HttpClientExample.java

package tests;

import org.vertx.java.core.Handler;
import org.vertx.java.core.http.HttpServerRequest;
import org.vertx.java.core.http.RouteMatcher;
import org.vertx.java.deploy.Verticle;

public class HttpClientExample extends Verticle {

  public void start() {
		RouteMatcher rm = new RouteMatcher();
		rm.get("/", new Handler<HttpServerRequest>() {
			public void handle(HttpServerRequest request) {
				request.response.statusCode = 200;
				request.response.end("something");
			}
		});
		vertx.createHttpServer().requestHandler(rm).listen(8080);
	}

}

HttpClientTest.java

package tests;

import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.vertx.java.core.Handler;
import org.vertx.java.core.buffer.Buffer;
import org.vertx.java.core.http.HttpClient;
import org.vertx.java.core.http.HttpClientResponse;
import org.vertx.java.test.TestVerticle;
import org.vertx.java.test.VertxConfiguration;
import org.vertx.java.test.VertxTestBase;
import org.vertx.java.test.junit.VertxJUnit4ClassRunner;

@RunWith(VertxJUnit4ClassRunner.class)
@VertxConfiguration
@TestVerticle(main = "tests.HttpClientExample")
public class HttpClientTest extends VertxTestBase {

	private <T> void offer(T content, LinkedBlockingQueue<T> queue) {
		try {
			queue.offer(content, 10L, TimeUnit.SECONDS);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	@Test
	public void httpTest() {
		HttpClient client = getVertx().createHttpClient().setHost("localhost").setPort(8080);
		final LinkedBlockingQueue<HttpClientResponse> queueResponse = new LinkedBlockingQueue<>();
		final LinkedBlockingQueue<Buffer> queueBuffer = new LinkedBlockingQueue<>();
		client.getNow("/", new Handler<HttpClientResponse>() {
			@Override
			public void handle(HttpClientResponse event) {
				offer(event, queueResponse);
				event.bodyHandler(new Handler<Buffer>() {
					@Override
					public void handle(Buffer event) {
						offer(event, queueBuffer);
					}
				});
			}
		});

		try {
			HttpClientResponse answer1 = queueResponse.poll(10L, TimeUnit.SECONDS);
			if (answer1 == null) {
				fail("Did not receive answer1 in time.");
			}
			assertTrue("should get status code 200.", answer1.statusCode == 200);

			Buffer answer2 = queueBuffer.poll(10L, TimeUnit.SECONDS);

			if (answer2 == null) {
				fail("Did not receive answer2 in time.");
			}

			assertTrue("should receive 'something' but received: " + answer2.toString(), "something".equals(answer2.toString()));

		} catch (InterruptedException e) {
			//
		}
	}

}

QueueReplyHandler.java

/*
 * Copyright 2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package tests;

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;

import org.junit.Assert;
import org.vertx.java.core.Handler;

/**
 * @author swilliams
 *
 * @param <T>
 */
public class QueueReplyHandler<T> implements Handler<T> {

  private final LinkedBlockingQueue<T> queue;

  private final long timeout;

  private final TimeUnit timeUnit;

  public QueueReplyHandler(LinkedBlockingQueue<T> queue) {
    this(queue, 5000L);
  }

  public QueueReplyHandler(LinkedBlockingQueue<T> queue, long timeout) {
    this(queue, timeout, TimeUnit.MILLISECONDS);
  }

  public QueueReplyHandler(LinkedBlockingQueue<T> queue, long timeout, TimeUnit timeUnit) {
    this.queue = queue;
    this.timeout = timeout;
    this.timeUnit = timeUnit;
  }

  @Override
  public void handle(T event) {

    try {
      if (event != null) {
        queue.offer(event, timeout, timeUnit);
      }

    } catch (InterruptedException e) {
      Assert.fail(e.getMessage());
    }
  }
}

What you're doing here is illegal in Vert.x - vert.x objects e.g. HttpClientRequest HttpClientResponse etc must only be accessed on the context on which they're being created.

In this case you are getting a HttpResponse then transferring it back to the main thread where you are trying to do something with it.

Is this being run in a verticle?