uvu

uvu is a lightweight JavaScript testing framework designed for speed and simplicity. It targets Node.js and browser environments, offering a minimal API and a small runtime footprint. The project emphasizes fast test execution with low overhead, making it suitable for small projects, libraries, and microservices, as well as as a lightweight alternative to larger testing ecosystems.

API and usage: Tests are defined by importing the test function from the uvu package and the assertion helpers from the uvu/assert module. A test is declared by giving a name and a function that contains assertions. Tests can be asynchronous by returning a promise or using async functions. After defining tests, the test runner is started by invoking test.run(). The framework reports results to the console and exits with a nonzero status on failure.

Design and philosophy: uvu aims to be minimal and fast, avoiding heavy configuration or global state. It emphasizes explicit test declarations rather than automatic discovery, and it strives for deterministic behavior with quick startup times. It supports modern JavaScript features and ECMAScript module environments; in TypeScript projects, tests can be written with appropriate transpilation.

Ecosystem and usage context: uv u is commonly used as a compact alternative to larger frameworks such as Jest or Mocha when speed and simplicity are priorities. The project is open source and hosted on a public repository, where the core runtime and the separate uvu/assert module are maintained. The assertion helpers in uvu/assert provide a focused set of checks for validating test outcomes. The framework has an active community with examples and guidance for common testing scenarios.