This is an example of an app using ViewModel. It’s fully tested with both unit and e2e tests. When it comes to unit testing, it follows the principle of “test your app, not the framework”. For e2e tests it uses Protractor, which btw, is very easy to test with if you know a few things on how it works (like everything is a promise) and how to structure your tests (i.e. use page objects abstractions).
Let me know if you have any questions or comments.