Unit testing framework for node.js that specifically supports testing async code?

Question

There are 30+ testing frameworks listed on the node.js module list...

Which frameworks are most popular? And what are their pros and cons?

I'm looking for a framework that supports unit testing of code that has a lot of async callbacks (probably like most other node projects). Also, I'm looking for something rather simple and small than complex.

So far I've looked into:

• Nodeunit is straightforward and supports async code by letting you define how many assertions you expect to be called and when a test is done.
• Vowsjs looks interesting. Allows you to nicely structure the tests and comes with many advanced features. Not sure whether these features are actually useful, through, or if they rather stand in your way?

Answer 1

expresso and vows are the most popular options. Although there are many good options out there. Update: As of Nov./2011, Mocha is the successor to expresso, according to the Readme.md at the expresso repository. should.js is often used with Mocha to allow BDD-style assertions.

Whatever you choose, I recommend using gently to stub core or third party modules.

I use/maintain testosterone, a little testing framework that runs test on serial so you can abuse gently. Not so many people using it though.

Answer 2

Since March 2012 we've been using Nodeunit and haven't looked back. It's straightforward and easy to work with, it lets you choose between module-level and class-level fixtures (setup/teardown), it's got a reasonable set of built-in assertions, and its command-line tool is very flexible. Try combining it with nodemon, too.

We looked a Vows briefly but didn't want a whole new weird syntax for defining tests. All you need are assertions, fixtures, and a decent harness, and Nodeunit fits the bill perfectly.