When testing software-based products, UI testing is just as important as unit testing. Both types of testing allow the tester to evaluate an application as a whole rather than evaluate individual components. It is possible to do this using C# UI testing frameworks. A C# UI testing framework provides classes and methods for executing tests that verify not only the parts but also the user interface of an application.
It can be difficult to accurately test behavior across multiple browsers and platforms. You can use C# UI Testing Open Source libraries to help with this process. EasyRepro - Automated UI testing API for Dynamics 365; unity-uitest - Unity UI Test Automation Framework; Tellerium - A utility pack to create maintainable UI tests using Selenium with additional support for ASP.NET MVC projects.