code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * 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 io.reactivex.rxjava3.observable;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.observable.ObservableEventStream.Event;
  import io.reactivex.rxjava3.observables.GroupedObservable;
  
  public class ObservableGroupByTests extends RxJavaTest {
  
      @Test
      public void takeUnsubscribesOnGroupBy() throws Exception {
          Observable.merge(
              ObservableEventStream.getEventStream("HTTP-ClusterA", 50),
              ObservableEventStream.getEventStream("HTTP-ClusterB", 20)
          )
          // group by type (2 clusters)
          .groupBy(new Function<Event, String>() {
              @Override
              public String apply(Event event) {
                  return event.type;
              }
          })
          .take(1)
          .blockingForEach(new Consumer<GroupedObservable<String, Event>>() {
              @Override
              public void accept(GroupedObservable<String, Event> v) {
                  System.out.println(v);
                  v.take(1).subscribe();  // FIXME groups need consumption to a certain degree to cancel upstream
              }
          });
  
          System.out.println("**** finished");
  
          Thread.sleep(200); // make sure the event streams receive their interrupt
      }
  
      @Test
      public void takeUnsubscribesOnFlatMapOfGroupBy() throws Exception {
          Observable.merge(
              ObservableEventStream.getEventStream("HTTP-ClusterA", 50),
              ObservableEventStream.getEventStream("HTTP-ClusterB", 20)
          )
          // group by type (2 clusters)
          .groupBy(new Function<Event, String>() {
              @Override
              public String apply(Event event) {
                  return event.type;
              }
          })
          .flatMap(new Function<GroupedObservable<String, Event>, Observable<Object>>() {
              @Override
              public Observable<Object> apply(GroupedObservable<String, Event> g) {
                  return g.map(new Function<Event, Object>() {
                      @Override
                      public Object apply(Event event) {
                          return event.instanceId + " - " + event.values.get("count200");
                      }
                  });
              }
          })
          .take(20)
          .blockingForEach(new Consumer<Object>() {
              @Override
              public void accept(Object pv) {
                  System.out.println(pv);
              }
          });
  
          System.out.println("**** finished");
  
          Thread.sleep(200); // make sure the event streams receive their interrupt
      }
  }
  