What problem does it solve? Test suites often become brittle, slow, flaky, or unreadable over time, turning a safety net into a maintenance burden. This Skill provides the canonical catalogue of test-automation patterns and smells from Gerard Meszaros's "xUnit Test Patterns" so tests stay maintainable, trustworthy, and clearly communicative. ## Core Features & Use Cases - Test Double Taxonomy: Choose and name the right double — Dummy, Stub, Spy, Mock, or Fake — based on the role it plays in the test, including the stub-vs-mock distinction. - Fixture & Verification Patterns: Structure the four-phase test, design fresh vs shared fixtures, and apply Object Mother, Test Data Builder, Custom Assertions, and Expected Object comparisons. - Smell Diagnosis: Identify and fix code smells (Mystery Guest, Eager Test, Conditional Test Logic), behaviour smells (Erratic Test, Fragile Test, Assertion Roulette, Slow Tests), and project-level smells. - Use Case: When a test suite starts failing intermittently in CI, use this Skill to trace the flakiness to a shared mutable fixture or uncontrolled clock, then refactor to Fresh Fixtures and isolated test data. ## Quick Start Ask Claude to review your test file for xUnit test smells and suggest the right test doubles and fixture strategy for each test.
