In my case I have a `http_proxy` env variable on my development computer which passes all traffic to my vpn, however this proxy would fail to work when hostname is `localhost`, therefore when I'm testing my application it always fails because I setup my server at localhost, I want a method to force axios receiving a `none` for proxy config, currently if `proxy` property is `null` or `undefined` it will use the `http_proxy` env
test/unit/adapters/http.js
}
          },
          headers: {
            'Proxy-Authorization': 'Basic abc123'
          }
        }).then(function(res) {
          var base64 = new Buffer('user:pass', 'utf8').toString('base64');
          test.equal(res.data, 'Basic ' + base64, 'should authenticate to the proxy');
          test.done();
        });
      });
    });
  },
  testCancel: function(test) {
    var source = axios.CancelToken.source();
    server = http.createServer(function (req, res) {
      // 
      source.cancel('Operation has been canceled.');
    }).listen(4444, function() {
      axios.get('http://localhost:4444/', {
        cancelToken: source.token
      }).catch(function (thrown) {
        test.ok(thrown instanceof axios.Cancel, 'Promise must be rejected with a Cancel obejct');
        test.equal(thrown.message, 'Operation has been canceled.');
        test.done();
      });
    });
  }
};