For information on using xUnit.net from within Visual Studio, see Running xUnit.net tests in Visual Studio.
The NuGet package manager GUI in Visual Studio (prior to 2015) does not let you
specify the version of a package you wish to install (or upgrade to). Since
there are later pre-release builds of the Visual Studio runner on NuGet.org,
you will need to use the Package Manager Console window inside Visual Studio
to install this build. To do so, show the console via
View > Other Windows > Package Manager Console, then type the
following command into the console window:
Update-Package xunit.runner.visualstudio -Version 2.0.1-rc1-build1078
This will update the Visual Studio runner package reference in all test projects in the currently open solution.