Switch between native activities to web view activity from Espresso

Question

I am automating the login scenario using espresso. My scenario is:

1. I have to launch the activity
2. I need to select the env and details from app
3. Once clicking the login button, it automatically launches the browser for the login to the app

In this scenario first its launching the activity then after the click on the login button it is redirecting from the activity to the WebView.

How can I switch a native activity to an already opened WebView activity using espresso?