Stub a dependency function in sinon

I am using intern as testing framework and sinon for mocking the data. I dont want to hit the server for http requests during unit tests. So I have created a module that returns the data in deferred.promise as shown below:

define(["require", ..], function(require, ...) {
  function fakerequest(){
    dfd = new Deferred();
    setTimeout(function(){
      deferred.resolve(data);
    },100);
    return dfd.promise;
  }
  return fakerequest;
});

And this is the original AMD request module that hits an external server with http request:

define(["require", ..], function(require, ...) {
  function request(){
    dfd = new Deferred();
    ... 
    return dfd;
  }
  return request;
});

And this the module that I wanted to test. And it uses the request function for some data:

define(["require", ..], function(require, ...) {
  var QuerySomething = {
    execute: function(){
      ...
      return request();
    };
  }
  return QuerySomething;
});

Now I want to test the QuerySomething module but I dont want it to use the original request function but instead use the fakeRequest function. So in my intern test, I used sinon to stub the original request with the fake one.

registerSuite({
  name: 'QuerySomething',

  setup: function(){
    stub = sinon.stub(request, "request", fakeRequest);
  },

  teardown: function () {
    stub.restore();
  },

execute: function(){
  queryTask.execute(query).then(function(results){
    console.log(results);
  });
}

But I am getting this error:

TypeError: Attempted to wrap undefined property request as function

Can someone please let me know how to mock the dependency function?