integration tests over excessive mocks)
• Assertions that always pass (expect(true).toBe(true))