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.internal.operators.single;
  
  import static org.junit.Assert.*;
  
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.junit.Test;
  import org.reactivestreams.Publisher;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class SingleFlatMapTest extends RxJavaTest {
  
      @Test
      public void normal() {
          final boolean[] b = { false };
  
          Single.just(1)
          .flatMapCompletable(new Function<Integer, Completable>() {
              @Override
              public Completable apply(Integer t) throws Exception {
                  return Completable.complete().doOnComplete(new Action() {
                      @Override
                      public void run() throws Exception {
                          b[0] = true;
                      }
                  });
              }
          })
          .test()
          .assertResult();
  
          assertTrue(b[0]);
      }
  
      @Test
      public void error() {
          final boolean[] b = { false };
  
          Single.<Integer>error(new TestException())
          .flatMapCompletable(new Function<Integer, Completable>() {
              @Override
              public Completable apply(Integer t) throws Exception {
                  return Completable.complete().doOnComplete(new Action() {
                      @Override
                      public void run() throws Exception {
                          b[0] = true;
                      }
                  });
              }
          })
          .test()
          .assertFailure(TestException.class);
  
          assertFalse(b[0]);
      }
  
      @Test
      public void mapperThrows() {
          final boolean[] b = { false };
  
          Single.just(1)
          .flatMapCompletable(new Function<Integer, Completable>() {
              @Override
              public Completable apply(Integer t) throws Exception {
                  throw new TestException();
              }
          })
          .test()
          .assertFailure(TestException.class);
  
          assertFalse(b[0]);
      }
  
      @Test
      public void mapperReturnsNull() {
          final boolean[] b = { false };
  
          Single.just(1)
          .flatMapCompletable(new Function<Integer, Completable>() {
              @Override
              public Completable apply(Integer t) throws Exception {
                  return null;
              }
          })
          .test()
          .assertFailure(NullPointerException.class);
  
          assertFalse(b[0]);
      }
  
      @Test
      public void flatMapObservable() {
          Single.just(1).flatMapObservable(new Function<Integer, Observable<Integer>>() {
              @Override
              public Observable<Integer> apply(Integer v) throws Exception {
                  return Observable.range(v, 5);
              }
          })
          .test()
          .assertResult(1, 2, 3, 4, 5);
      }
  
      @Test
      public void flatMapPublisher() {
          Single.just(1).flatMapPublisher(new Function<Integer, Publisher<Integer>>() {
              @Override
              public Publisher<Integer> apply(Integer v) throws Exception {
                  return Flowable.range(v, 5);
              }
          })
          .test()
          .assertResult(1, 2, 3, 4, 5);
      }
  
      @Test
      public void flatMapPublisherMapperThrows() {
          final TestException ex = new TestException();
          Single.just(1)
          .flatMapPublisher(new Function<Integer, Publisher<Integer>>() {
              @Override
              public Publisher<Integer> apply(Integer v) throws Exception {
                  throw ex;
              }
          })
          .test()
          .assertNoValues()
          .assertError(ex);
      }
  
      @Test
      public void flatMapPublisherSingleError() {
          final TestException ex = new TestException();
          Single.<Integer>error(ex)
          .flatMapPublisher(new Function<Integer, Publisher<Integer>>() {
              @Override
              public Publisher<Integer> apply(Integer v) throws Exception {
                  return Flowable.just(1);
              }
          })
          .test()
          .assertNoValues()
          .assertError(ex);
      }
  
      @Test
      public void flatMapPublisherCancelDuringSingle() {
          final AtomicBoolean disposed = new AtomicBoolean();
          TestSubscriberEx<Integer> ts = Single.<Integer>never()
          .doOnDispose(new Action() {
              @Override
              public void run() throws Exception {
                  disposed.set(true);
              }
          })
          .flatMapPublisher(new Function<Integer, Publisher<Integer>>() {
              @Override
              public Publisher<Integer> apply(Integer v) throws Exception {
                  return Flowable.range(v, 5);
              }
          })
          .to(TestHelper.<Integer>testConsumer())
          .assertNoValues()
          .assertNotTerminated();
          assertFalse(disposed.get());
          ts.cancel();
          assertTrue(disposed.get());
          ts.assertNotTerminated();
      }
  
