Example of using JerseyTest without extending it.

CompositionTest.java

import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.test.JerseyTest;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.core.Application;

import static org.assertj.core.api.Assertions.assertThat;


public class CompositionTest {

    @Path("test")
    public static class TestResource {
        @GET
        public String get() {
            return "Hello World!";
        }
    }

    private JerseyTest jerseyTest;

    @Before
    public void setUp() throws Exception {
        this.jerseyTest = new JerseyTest() {
            @Override
            protected Application configure() {
                return CompositionTest.this.configure();
            }
        };
        this.jerseyTest.setUp();
    }

    @After
    public void tearDown() throws Exception {
        this.jerseyTest.tearDown();
    }

    public ResourceConfig configure() {
        return new ResourceConfig(TestResource.class);
    }

    @Test
    public void doTest() {
        String response = this.jerseyTest.target("test")
                .request()
                .get(String.class);
        assertThat(response).isEqualTo("Hello World!");
    }
}