Mocha runs independently from the [assertion library](http://visionmedia.github.io/mocha/#assertions), so you can choose which assertion format works best for you. Mocha most often is run in combination with assertion library [Chai](http://chaijs.com).
Ranked in these QuestionsQuestion Ranking
Pro Allows screenshots (either the full page or parts of it) if performing UI testing
There are times where you don't want to open up a browser for screencaps, that is where CasperJS comes to use, it can render the page using its own rendering engine and take and save a screenshot for you, all via the commandline
Pro Easy to understand
Since all webdevs know JS, the start-up time of learning the framework will be reduced to zero, as your team can be productive from day one.
Pro Easily integrates with other applications
Due to the simplicity of the framework, not only other libraries can be built with it, but it can be integrated with any web application as well.
Pro Write tests with Behavior Driven Development (BDD)
Allows developers to choose their development process. Not only TDD but also BDD.
Pro Makes Asynchronous testing extremely easy
No need to write tricky statements for Async testing. Mocha gives you a
done callback. Place this
done parameter in your callback function, that'll let Mocha know that you've written an asynchronous function.
Pro Integrates really well with NodeJS
The Mocha test framework itself runs on NodeJS, hence it makes everything related to it extremely simple. With Mocha's simple syntax and speed, testing your node.js app just got a whole lot easier.
Pro Runs in Node.js and the browser
Mocha has a browser build as well as a node command line program so you can test in client and server side environments.
Pro Custom full color test reporters
Mocha has multiple test reporters built in and you can create your own as well. The test reporters have full color and makes it easy to see if your tests fail or not.
Pro Easy to add support for Generators
Aside from the numerous benefits with generators in your application, You can now also integrate generators into your test suite. By using mocha, all you have to do is enable support for generators.
Con Not for unit testing but rather UI testing
These are two extremely different concepts. CasperJS should be removed from this list
Con Cannot guarantee 100% accurate Webkit-based browser screenshots
QtWebKit is the rendering engine used by CasperJS. Keep in mind this is NOT the same rendering engine as Chrome; hence, if you want to be 100% sure of the results, you must run a Webkit browser (such as Chrome) yourself.
Con No atomic tests
Tests cannot be ran in random order.
Con Can be intimidating for beginners
While some testing frameworks are complete out of the box, Mocha requires developers to select and set up assertion libraries and mocking utilities. For someone who is just starting to learn how to build tests this can be scary as they will also have to choose which libraries to use and learn them too.