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 static org.mockito.ArgumentMatchers.*;
  import static org.mockito.Mockito.*;
  
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicReference;
  
  import io.reactivex.rxjava3.functions.Action;
  import org.junit.*;
  import org.mockito.InOrder;
  import org.reactivestreams.Publisher;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.*;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.functions.Functions;
  import io.reactivex.rxjava3.internal.operators.observable.ObservableDebounceTimed.*;
  import io.reactivex.rxjava3.observers.TestObserver;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  import io.reactivex.rxjava3.schedulers.TestScheduler;
  import io.reactivex.rxjava3.subjects.*;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class ObservableDebounceTest extends RxJavaTest {
  
      private TestScheduler scheduler;
      private Observer<String> observer;
      private Scheduler.Worker innerScheduler;
  
      @Before
      public void before() {
          scheduler = new TestScheduler();
          observer = TestHelper.mockObserver();
          innerScheduler = scheduler.createWorker();
      }
  
      @Test
      public void debounceWithOnDroppedCallbackWithEx() throws Throwable {
          Observable<String> source = Observable.unsafeCreate(new ObservableSource<String>() {
              @Override
              public void subscribe(Observer<? super String> observer) {
                  observer.onSubscribe(Disposable.empty());
                  publishNext(observer, 100, "one");    // Should be skipped since "two" will arrive before the timeout expires.
                  publishNext(observer, 400, "two");    // Should be published since "three" will arrive after the timeout expires.
                  publishNext(observer, 900, "three");   // Should be skipped since onComplete will arrive before the timeout expires.
                  publishNext(observer, 999, "four");   // Should be skipped since onComplete will arrive before the timeout expires.
                  publishCompleted(observer, 1000);     // Should be published as soon as the timeout expires.
              }
          });
  
          Action whenDisposed = mock(Action.class);
          Observable<String> sampled = source
                  .doOnDispose(whenDisposed)
                  .debounce(400, TimeUnit.MILLISECONDS, scheduler, e -> {
              if ("three".equals(e)) {
                  throw new TestException("forced");
              }
          });
          sampled.subscribe(observer);
  
          scheduler.advanceTimeTo(0, TimeUnit.MILLISECONDS);
          InOrder inOrder = inOrder(observer);
          // must go to 800 since it must be 400 after when two is sent, which is at 400
          scheduler.advanceTimeTo(800, TimeUnit.MILLISECONDS);
          inOrder.verify(observer, times(1)).onNext("two");
          scheduler.advanceTimeTo(1000, TimeUnit.MILLISECONDS);
          inOrder.verify(observer, times(1)).onError(any(TestException.class));
          inOrder.verify(observer, never()).onNext("three");
          inOrder.verify(observer, never()).onNext("four");
          inOrder.verify(observer, never()).onComplete();
          inOrder.verifyNoMoreInteractions();
          verify(whenDisposed).run();
      }
  
      @Test
      public void debounceWithOnDroppedCallback() {
          Observable<String> source = Observable.unsafeCreate(new ObservableSource<String>() {
              @Override
              public void subscribe(Observer<? super String> observer) {
                  observer.onSubscribe(Disposable.empty());
                  publishNext(observer, 100, "one");    // Should be skipped since "two" will arrive before the timeout expires.
                  publishNext(observer, 400, "two");    // Should be published since "three" will arrive after the timeout expires.
                  publishNext(observer, 900, "three");   // Should be skipped since onComplete will arrive before the timeout expires.
                  publishNext(observer, 999, "four");   // Should be skipped since onComplete will arrive before the timeout expires.
                  publishCompleted(observer, 1000);     // Should be published as soon as the timeout expires.
              }
          });
  
          Observer<Object> drops = TestHelper.mockObserver();
          InOrder inOrderDrops = inOrder(drops);
          Observable<String> sampled = source.debounce(400, TimeUnit.MILLISECONDS, scheduler, drops::onNext);
          sampled.subscribe(observer);
  
          scheduler.advanceTimeTo(0, TimeUnit.MILLISECONDS);
          InOrder inOrder = inOrder(observer);
          // must go to 800 since it must be 400 after when two is sent, which is at 400
          scheduler.advanceTimeTo(800, TimeUnit.MILLISECONDS);
          inOrderDrops.verify(drops, times(1)).onNext("one");
          inOrder.verify(observer, times(1)).onNext("two");
          scheduler.advanceTimeTo(1000, TimeUnit.MILLISECONDS);
          inOrderDrops.verify(drops, times(1)).onNext("three");
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
          inOrderDrops.verifyNoMoreInteractions();
      }
  
      @Test
      public void debounceWithCompleted() {
          Observable<String> source = Observable.unsafeCreate(new ObservableSource<String>() {
              @Override
              public void subscribe(Observer<? super String> observer) {
                  observer.onSubscribe(Disposable.empty());
                  publishNext(observer, 100, "one");    // Should be skipped since "two" will arrive before the timeout expires.
                  publishNext(observer, 400, "two");    // Should be published since "three" will arrive after the timeout expires.
                  publishNext(observer, 900, "three");   // Should be skipped since onComplete will arrive before the timeout expires.
                  publishCompleted(observer, 1000);     // Should be published as soon as the timeout expires.
              }
          });
  
          Observable<String> sampled = source.debounce(400, TimeUnit.MILLISECONDS, scheduler);
          sampled.subscribe(observer);
  
          scheduler.advanceTimeTo(0, TimeUnit.MILLISECONDS);
          InOrder inOrder = inOrder(observer);
          // must go to 800 since it must be 400 after when two is sent, which is at 400
          scheduler.advanceTimeTo(800, TimeUnit.MILLISECONDS);
          inOrder.verify(observer, times(1)).onNext("two");
          scheduler.advanceTimeTo(1000, TimeUnit.MILLISECONDS);
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void debounceNeverEmits() {
          Observable<String> source = Observable.unsafeCreate(new ObservableSource<String>() {
              @Override
              public void subscribe(Observer<? super String> observer) {
                  observer.onSubscribe(Disposable.empty());
                  // all should be skipped since they are happening faster than the 200ms timeout
                  publishNext(observer, 100, "a");    // Should be skipped
                  publishNext(observer, 200, "b");    // Should be skipped
                  publishNext(observer, 300, "c");    // Should be skipped
                  publishNext(observer, 400, "d");    // Should be skipped
                  publishNext(observer, 500, "e");    // Should be skipped
                  publishNext(observer, 600, "f");    // Should be skipped
                  publishNext(observer, 700, "g");    // Should be skipped
                  publishNext(observer, 800, "h");    // Should be skipped
                  publishCompleted(observer, 900);     // Should be published as soon as the timeout expires.
              }
          });
  
          Observable<String> sampled = source.debounce(200, TimeUnit.MILLISECONDS, scheduler);
          sampled.subscribe(observer);
  
          scheduler.advanceTimeTo(0, TimeUnit.MILLISECONDS);
          InOrder inOrder = inOrder(observer);
          inOrder.verify(observer, times(0)).onNext(anyString());
          scheduler.advanceTimeTo(1000, TimeUnit.MILLISECONDS);
          inOrder.verify(observer, times(1)).onComplete();
          inOrder.verifyNoMoreInteractions();
      }
  
      @Test
      public void debounceWithError() {
          Observable<String> source = Observable.unsafeCreate(new ObservableSource<String>() {
              @Override
              public void subscribe(Observer<? super String> observer) {
                  observer.onSubscribe(Disposable.empty());
                  Exception error = new TestException();
                  publishNext(observer, 100, "one");    // Should be published since "two" will arrive after the timeout expires.
                  publishNext(observer, 600, "two");    // Should be skipped since onError will arrive before the timeout expires.
                  publishError(observer, 700, error);   // Should be published as soon as the timeout expires.
              }
          });
  
