Basic react-router 4 setup for login and protected routes.
Assuming there is a UserStore that can perform the actual operations. It also provides a user prop to pages when the user is logged in.
Omitting any insiginificant import statements. This is not copy-pastable code, but still real-world code. (Omitted some project/ui-specific stuff)
Renders the App, but wrapped in a Router. That way we can use Route and Switch components anywhere in our app tree.