I have a sample server
var host = new WebHostBuilder() .UseKestrel() .UseContentRoot(Directory.GetCurrentDirectory())
XUnit starts the site from a different directory. We've had to work around it like this: https://github.com/aspnet/StaticFiles/blob/d692066b2bd711653150ad2cccc2268583355532/test/Microsoft.AspNetCore.StaticFiles.Tests/StaticFilesTestServer.cs#L20