DI Sample

product_controller.rb

class ProductController < ApplicationController

  def index
    @products = Product.all
  end

end

ProductController.cs

public class ProductController : Controller
{
    private IProductRepository _productRepository;

    public ProductController(IProductRepository productRepository)
    {
        _productRepository = productRepository;
    }

    public ActionResult Index()
    {
        products = productRepository.getAll();
        return View(products);
    }
}

This may be a perfectly good way to code it, and to test it. It's simple, I like it, and it'll probably do just fine. IMO, however, it is not Dependency Injection, simply because there is no injection going on.