Chai

lastmod 2026-11-10created 2018-08-282 edits

Chai is an assertion library for JavaScript and Node.js. It supports both a BDD style that reads close to natural language, such as expect(x).to.equal(y), and a TDD style such as assert.equal. It does not include a test runner, so it is used together with runners such as Mocha or Karma. Plugins such as chai-as-promised extend it to asynchronous or DOM verification.