          Observable<String> sampled = source.debounce(400, TimeUnit.MILLISECONDS, scheduler);
          sampled.subscribe(observer);
  
          scheduler.advanceTimeTo(0, TimeUnit.MILLISECONDS);
          InOrder inOrder = inOrder(observer);
          // 100 + 400 means it triggers at 500
          scheduler.advanceTimeTo(500, TimeUnit.MILLISECONDS);
          inOrder.verify(observer).onNext("one");
          scheduler.advanceTimeTo(701, TimeUnit.MILLISECONDS);
          inOrder.verify(observer).onError(any(TestException.class));
          inOrder.verifyNoMoreInteractions();
      }
  
      private <T> void publishCompleted(final Observer<T> observer, long delay) {
          innerScheduler.schedule(new Runnable() {
              @Override
              public void run() {
                  observer.onComplete();
              }
          }, delay, TimeUnit.MILLISECONDS);
      }
  
      private <T> void publishError(final Observer<T> observer, long delay, final Exception error) {
          innerScheduler.schedule(new Runnable() {
              @Override
              public void run() {
                  observer.onError(error);
              }
          }, delay, TimeUnit.MILLISECONDS);
      }
  
      private <T> void publishNext(final Observer<T> observer, final long delay, final T value) {
          innerScheduler.schedule(new Runnable() {
              @Override
              public void run() {
                  observer.onNext(value);
              }
          }, delay, TimeUnit.MILLISECONDS);
      }
  
      @Test
      public void debounceSelectorNormal1() {
          PublishSubject<Integer> source = PublishSubject.create();
          final PublishSubject<Integer> debouncer = PublishSubject.create();
          Function<Integer, Observable<Integer>> debounceSel = new Function<Integer, Observable<Integer>>() {
  
              @Override
              public Observable<Integer> apply(Integer t1) {
                  return debouncer;
              }
          };
  
          Observer<Object> o = TestHelper.mockObserver();
          InOrder inOrder = inOrder(o);
  
          source.debounce(debounceSel).subscribe(o);
  
          source.onNext(1);
          debouncer.onNext(1);
  
          source.onNext(2);
          source.onNext(3);
          source.onNext(4);
  
          debouncer.onNext(2);
  
          source.onNext(5);
          source.onComplete();
  
          inOrder.verify(o).onNext(1);
          inOrder.verify(o).onNext(4);
          inOrder.verify(o).onNext(5);
          inOrder.verify(o).onComplete();
  
          verify(o, never()).onError(any(Throwable.class));
      }
  
      @Test
      public void debounceSelectorFuncThrows() {
          PublishSubject<Integer> source = PublishSubject.create();
          Function<Integer, Observable<Integer>> debounceSel = new Function<Integer, Observable<Integer>>() {
  
              @Override
              public Observable<Integer> apply(Integer t1) {
                  throw new TestException();
              }
          };
  
          Observer<Object> o = TestHelper.mockObserver();
  
          source.debounce(debounceSel).subscribe(o);
  
          source.onNext(1);
  
          verify(o, never()).onNext(any());
          verify(o, never()).onComplete();
          verify(o).onError(any(TestException.class));
      }
  
      @Test
      public void debounceSelectorObservableThrows() {
          PublishSubject<Integer> source = PublishSubject.create();
          Function<Integer, Observable<Integer>> debounceSel = new Function<Integer, Observable<Integer>>() {
  
              @Override
              public Observable<Integer> apply(Integer t1) {
                  return Observable.error(new TestException());
              }
          };
  
          Observer<Object> o = TestHelper.mockObserver();
  
          source.debounce(debounceSel).subscribe(o);
  
          source.onNext(1);
  
          verify(o, never()).onNext(any());
          verify(o, never()).onComplete();
          verify(o).onError(any(TestException.class));
      }
  
