My apologies I wasn't too specific. I was meaning a controller through express. It's not as straightforward as you would expect with code buried throughout on how to set it up. This is a typical barrier for developers to not test as much.
Express doesn't even have controllers though -- just a routing mechanism.
If you set up your controllers so that they are independent from the routes, then they are just as easy to test.
It could be as simple as: app.get('/users/:id', userController.userPage). You can then test userController.userPage(req, res, next) instead of the route.
