Assert inner function called

Question

Assert inner function called

I have a file foo.js that looks like this:

var exec = require('child_process').exec
...
function start(){
  ...
  exec('open -g http://localhost:<port>');  // opens a browser window
}
// EOF

I want to test that when I call the start() function, a browser window gets opened. Ideally, I'd like to use Sinon to stub out exec (so that we don't actually open a browser window during automated tests), and assert that exec was called. I've tried many ways, none of which work. For example in foo_test.js:

var subject = require('../lib/foo');

describe('foo', function(){
  describe('start', function(){
    it('opens a browser page to the listening address', function(){
      var stub = sinon.stub(subject, 'exec', function(){
        console.log('stubbed exec called');
      });  // fails with "TypeError: Attempted to wrap undefined property exec as function"
    });
  });
});

How would I go about doing this?

node.js
sinon

Answer 1

Not sure if this is what you're looking for, but a quick search returned:

https://github.com/arunoda/horaa

Basically, it allows you to stub out libraries. From the examples:

Your Code

//stored in abc.js
exports.welcome = function() {
    var os = require('os');

    if(os.type() == 'linux') {
        return 'this is a linux box';
    } else {
        return 'meka nam linux nemei :)';
    }
};

Test Code (note the mocking of OS)

//stored in test.js
var horaa = require('horaa');
var lib = require('./abc'); // your code
var assert = require('assert');

//do the hijacking
var osHoraa = horaa('os');
osHoraa.hijack('type', function() {
    return 'linux';
});

assert.equal(lib.welcome(), 'this is a linux box');

//restore the method
osHoraa.restore('type');

Hope that helps.