      @Test
      public void debounceTimedLastIsNotLost() {
          PublishSubject<Integer> source = PublishSubject.create();
  
          Observer<Object> o = TestHelper.mockObserver();
  
          source.debounce(100, TimeUnit.MILLISECONDS, scheduler).subscribe(o);
  
          source.onNext(1);
          source.onComplete();
  
          scheduler.advanceTimeBy(1, TimeUnit.SECONDS);
  
          verify(o).onNext(1);
          verify(o).onComplete();
          verify(o, never()).onError(any(Throwable.class));
      }
  
      @Test
      public void debounceSelectorLastIsNotLost() {
          PublishSubject<Integer> source = PublishSubject.create();
          final PublishSubject<Integer> debouncer = PublishSubject.create();
  
          Function<Integer, Observable<Integer>> debounceSel = new Function<Integer, Observable<Integer>>() {
  
              @Override
              public Observable<Integer> apply(Integer t1) {
                  return debouncer;
              }
          };
  
          Observer<Object> o = TestHelper.mockObserver();
  
          source.debounce(debounceSel).subscribe(o);
  
          source.onNext(1);
          source.onComplete();
  
          debouncer.onComplete();
  
          verify(o).onNext(1);
          verify(o).onComplete();
          verify(o, never()).onError(any(Throwable.class));
      }
  
      @Test
      public void debounceWithTimeBackpressure() throws InterruptedException {
          TestScheduler scheduler = new TestScheduler();
          TestObserverEx<Integer> observer = new TestObserverEx<>();
  
          Observable.merge(
                  Observable.just(1),
                  Observable.just(2).delay(10, TimeUnit.MILLISECONDS, scheduler)
          ).debounce(20, TimeUnit.MILLISECONDS, scheduler).take(1).subscribe(observer);
  
          scheduler.advanceTimeBy(30, TimeUnit.MILLISECONDS);
  
          observer.assertValue(2);
          observer.assertTerminated();
          observer.assertNoErrors();
      }
  
      @Test
      public void debounceDefault() throws Exception {
  
          Observable.just(1).debounce(1, TimeUnit.SECONDS)
          .test()
          .awaitDone(5, TimeUnit.SECONDS)
          .assertResult(1);
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(PublishSubject.create().debounce(1, TimeUnit.SECONDS, new TestScheduler()));
  
          TestHelper.checkDisposed(PublishSubject.create().debounce(Functions.justFunction(Observable.never())));
  
          Disposable d = new ObservableDebounceTimed.DebounceEmitter<>(1, 1, null);
          assertFalse(d.isDisposed());
  
          d.dispose();
  
          assertTrue(d.isDisposed());
      }
  
      @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.onComplete();
                      observer.onNext(1);
                      observer.onError(new TestException());
                      observer.onComplete();
                  }
              }
              .debounce(1, TimeUnit.SECONDS, new TestScheduler())
              .test()
              .assertResult();
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void badSourceSelector() {
          TestHelper.checkBadSourceObservable(new Function<Observable<Integer>, Object>() {
              @Override
              public Object apply(Observable<Integer> o) throws Exception {
                  return o.debounce(new Function<Integer, ObservableSource<Long>>() {
                      @Override
                      public ObservableSource<Long> apply(Integer v) throws Exception {
                          return Observable.timer(1, TimeUnit.SECONDS);
                      }
                  });
              }
          }, false, 1, 1, 1);
  
          TestHelper.checkBadSourceObservable(new Function<Observable<Integer>, Object>() {
              @Override
              public Object apply(final Observable<Integer> o) throws Exception {
                  return Observable.just(1).debounce(new Function<Integer, ObservableSource<Integer>>() {
                      @Override
                      public ObservableSource<Integer> apply(Integer v) throws Exception {
                          return o;
                      }
                  });
              }
          }, false, 1, 1, 1);
      }
  
