content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 com.datastax.dse.driver.internal.core.cql.reactive;
  
  import static org.assertj.core.api.Fail.fail;
  
  import com.datastax.oss.driver.shaded.guava.common.util.concurrent.Uninterruptibles;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.TimeUnit;
  import org.reactivestreams.Subscriber;
  import org.reactivestreams.Subscription;
  
  public class TestSubscriber<T> implements Subscriber<T> {
  
    private final List<T> elements = new ArrayList<>();
    private final CountDownLatch latch = new CountDownLatch(1);
    private final long demand;
    private Subscription subscription;
    private Throwable error;
  
    public TestSubscriber() {
      this.demand = Long.MAX_VALUE;
    }
  
    public TestSubscriber(long demand) {
      this.demand = demand;
    }
  
    @Override
    public void onSubscribe(Subscription s) {
      if (subscription != null) {
        fail("already subscribed");
      }
      subscription = s;
      subscription.request(demand);
    }
  
    @Override
    public void onNext(T t) {
      elements.add(t);
    }
  
    @Override
    public void onError(Throwable t) {
      error = t;
      latch.countDown();
    }
  
    @Override
    public void onComplete() {
      latch.countDown();
    }
  
    @Nullable
    public Throwable getError() {
      return error;
    }
  
    @NonNull
    public List<T> getElements() {
      return elements;
    }
  
    public void awaitTermination() {
      if (!Uninterruptibles.awaitUninterruptibly(latch, 1, TimeUnit.MINUTES)) {
        fail("subscriber not terminated");
      }
    }
  }
  