There are some good testing libraries for node (eg. https://github.com/visionmedia/mocha, by the same author as Express), that make async testing fairly painless. However, there are things like DB setup/teardown that aren't integrated and you might be used to getting "for free" with other frameworks (eg. Django). I'm curious to hear what the parent commenter has found to be a roadblock.

Here is a little bit of background. I'm writing RESTful service using node and I really like how easy is to write async code. There are tools in node that allows me testing it - one example here https://github.com/flatiron/api-easy but there are more that I have considered. The problem I have with all those options: I need to write too much code to produce simple test. Python unittest and python-requests modules allow me writing much simpler code that actually does the same. There is simply no sense writing async code for unit-test like testing. Node is good for writing async code and I'm really happy this that.

Client side async code has its own place as well. I really enjoyed writing complex load tests with node. That was simpler than investigating python options and node is faster in such scenario.