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.observable;
  
  import static org.junit.Assert.*;
  
  import java.util.List;
  import java.util.concurrent.*;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.*;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.functions.Functions;
  import io.reactivex.rxjava3.observers.TestObserver;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  import io.reactivex.rxjava3.schedulers.Schedulers;
  import io.reactivex.rxjava3.subjects.*;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class ObservableFlatMapSingleTest extends RxJavaTest {
  
      @Test
      public void normal() {
          Observable.range(1, 10)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(v);
              }
          })
          .test()
          .assertResult(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
      }
  
      @Test
      public void normalDelayError() {
          Observable.range(1, 10)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(v);
              }
          }, true)
          .test()
          .assertResult(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
      }
  
      @Test
      public void normalAsync() {
          TestObserverEx<Integer> to = Observable.range(1, 10)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(v).subscribeOn(Schedulers.computation());
              }
          })
          .to(TestHelper.<Integer>testConsumer())
          .awaitDone(5, TimeUnit.SECONDS)
          .assertSubscribed()
          .assertNoErrors()
          .assertComplete();
  
          TestHelper.assertValueSet(to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
      }
  
      @Test
      public void mapperThrowsObservable() {
          PublishSubject<Integer> ps = PublishSubject.create();
  
          TestObserver<Integer> to = ps
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  throw new TestException();
              }
          })
          .test();
  
          assertTrue(ps.hasObservers());
  
          ps.onNext(1);
  
          to.assertFailure(TestException.class);
  
          assertFalse(ps.hasObservers());
      }
  
      @Test
      public void mapperReturnsNullObservable() {
          PublishSubject<Integer> ps = PublishSubject.create();
  
          TestObserver<Integer> to = ps
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return null;
              }
          })
          .test();
  
          assertTrue(ps.hasObservers());
  
          ps.onNext(1);
  
          to.assertFailure(NullPointerException.class);
  
          assertFalse(ps.hasObservers());
      }
  
      @Test
      public void normalDelayErrorAll() {
          TestObserverEx<Integer> to = Observable.range(1, 10).concatWith(Observable.<Integer>error(new TestException()))
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.error(new TestException());
              }
          }, true)
          .to(TestHelper.<Integer>testConsumer())
          .assertFailure(CompositeException.class);
  
          List<Throwable> errors = TestHelper.compositeList(to.errors().get(0));
  
          for (int i = 0; i < 11; i++) {
              TestHelper.assertError(errors, i, TestException.class);
          }
      }
  
      @Test
      public void takeAsync() {
          TestObserverEx<Integer> to = Observable.range(1, 10)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(v).subscribeOn(Schedulers.computation());
              }
          })
          .take(2)
          .to(TestHelper.<Integer>testConsumer())
          .awaitDone(5, TimeUnit.SECONDS)
          .assertSubscribed()
          .assertValueCount(2)
          .assertNoErrors()
          .assertComplete();
  
          TestHelper.assertValueSet(to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
      }
  
      @Test
      public void take() {
          Observable.range(1, 10)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(v);
              }
          })
          .take(2)
          .test()
          .assertResult(1, 2);
      }
  
      @Test
      public void middleError() {
          Observable.fromArray(new String[]{"1", "a", "2"}).flatMapSingle(new Function<String, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(final String s) throws NumberFormatException {
                  //return Single.just(Integer.valueOf(s)); //This works
                  return Single.fromCallable(new Callable<Integer>() {
                      @Override
                      public Integer call() throws NumberFormatException {
                          return Integer.valueOf(s);
                      }
                  });
              }
          })
          .test()
          .assertFailure(NumberFormatException.class, 1);
      }
  
      @Test
      public void asyncFlatten() {
          Observable.range(1, 1000)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.just(1).subscribeOn(Schedulers.computation());
              }
          })
          .take(500)
          .to(TestHelper.<Integer>testConsumer())
          .awaitDone(5, TimeUnit.SECONDS)
          .assertSubscribed()
          .assertValueCount(500)
          .assertNoErrors()
          .assertComplete();
      }
  
      @Test
      public void successError() {
          final PublishSubject<Integer> ps = PublishSubject.create();
  
          TestObserver<Integer> to = Observable.range(1, 2)
          .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  if (v == 2) {
                      return ps.singleOrError();
                  }
                  return Single.error(new TestException());
              }
          }, true)
          .test();
  
          ps.onNext(1);
          ps.onComplete();
  
          to
          .assertFailure(TestException.class, 1);
      }
  
      @Test
      public void disposed() {
          TestHelper.checkDisposed(PublishSubject.<Integer>create().flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(Integer v) throws Exception {
                  return Single.<Integer>just(1);
              }
          }));
      }
  
      @Test
      public void innerSuccessCompletesAfterMain() {
          PublishSubject<Integer> ps = PublishSubject.create();
  
          TestObserver<Integer> to = Observable.just(1).flatMapSingle(Functions.justFunction(ps.singleOrError()))
          .test();
  
          ps.onNext(2);
          ps.onComplete();
  
          to
          .assertResult(2);
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeObservable(new Function<Observable<Object>, ObservableSource<Integer>>() {
              @Override
              public ObservableSource<Integer> apply(Observable<Object> f) throws Exception {
                  return f.flatMapSingle(Functions.justFunction(Single.just(2)));
              }
          });
      }
  
