what's the least resistance path to debugging mocha tests?

Edit Nov 2016: Node now has a built in debugger that you can start with --inspect. This answer explains it: https://stackoverflow.com/a/39901169/30946.

I'm building a mocha test in coffeescript. Right at the top of the test I have:

require "../assets/js/theObject.coffee"
debugger
ss = new TheObject()

I'd like to stop on that debugger line because the object in theObject.coffee isn't being loaded. I'm using node-inspector and it works, sorta.

The process that I have is:

1. start node-inspector
2. run the test at the command line with mocha --compilers coffee:coffee-script ./test/theObjectTests.coffee --ui bdd -d --debug-brk
3. go to the node-inspector page, refresh it if it is already open
4. wait for the file theObject.coffee to be loaded, then put a breakpoint on the correct line

There must be an easier way. It seems like I should be able to have a debugger running and just have it stop on that debugger line, but I'm not able to find that.

I have WebStorm, which has a debugger (this article discusses setting it up to run mocha tests, but it didn't help me), but when I start it, it fails. The command that's running in the WebStorm debug window is:

"C:\Program Files\nodejs\node.exe" --debug-brk=64232 C:\Users\jcollum\AppData\Roaming\npm\_mocha

C:\Users\jcollum\AppData\Roaming\npm\_mocha:2
basedir=`dirname "$0"`

I suspect that might be a windows specific issue.

Env: Windows 7, Webstorm, node 0.8.16, mocha 1.7.4, git-bash

The question: if you're starting from scratch with Mocha, what's the easiest way to get a debugger going that will stop on a debugger line easily? Easy is the keyword here.

Edit: since asking this I've stopped using Windows and am working in Ubuntu. My mocha debugging process (which I use infrequently) is the same.

Solution 1:

Edit, years later: the shortest path in Node 6+ is: mocha --debug-brk --inspect ./test.js coupled with the Node Inspector Manager plugin.

Many weeks later, no answers. Here's the quickest path that I found.

1. write mocha tests
2. install node-inspector
3. start node-inspector -- it will now be listening on 5858
4. start the mocha test with --debug-brk
5. at this point the mocha test is paused on the first line
6. open a web browser and go to localhost:5858
7. (optional: add a debugger line at the top of your test file, set breakpoints after it stops in that file)
8. hit F10 to get the code to go
9. node-inspector will stop on any line that has debugger on it. Occasionally it won't move the code file's window to the right place, so you'll have to hit F10 to get it to step to the next line and show where it's at in the file.

Command line:

node-inspector & mocha --compilers coffee:coffee-script/register ./test/appTests.coffee --ui bdd -d -g "should X then Y" --debug-brk

Solution 2:

In addition to @jcollum's answer above, I have found instead of using the --debug-brk flag, it is better to just use the --debug flag with -w (watch)

That way, when you add and remove debugger lines from your code, mocha will reload the tests automatically and your node-inspector will pause on the appropriate line.

This saves having to revisit the terminal constantly restarting the tests, then needlessly hitting "continue" in the debugger to get past the first line of the source.

Solution 3:

With the latest versions of Mocha and node-inspector, this has been working great for me:

$ node-debug ./node_modules/mocha/bin/_mocha

It loads up the local Mocha executable as the debugged process, stopping on the first line for you to set up your breakpoints.