adam bien's blog

@Path("/hello")
public class HelloResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "hello";
    }
}    

A dedicated quarkus project with installed MicroProfile REST Client extension (quarkus-rest-client) can be used as a testbed.

A proxy interface:

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import org.eclipse.microprofile.rest.client.inject.RegisterRestClient;

@RegisterRestClient(baseUri = "http://localhost:8080")
public interface HelloResource {

    @GET
    @Path("hello")
    @Produces(MediaType.TEXT_PLAIN)
    String content();    
}    

is injectable directly into the system test:

import static org.junit.jupiter.api.Assertions.assertEquals;
import javax.inject.Inject;
import org.eclipse.microprofile.rest.client.inject.RestClient;
import org.junit.jupiter.api.Test;

import io.quarkus.test.junit.QuarkusTest;

@QuarkusTest
public class HelloResourceTest {

    @Inject
    @RestClient
    HelloResource resource;

    @Test
    public void hello() {
        String content = resource.content();
        System.out.println(content);
        assertEquals(content,"hello");
    }
    
}    

See it live and from scratch: