Mini shopping cart A/B testing

I am working on integrating mini shopping cart in e-commerce website currently I am looking for some information/examples for best practices regarding this topic,So far it's obvious that it's a common practice that after adding an item to the cart a mini drop-down menu will appear to confirm that item has been added but what I'm missing A/B testing or Usability studied would be greate if you can provide some helpful links.

• Examples of case study: http://www.blueacorn.com/testing-the-mini-cart/

• Example of website has a mini cart feature https://www.gucci.com/de/de/