aaa-pattern_skill

Overview

This skill enforces the Arrange-Act-Assert (AAA) pattern for tests. It helps you detect and fix mixed phases so tests remain readable, maintainable, and debuggable. Use it when test structure or intent is unclear.

How this skill works

The skill inspects test code for interleaved setup, actions, and assertions. It flags smells like expect() calls between actions, multiple acts in one test, or assertions scattered throughout. It then recommends restructuring tests into explicit Arrange, Act, and Assert sections, and suggests splitting tests when multiple behaviors are mixed.

When to use it

• Writing any unit or integration test
• Test logic is hard to follow or name
• You see assertions between actions
• Multiple actions or behaviors are combined in one test
• Enforcing consistent test style across a codebase

Best practices

• Always separate Arrange, Act, and Assert in that order
• Keep Act to a single behavior; move repeated setup into Arrange
• Use comments or section breaks to make phases explicit
• Allow multiple asserts only when they verify one logical behavior
• If you need multiple acts, create separate tests

Example use cases

• Refactor a failing test where assertions are sprinkled between operations
• Review new tests in a pull request for mixed phase smells
• Write clear BDD-style tests using Given-When-Then mapped to AAA
• Enforce consistent test layout in a shared TypeScript test suite
• Educate teammates by converting messy tests into explicit AAA examples