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 static org.junit.Assert.*;
  
  import java.util.List;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.functions.Supplier;
  import io.reactivex.rxjava3.observable.ObservableCovarianceTest.*;
  
  public class ObservableMergeTests extends RxJavaTest {
  
      /**
       * This won't compile if super/extends isn't done correctly on generics.
       */
      @Test
      public void covarianceOfMerge() {
          Observable<HorrorMovie> horrors = Observable.just(new HorrorMovie());
          Observable<Observable<HorrorMovie>> metaHorrors = Observable.just(horrors);
          Observable.<Media> merge(metaHorrors);
      }
  
      @Test
      public void mergeCovariance() {
          Observable<Media> o1 = Observable.<Media> just(new HorrorMovie(), new Movie());
          Observable<Media> o2 = Observable.just(new Media(), new HorrorMovie());
  
          Observable<Observable<Media>> os = Observable.just(o1, o2);
  
          List<Media> values = Observable.merge(os).toList().blockingGet();
  
          assertEquals(4, values.size());
      }
  
      @Test
      public void mergeCovariance2() {
          Observable<Media> o1 = Observable.just(new HorrorMovie(), new Movie(), new Media());
          Observable<Media> o2 = Observable.just(new Media(), new HorrorMovie());
  
          Observable<Observable<Media>> os = Observable.just(o1, o2);
  
          List<Media> values = Observable.merge(os).toList().blockingGet();
  
          assertEquals(5, values.size());
      }
  
      @Test
      public void mergeCovariance3() {
          Observable<Movie> o1 = Observable.just(new HorrorMovie(), new Movie());
          Observable<Media> o2 = Observable.just(new Media(), new HorrorMovie());
  
          List<Media> values = Observable.merge(o1, o2).toList().blockingGet();
  
          assertTrue(values.get(0) instanceof HorrorMovie);
          assertTrue(values.get(1) instanceof Movie);
          assertNotNull(values.get(2));
          assertTrue(values.get(3) instanceof HorrorMovie);
      }
  
      @Test
      public void mergeCovariance4() {
  
          Observable<Movie> o1 = Observable.defer(new Supplier<Observable<Movie>>() {
              @Override
              public Observable<Movie> get() {
                  return Observable.just(
                          new HorrorMovie(),
                          new Movie()
                  );
              }
          });
  
          Observable<Media> o2 = Observable.just(new Media(), new HorrorMovie());
  
          List<Media> values = Observable.merge(o1, o2).toList().blockingGet();
  
          assertTrue(values.get(0) instanceof HorrorMovie);
          assertTrue(values.get(1) instanceof Movie);
          assertNotNull(values.get(2));
          assertTrue(values.get(3) instanceof HorrorMovie);
      }
  
  }
  