How can I create and run a webhost inside my test-libary?

I am currently working on a pretty simple test libary. The solution also contains an ASP.NET Core Webhost, which processes simple CRUD operations. I want to unit test this ASP.NET Core application without always having to start both projects, so I am creating a new WebHostBuilder inside my NUNit test-libary.

[OneTimeSetUp]
public void SetupHost()
{
    var webhostBuilder = new WebHostBuilder()
        .UseKestrel()
        .UseIISIntegration()
        .UseContentRoot("root")
        .UseStartup(typeof(Startup))
        .ConfigureAppConfiguration((builderContext, config) =>
        {
            config.AddJsonFile("config1", false);
            config.AddJsonFile("config2", false);
        });

    webhostBuilder
        .Build()
        .Run();
}

The problem is that SetupHost() never finishes, because Run() blocks the thread until the host shuts down.

How can I start a new webhost, then after it successfully started start my unit tests?