      @Test
      public void flatMapPublisherCancelDuringFlowable() {
          final AtomicBoolean disposed = new AtomicBoolean();
          TestSubscriberEx<Integer> ts =
          Single.just(1)
          .flatMapPublisher(new Function<Integer, Publisher<Integer>>() {
              @Override
              public Publisher<Integer> apply(Integer v) throws Exception {
                  return Flowable.<Integer>never()
                          .doOnCancel(new Action() {
                              @Override
                              public void run() throws Exception {
                                  disposed.set(true);
                              }
                          });
              }
          })
          .to(TestHelper.<Integer>testConsumer())
          .assertNoValues()
          .assertNotTerminated();
          assertFalse(disposed.get());
          ts.cancel();
          assertTrue(disposed.get());
          ts.assertNotTerminated();
      }
  
      @Test
      public void flatMapValue() {
          Single.just(1).flatMap(new Function<Integer, SingleSource<Integer>>() {
              @Override public SingleSource<Integer> apply(final Integer integer) throws Exception {
                  if (integer == 1) {
                      return Single.just(2);
                  }
  
                  return Single.just(1);
              }
          })
              .test()
              .assertResult(2);
      }
  
      @Test
      public void flatMapValueDifferentType() {
          Single.just(1).flatMap(new Function<Integer, SingleSource<String>>() {
              @Override public SingleSource<String> apply(final Integer integer) throws Exception {
                  if (integer == 1) {
                      return Single.just("2");
                  }
  
                  return Single.just("1");
              }
          })
              .test()
              .assertResult("2");
      }
  
      @Test
      public void flatMapValueNull() {
          Single.just(1).flatMap(new Function<Integer, SingleSource<Integer>>() {
              @Override public SingleSource<Integer> apply(final Integer integer) throws Exception {
                  return null;
              }
          })
          .to(TestHelper.<Integer>testConsumer())
              .assertNoValues()
              .assertError(NullPointerException.class)
              .assertErrorMessage("The single returned by the mapper is null");
      }
  
      @Test
      public void flatMapValueErrorThrown() {
          Single.just(1).flatMap(new Function<Integer, SingleSource<Integer>>() {
              @Override public SingleSource<Integer> apply(final Integer integer) throws Exception {
                  throw new RuntimeException("something went terribly wrong!");
              }
          })
              .to(TestHelper.<Integer>testConsumer())
              .assertNoValues()
              .assertError(RuntimeException.class)
              .assertErrorMessage("something went terribly wrong!");
      }
  
      @Test
      public void flatMapError() {
          RuntimeException exception = new RuntimeException("test");
  
          Single.error(exception).flatMap(new Function<Object, SingleSource<Object>>() {
              @Override public SingleSource<Object> apply(final Object integer) throws Exception {
                  return Single.just(new Object());
              }
          })
              .test()
              .assertError(exception);
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Single.just(1).flatMap(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(2);
              }
          }));
      }
  
      @Test
      public void mappedSingleOnError() {
          Single.just(1).flatMap(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.error(new TestException());
              }
          })
          .test()
          .assertFailure(TestException.class);
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeSingle(new Function<Single<Object>, SingleSource<Object>>() {
              @Override
              public SingleSource<Object> apply(Single<Object> s)
                      throws Exception {
                  return s.flatMap(new Function<Object, SingleSource<? extends Object>>() {
                      @Override
                      public SingleSource<? extends Object> apply(Object v)
                              throws Exception {
                          return Single.just(v);
                      }
                  });
              }
          });
      }
  }
  