Mocha vs Testem

Mocha is a free, open-source JavaScript test framework that runs in Node.js and browsers. Tests run serially by default, and uncaught exceptions are associated with their test cases. Asynchronous tests can use callbacks or returned promises, while parallel execution is available in Node.js but not in browsers. The command-line interface defaults to the BDD interface and spec reporter; browser runs default to the HTML reporter, and reporters can be configured. Installation as a development dependency is documented for npm, pnpm, and yarn. Mocha 12 requires Node.js ^20.19.0 or >=22.12.0, and browser builds document support for evergreen Chrome, Edge, Firefox, and Safari. It supports JavaScript and TypeScript, parameterized cases, and lists editor-related packages for TextMate, JetBrains IDEs, Wallaby.js, Emacs, and VS Code. Built-in mocks are not included. The project points users to Discord and documentation explainers for more information.

Testem is a JavaScript test runner for running tests in Node.js, real desktop browsers, or a launcher you configure. It supports Jasmine, QUnit, Mocha, and custom framework adapters, and can be used for unit, integration, end-to-end-style, or custom test setups. Browser runs can use Chrome, Firefox, Safari, or Edge, including a Headless Chrome launcher. In development mode, a terminal interface watches project files and reruns tests after relevant changes; CI mode can run tests in available browsers in parallel. Testem includes CI reporters for TAP, dot, xunit, and TeamCity, with custom reporters available. Listed preprocessing support includes Babel, TypeScript, Browserify, ESLint, JSHint, JSLint, and CoffeeScript. Its API provides startDev, startCI, and startServer modes, and coverage reporting is supported. It works with GitHub Actions, Jenkins, and TeamCity. Testem is free and open source under the MIT license, and runs on Linux, macOS, and Windows. It requires a supported Node.js runtime: ^22.17.0, ^24.0.0, or >=26.0.0.