use node-inspector to debug mocha test in es6

I have a react app written in es6, and I’m using mocha to unit test it. For some reason, the unit test failed and I wanted to debug it to find out why.

• I first tried node-debug command

node-debug mocha test/.setup.js test/**/*-test.js           

and node-inspector successfully stopped on _mocha, but after I insert breakpoints on my .setup.js, it never hit my break point and went straight to finish. So basically, it doesn’t work at all!

• I then tried run node-inspector in advanced mode, i.e. run node-inspector in a seperate shell, then start mocha in debug mode

shell 1:   node-inspector
shell 2:   mocha --debug-brk  test/.setup.js test/**/*-test.js           

and I have got it work! unbelievable! the only issue is performance, it took node-inspector a very long time (~5 minutes) to load the transpiled es5 scripts, and I once thought node-inspector has died (when attaching to node from vs code, it didn’t take that long! so it’s not a babel issue).

Question: why node-debug doesn’t work in my scenario , and why running in separate shell works, but take such a long time?

---

running environment

$ npm list -g node-inspector mocha-cli                                                                                                               
C:\Users\admin\AppData\Roaming\npm                                                                                                                   
├── mocha-cli@1.0.1                                                                                                                                  
└── node-inspector@0.12.8          

$ npm list mocha                                                                                                                                     
enzyme-example-mocha@0.1.0 d:\__work\enzyme-example-mocha                                                                                            
└── mocha@2.5.3                                               

$ node -v                                                                                                                                            
v4.4.6           

[tshinnic]

I ended up using this:

node  --inspect-brk  node_modules\mocha\bin\_mocha  --no-timeouts  test\TableGdef01.js

to finally allow setting breakpoints in my code under Mocha testing. Switching to inspect debugging because:

(node:6208) DeprecationWarning: node --debug is deprecated. Please use node --inspect instead. 

This under Windows 10, node 7.7.4, mocha 3.3.0

[MagicDuck]

@bochen2014 I ran into the same issue, I think it’s because bin/mocha spawns a sub-process which executes bin/_mocha

I found that out from this comment at the top of the bin/mocha file:

/**
 * This tiny wrapper file checks for known node flags and appends them
 * when found, before invoking the "real" _mocha(1) executable.
 */

I was successful running it like so:

node-debug _mocha test --recursive --watch