How to unit test MVC controller action that is using HttpClient

I am trying to test the following MVC controller Action, which is calling out to Web API for a List of Products:

public ActionResult Index()
{
    var model = new List<Product>();

    using(HttpClient client = new HttpClient())
    {
        model = client.GetAsync(uri).Result.Content.ReadAsAsync<List<Product>>().Result;
    }

    return View(model);
}

I am trying to unit test this, have tried using Telerik JustMock to test, for example:

[TestMethod]
    public void IndexDisplaysAllProducts()
    {                                       // Not sure how to call here
        var repo = Mock.Arrange(() => (new List<Product>())).Returns(
                new List<Product> { 
                    new Product(), 
                    new Product(), 
                    new Product()
                });

        var controller = new ProductsController();

        var result = (ViewResult)controller.Index();
        var model = (List<Product>)result.Model;

        Assert.AreEqual(3, model.Count);
    }

Just wondered how you would go about testing this?