In this tutorial, we are going to see how to unit test a view model in a Xamarin Forms application.
View Model in a Nutshell
The view model is the centerpiece of the Model-View-ViewModel pattern. When you're not using MVVM, your presentation logic is in the view (code behind), making harder to test because the logic is coupled to UI elements. On the other hand, when using MVVM, your presentation logic move into the view model, by decoupling logic from the view, you gain the ability to test logic without being bothered by UI elements.
Getting Started
To walk you through this tutorial, I created a Xamarin Forms app called WorkoutTube.