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tl;dr https://xunit.net/docs/getting-started/netcore/visual-studio
Existing Projects
Basic usage of the existing testing projects requires no special setup, as they were created as xUnit test projects in the first place; review the xUnit documentation for detail-in-depth.
Creating a New Project
If a new testing project for Windows/C# needs to be created, visit the the “Getting Started” link above for a quick and simple jumping-off point.