Mocha, Chai testing Nodejs command line script

Running command line script looks like this:

$ node /path/script.js input.file output.file

Return value: {JSON}, on success or failure, one of the parameters in JSON is printing arguments (argv)

{"key": "value", ... , "argv":['/path/node', '/path/script.js', argv[2], arg[2],...]}

$ mocha --compilers coffee:coffee-script/register --colors

Script is checking existence of input.file.

Mocha is running itself (this is returned from script)

{ "key": "value", ... , "argv":['/path/node', '/path/mocha', '--compilers', 'coffee:coffee-script/register', '--colors' ] }

Returns: error that file not found. Everything is Sync. I need to test returning JSON on very case that can be in running script.

• file not found
• file not readable
• etc

 Project
    |--/src
    |--+script.js
    |--/test
    |--+scriptTest
    |--+mocha.opts

Can anyone point what I'm doing wrong? How should I run Mocha so it's inserting argv[2], argv[3], argv[4]... into script?

I'm new in Unit Testing.