
The fun, simple, flexible JavaScript test framework
Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser. It makes asynchronous testing simple and fun, with tests running serially for flexible and accurate reporting while mapping uncaught exceptions to the correct test cases.
Built-in support for testing async code using callbacks, promises, and async/await patterns
Use any assertion library you want - Chai, should.js, expect.js, or Node's built-in assert module
Supports BDD, TDD, Exports, QUnit, and Require-style interfaces for different testing methodologies
Run tests in both Node.js and the browser with the same framework
Tests run serially for accurate reporting and proper exception mapping to test cases
Optional --parallel flag to run tests concurrently for improved performance on large suites
before, after, beforeEach, and afterEach hooks for setup and teardown control
Unit and integration testing for Express, Koa, or other Node.js server applications
Testing REST and GraphQL API endpoints with flexible assertion libraries and async support
Writing tests first with TDD interface support and clean describe/it syntax for iterative development
Running the same test suite in both Node.js and browser environments for universal JavaScript code
Choose from built-in reporters like spec, dot, nyan, or create custom reporters for test output
Full support for ECMAScript Modules (ESM) for modern JavaScript projects
Run exclusive tests with .only(), skip tests with .skip(), or define pending tests without callbacks
Building tailored testing setups where you need fine-grained control over assertion libraries, reporters, and test structure

Open-source, AI-first business automation