How to simulate no connection in a mocha test

Question

I am just wondering if there is a way to simulate a "no connection" event in a mocha unit test. I have a method that return a promise that should wait for an internet connection with a polling strategy and I want to test it out with mocha. There is a method to achieve such a result.

Some code:

it('should wait for connection', function(done)
{
   this.timeout(2500);

   //simulate an internet connection drop here

   wait.connection().then(done);
   setTimeout(//activate connection, 2000);
});

Thank you for any response.

[EDIT]: Here there is the code I want to test:

var wait = {
connection: function()
  {
    'use strict';
    var settings = {retry: 1000};

    return new Promise(function(resolve)
    {
      (function poll()
      {
        needle.get('https://api.ipify.org', function(error, response)
        {
          if(!error && response.statusCode === 200 && /^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$|^(([a-zA-Z]|[a-zA-Z][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z]|[A-Za-z][A-Za-z0-9\-]*[A-Za-z0-9])$|^\s*((([0-9A-Fa-f]{1,4}:){7}([0-9A-Fa-f]{1,4}|:))|(([0-9A-Fa-f]{1,4}:){6}(:[0-9A-Fa-f]{1,4}|((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){5}(((:[0-9A-Fa-f]{1,4}){1,2})|:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){4}(((:[0-9A-Fa-f]{1,4}){1,3})|((:[0-9A-Fa-f]{1,4})?:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){3}(((:[0-9A-Fa-f]{1,4}){1,4})|((:[0-9A-Fa-f]{1,4}){0,2}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){2}(((:[0-9A-Fa-f]{1,4}){1,5})|((:[0-9A-Fa-f]{1,4}){0,3}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){1}(((:[0-9A-Fa-f]{1,4}){1,6})|((:[0-9A-Fa-f]{1,4}){0,4}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(:(((:[0-9A-Fa-f]{1,4}){1,7})|((:[0-9A-Fa-f]{1,4}){0,5}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:)))(%.+)?\s*$/.test(response.body))
            resolve();
          else
            wait.for(settings.retry).then(poll);
        });
      })();
    });
  }
};

In this case the Promise will remain pending since a new connection is available. How can I simulate an error on the needle get request?

Answer 1

You can use sinon to stub needle.get

var needle = require("needle");
var sinon = require("sinon");;

before(() => {
    sinon.stub(needle, "get", (url, calback) => {
        var dummyError = {};
        callback(dummyError);
    })
});

// Run your 'it' here 

after(() => {
    needle.get.restore();
});

Answer 2

You can use nock.disableNetConnect(): https://github.com/nock/nock#enabledisable-real-http-requests