Category: Toolkit

This article is part of the MVVM – Made Easy series, focusing on handling UI events with ViewModel commands.

This series comprises articles that provide insights into working with the MVVM design pattern, to make it a delightful experience. All the articles in this series can be accessed from here – MVVM – Made Easy

The View serves as the user interface, while the ViewModel is composed of Properties and Commands that encapsulate the underlying logic. This architectural layering offers the distinct advantage of enabling independent development and testing of both components. Data Binding functions as the cohesive element that interlinks these two layers.

An event represents a significant mechanism for notifying state changes, such as a button click, to other components that have a vested interest in the occurrence.

The receiver component is capable of responding to the event by subscribing to it through a method whose signature corresponds with the delegate of the event ensuring type safety. And that method is generally referred to as an event handler.

However, the challenge emerges during the testing of the ViewModel, as the event is closely intertwined with the View. Business logic can’t be independently tested.