Debugging with NodeJS and Expresso
NodeJS
git clone https://github.com/joyent/node.git
Expresso
git clone https://github.com/visionmedia/expresso.git
After installing NodeJS and Expresso you will have to make a change to your Expresso file to allow for debugging.
Add the following statement to your code to set a breakpoint in the debugger:
debugger;
Next, run the following to start up the NodeJS debugger and use Expresso for your unit tests.
Using TextMate
mate $(which expresso)
Using vim
vim $(which expresso)
Change the first line to read:
#!/usr/bin/env node debug
Executing your tests with expresso now uses the node debugger.*
expresso test.js
For those looking for a browser based debugging environment, check out node-inspector.
Node Inspector
git clone https://github.com/dannycoates/node-inspector.git
To get this to work with Expresso, I had to change the hashbang to be:
#!/usr/bin/env node —debug-brk
node-inspector &
Now, running expresso test.js will open your file in a web browser for debugging. You will have to point your browser to node-inspector and you can explore your breakpoints and watch variables just like you were in WebKit.
Happy coding, twitternets!
* There are mixed feelings about this in the develosphere, as debugging unit tests is a bit like betting on black /and/ red. I am illustrating how to do it, not advocating its use. Personally I think its better to rely on the unit testing framework to surface errors but stepping through with debugger; statements is sometimes the only way to dive deep into the problem.
