NUnit is an open-source unit testing framework for C# that originated from the JUnit framework and is widely used for developing and executing tests with the .NET language. This tutorial provides a comprehensive guide for setting up the NUnit environment using Visual Studio 2019, detailing steps for installing and configuring NUnit, the NUnit Visual Studio Adapter, and Selenium WebDriver, which facilitates automation testing with C#. The tutorial covers installation methods via Visual Studio IDE and NuGet Package Manager, catering to both beginners and seasoned developers. It also showcases how NUnit's compatibility with automation suites like Selenium can expedite test case development through features such as annotations and Test Driven Development (TDD) support. Additionally, it highlights the benefits of using the Visual Studio Extension for automatic updates and offers insights into setting up Selenium WebDriver for cross-browser testing. The article concludes by emphasizing the utility of NUnit in writing and running tests in Microsoft .NET, as well as explaining the differences between NUnit and other frameworks like xUnit.