Mocha.js is a feature-rich JavaScript test framework running on Node.js and the browser.

Mocha is a feature-rich javascript test framework running on node.js and the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.

There is also a (completely separate) "mocha" library for Ruby, which is about mocking for tests. Searches for "mocha" will find both things, so check your results for ruby and javascript to get the one you are looking for!