javascript-unit-testing

SKILL.md

Expert guidance for writing maintainable, trustworthy unit tests in JavaScript and TypeScript using Jest. Based on "The Art of Unit Testing, Third Edition" by Roy Osherove with Vladimir Khorikov (Manning, 2024).

A unit of work is all actions between an entry point (function/method we trigger) and one or more exit points (observable results).

Use factory methods instead of beforeEach() to avoid scroll fatigue and keep tests self-contained.

Writing high-quality unit tests for JavaScript and TypeScript using Jest. Covers test structure (AAA pattern, USE naming), breaking dependencies (stubs, mocks, dependency injection), testing async code (promises, callbacks, timers), avoiding flaky tests, and test-driven development. Use when writing tests, debugging test failures, refactoring tests for maintainability, or questions about Jest, TDD, mocks, stubs, or test best practices. Source: el-feo/ai-context.

View raw