Android Espresso tests with rest api

I am currently testing my app's UI with Espresso, and have run into a few problems. My app requires a user to be logged in to use it, and then after logging in, in my apps onCreate I load a list with data that is retrieved from an api call to my server. How can i manually add this data(JSON) into my RecyclerView in my Espresso tests this way the app has data to work with during the testing.