ServiceStack client with WebApplicationFactory<Program>

When making Integration tests for asp.net core MS docs say to use WebApplicationFactory<Program>.

So with my SS project using Identity auth I can do something like:

_factory = new WebApplicationFactory<Program>();
using var client = _factory.CreateClient();
var response = await client.GetAsync("/hello");
Assert.That(response.IsSuccessStatusCode);

The HttpClient that is returned can make requests but it’s not actually firing up the host with a port I don’t think. I guess it’s intercepting the requests under the hood.

How do I use the ServiceStack client to make test requests? I guess I need to specify it to use the HttpClient created by the factory.

I try variations of:

var ssClient = new JsonServiceClient(client.BaseAddress?.ToString() ?? "/");
ssClient.HttpClient = client;

var response2 = await ssClient.GetAsync(new Hello { Name = "World" });

But it appears to be trying to make http request to local machine.

I have tried adding:

services.AddJsonApiClient("http://localhost"); //the base address set by factory

and tried getting it from IoC but I can’t quite figure out how to make it work. Is it possible or am I going in the wrong direction?