      @Test
      public void debounceWithEmpty() {
          Observable.just(1).debounce(Functions.justFunction(Observable.empty()))
          .test()
          .assertResult(1);
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeObservable(new Function<Observable<Object>, Observable<Object>>() {
              @Override
              public Observable<Object> apply(Observable<Object> o) throws Exception {
                  return o.debounce(Functions.justFunction(Observable.never()));
              }
          });
      }
  
      @Test
      public void disposeInOnNext() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          BehaviorSubject.createDefault(1)
          .debounce(new Function<Integer, ObservableSource<Object>>() {
              @Override
              public ObservableSource<Object> apply(Integer o) throws Exception {
                  to.dispose();
                  return Observable.never();
              }
          })
          .subscribeWith(to)
          .assertEmpty();
  
          assertTrue(to.isDisposed());
      }
  
      @Test
      public void disposedInOnComplete() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          new Observable<Integer>() {
              @Override
              protected void subscribeActual(Observer<? super Integer> observer) {
                  observer.onSubscribe(Disposable.empty());
                  to.dispose();
                  observer.onComplete();
              }
          }
          .debounce(Functions.justFunction(Observable.never()))
          .subscribeWith(to)
          .assertEmpty();
      }
  
      @Test
      public void emitLate() {
          final AtomicReference<Observer<? super Integer>> ref = new AtomicReference<>();
  
          TestObserver<Integer> to = Observable.range(1, 2)
          .debounce(new Function<Integer, ObservableSource<Integer>>() {
              @Override
              public ObservableSource<Integer> apply(Integer o) throws Exception {
                  if (o != 1) {
                      return Observable.never();
                  }
                  return new Observable<Integer>() {
                      @Override
                      protected void subscribeActual(Observer<? super Integer> observer) {
                          observer.onSubscribe(Disposable.empty());
                          ref.set(observer);
                      }
                  };
              }
          })
          .test();
  
          ref.get().onNext(1);
  
          to
          .assertResult(2);
      }
  
      @Test
      public void timedDoubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeFlowable(new Function<Flowable<Object>, Publisher<Object>>() {
              @Override
              public Publisher<Object> apply(Flowable<Object> f)
                      throws Exception {
                  return f.debounce(1, TimeUnit.SECONDS);
              }
          });
      }
  
      @Test
      public void timedDisposedIgnoredBySource() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          new Observable<Integer>() {
              @Override
              protected void subscribeActual(
                      Observer<? super Integer> observer) {
                  observer.onSubscribe(Disposable.empty());
                  to.dispose();
                  observer.onNext(1);
                  observer.onComplete();
              }
          }
          .debounce(1, TimeUnit.SECONDS)
          .subscribe(to);
      }
  
      @Test
      public void timedLateEmit() {
          TestObserver<Integer> to = new TestObserver<>();
          DebounceTimedObserver<Integer> sub = new DebounceTimedObserver<>(
                  to, 1, TimeUnit.SECONDS, new TestScheduler().createWorker(), null);
  
          sub.onSubscribe(Disposable.empty());
  
          DebounceEmitter<Integer> de = new DebounceEmitter<>(1, 50, sub);
          de.run();
          de.run();
  
          to.assertEmpty();
      }
  
      @Test
      public void timedError() {
          Observable.error(new TestException())
          .debounce(1, TimeUnit.SECONDS)
          .test()
          .assertFailure(TestException.class);
      }
  
      @Test
      public void debounceOnEmpty() {
          Observable.empty().debounce(new Function<Object, ObservableSource<Object>>() {
              @Override
              public ObservableSource<Object> apply(Object o) {
                  return Observable.just(new Object());
              }
          }).subscribe();
      }
  
      @Test
      public void doubleOnSubscribeTime() {
          TestHelper.checkDoubleOnSubscribeObservable(o -> o.debounce(1, TimeUnit.SECONDS));
      }
  }
  