ava

AVA is a minimalist test runner for Node.js that runs tests concurrently, achieving fast test execution by leveraging the asynchronous nature of JavaScript. AVA runs each test file in its own worker thread, and tests within a file run concurrently by default, encouraging developers to write tests that are truly isolated and do not depend on shared state. The framework has a simple, concise API with built-in assertion methods powered by the power-assert library, which provides detailed failure messages showing the values of all sub-expressions in failed assertions. AVA supports TypeScript natively, async/await, Observable testing, and snapshot testing. The test function receives a test object (t) with assertion methods: t.is(), t.deepEqual(), t.throws(), t.truthy(), and others. AVA uses ES modules by default and does not create global variables, requiring explicit imports. The framework provides .before(), .after(), .beforeEach(), and .afterEach() hooks, test macros for reusable test logic, and a watch mode that re-runs only affected tests. AVA is maintained by Sindre Sorhus and is designed for developers who prefer minimalism and fast execution.