      @Test
      public void badSource() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              new Observable<Integer>() {
                  @Override
                  protected void subscribeActual(Observer<? super Integer> observer) {
                      observer.onSubscribe(Disposable.empty());
                      observer.onError(new TestException("First"));
                      observer.onError(new TestException("Second"));
                  }
              }
              .flatMapSingle(Functions.justFunction(Single.just(2)))
              .to(TestHelper.<Integer>testConsumer())
              .assertFailureAndMessage(TestException.class, "First");
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class, "Second");
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void badInnerSource() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              Observable.just(1)
              .flatMapSingle(Functions.justFunction(new Single<Integer>() {
                  @Override
                  protected void subscribeActual(SingleObserver<? super Integer> observer) {
                      observer.onSubscribe(Disposable.empty());
                      observer.onError(new TestException("First"));
                      observer.onError(new TestException("Second"));
                  }
              }))
              .to(TestHelper.<Integer>testConsumer())
              .assertFailureAndMessage(TestException.class, "First");
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class, "Second");
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void emissionQueueTrigger() {
          final PublishSubject<Integer> ps1 = PublishSubject.create();
          final PublishSubject<Integer> ps2 = PublishSubject.create();
  
          TestObserver<Integer> to = new TestObserver<Integer>() {
              @Override
              public void onNext(Integer t) {
                  super.onNext(t);
                  if (t == 1) {
                      ps2.onNext(2);
                      ps2.onComplete();
                  }
              }
          };
  
          Observable.just(ps1, ps2)
                  .flatMapSingle(new Function<PublishSubject<Integer>, SingleSource<Integer>>() {
                      @Override
                      public SingleSource<Integer> apply(PublishSubject<Integer> v) throws Exception {
                          return v.singleOrError();
                      }
                  })
          .subscribe(to);
  
          ps1.onNext(1);
          ps1.onComplete();
  
          to.assertResult(1, 2);
      }
  
      @Test
      public void disposeInner() {
          final TestObserver<Object> to = new TestObserver<>();
  
          Observable.just(1).flatMapSingle(new Function<Integer, SingleSource<Object>>() {
              @Override
              public SingleSource<Object> apply(Integer v) throws Exception {
                  return new Single<Object>() {
                      @Override
                      protected void subscribeActual(SingleObserver<? super Object> observer) {
                          observer.onSubscribe(Disposable.empty());
  
                          assertFalse(((Disposable)observer).isDisposed());
  
                          to.dispose();
  
                          assertTrue(((Disposable)observer).isDisposed());
                      }
                  };
              }
          })
          .subscribe(to);
  
          to
          .assertEmpty();
      }
  
      @Test
      public void undeliverableUponCancel() {
          TestHelper.checkUndeliverableUponCancel(new ObservableConverter<Integer, Observable<Integer>>() {
              @Override
              public Observable<Integer> apply(Observable<Integer> upstream) {
                  return upstream.flatMapSingle(new Function<Integer, Single<Integer>>() {
                      @Override
                      public Single<Integer> apply(Integer v) throws Throwable {
                          return Single.just(v).hide();
                      }
                  });
              }
          });
      }
  
      @Test
      public void undeliverableUponCancelDelayError() {
          TestHelper.checkUndeliverableUponCancel(new ObservableConverter<Integer, Observable<Integer>>() {
              @Override
              public Observable<Integer> apply(Observable<Integer> upstream) {
                  return upstream.flatMapSingle(new Function<Integer, Single<Integer>>() {
                      @Override
                      public Single<Integer> apply(Integer v) throws Throwable {
                          return Single.just(v).hide();
                      }
                  }, true);
              }
          });
      }
  
      @Test
      public void innerErrorOuterCompleteRace() {
          TestException ex = new TestException();
          for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
              PublishSubject<Integer> ps1 = PublishSubject.create();
              SingleSubject<Integer> ps2 = SingleSubject.create();
  
              TestObserver<Integer> to = ps1.flatMapSingle(v -> ps2)
              .test();
  
              ps1.onNext(1);
  
              TestHelper.race(
                      () -> ps1.onComplete(),
                      () -> ps2.onError(ex)
              );
  
              to.assertFailure(TestException.class);
          }
      }
  
      @Test
      public void cancelWhileMapping() throws Throwable {
          for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
              PublishSubject<Integer> ps1 = PublishSubject.create();
  
              TestObserver<Integer> to = new TestObserver<>();
              CountDownLatch cdl = new CountDownLatch(1);
  
              ps1.flatMapSingle(v -> {
                  TestHelper.raceOther(() -> {
                      to.dispose();
                  }, cdl);
                  return Single.just(1);
              })
              .subscribe(to);
  
              ps1.onNext(1);
  
              cdl.await();
          }
      }
  
      @Test
      public void onNextDrainCancel() {
          SingleSubject<Integer> ss1 = SingleSubject.create();
          SingleSubject<Integer> ss2 = SingleSubject.create();
  
          TestObserver<Integer> to = new TestObserver<>();
  
          Observable.just(1, 2)
          .flatMapSingle(v -> v == 1 ? ss1 : ss2)
          .doOnNext(v -> {
              if (v == 1) {
                  ss2.onSuccess(2);
                  to.dispose();
              }
          })
          .subscribe(to);
  
          ss1.onSuccess(1);
  
          to.assertValuesOnly(1);
      }
  }
  