patch for No-diff in colored and raw json output

[kounoike]

json-diff 0.3.1 has problem for same inputs.

$ cat a.json
[]
$ cat b.json
[]
$ node_modules/.bin/json-diff a.json b.json
 undefined
$ node_modules/.bin/json-diff -j a.json b.json

net.js:612
    throw new TypeError('invalid data');
          ^
TypeError: invalid data
    at WriteStream.Socket.write (net.js:612:11)
    at _Class.continuation (/home/chinachu/chinachu-scripts/node_modules/json-diff/lib/cli.js:101:31)
    at _Class.iced.Deferrals._Class._fulfill (/home/chinachu/chinachu-scripts/node_modules/json-diff/lib/cli.js:16:40)
    at /home/chinachu/chinachu-scripts/node_modules/json-diff/lib/cli.js:30:24
    at fs.js:268:14
    at Object.oncomplete (fs.js:107:15)

I wrote simple patch. But I can't test my patch.
How to test my npm-module?