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.mockito.ArgumentMatchers.*;
  import static org.mockito.Mockito.*;
  
  import java.io.IOException;
  import java.util.List;
  
  import io.reactivex.rxjava3.disposables.Disposable;
  import org.junit.*;
  import org.mockito.InOrder;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.observers.TestObserver;
  import io.reactivex.rxjava3.operators.QueueFuseable;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  import io.reactivex.rxjava3.subjects.*;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class ObservableDistinctUntilChangedTest extends RxJavaTest {
  
      Observer<String> w;
      Observer<String> w2;
  
      // nulls lead to exceptions
      final Function<String, String> TO_UPPER_WITH_EXCEPTION = new Function<String, String>() {
          @Override
          public String apply(String s) {
              if (s.equals("x")) {
                  return "xx";
              }
              return s.toUpperCase();
          }
      };
  
      @Before
      public void before() {
          w = TestHelper.mockObserver();
          w2 = TestHelper.mockObserver();
      }
  
      @Test
      public void distinctUntilChangedOfNone() {
          Observable<String> src = Observable.empty();
          src.distinctUntilChanged().subscribe(w);
  
          verify(w, never()).onNext(anyString());
          verify(w, never()).onError(any(Throwable.class));
          verify(w, times(1)).onComplete();
      }
  
      @Test
      public void distinctUntilChangedOfNoneWithKeySelector() {
          Observable<String> src = Observable.empty();
          src.distinctUntilChanged(TO_UPPER_WITH_EXCEPTION).subscribe(w);
  
          verify(w, never()).onNext(anyString());
          verify(w, never()).onError(any(Throwable.class));
          verify(w, times(1)).onComplete();
      }
  
      @Test
      public void distinctUntilChangedOfNormalSource() {
          Observable<String> src = Observable.just("a", "b", "c", "c", "c", "b", "b", "a", "e");
          src.distinctUntilChanged().subscribe(w);
  
          InOrder inOrder = inOrder(w);
          inOrder.verify(w, times(1)).onNext("a");
          inOrder.verify(w, times(1)).onNext("b");
          inOrder.verify(w, times(1)).onNext("c");
          inOrder.verify(w, times(1)).onNext("b");
          inOrder.verify(w, times(1)).onNext("a");
          inOrder.verify(w, times(1)).onNext("e");
          inOrder.verify(w, times(1)).onComplete();
          inOrder.verify(w, never()).onNext(anyString());
          verify(w, never()).onError(any(Throwable.class));
      }
  
      @Test
      public void distinctUntilChangedOfNormalSourceWithKeySelector() {
          Observable<String> src = Observable.just("a", "b", "c", "C", "c", "B", "b", "a", "e");
          src.distinctUntilChanged(TO_UPPER_WITH_EXCEPTION).subscribe(w);
  
          InOrder inOrder = inOrder(w);
          inOrder.verify(w, times(1)).onNext("a");
          inOrder.verify(w, times(1)).onNext("b");
          inOrder.verify(w, times(1)).onNext("c");
          inOrder.verify(w, times(1)).onNext("B");
          inOrder.verify(w, times(1)).onNext("a");
          inOrder.verify(w, times(1)).onNext("e");
          inOrder.verify(w, times(1)).onComplete();
          inOrder.verify(w, never()).onNext(anyString());
          verify(w, never()).onError(any(Throwable.class));
      }
  
      @Test
      public void customComparator() {
          Observable<String> source = Observable.just("a", "b", "B", "A", "a", "C");
  
          TestObserver<String> to = TestObserver.create();
  
          source.distinctUntilChanged(new BiPredicate<String, String>() {
              @Override
              public boolean test(String a, String b) {
                  return a.compareToIgnoreCase(b) == 0;
              }
          })
          .subscribe(to);
  
          to.assertValues("a", "b", "A", "C");
          to.assertNoErrors();
          to.assertComplete();
      }
  
      @Test
      public void customComparatorThrows() {
          Observable<String> source = Observable.just("a", "b", "B", "A", "a", "C");
  
          TestObserver<String> to = TestObserver.create();
  
          source.distinctUntilChanged(new BiPredicate<String, String>() {
              @Override
              public boolean test(String a, String b) {
                  throw new TestException();
              }
          })
          .subscribe(to);
  
          to.assertValue("a");
          to.assertNotComplete();
          to.assertError(TestException.class);
      }
  
      @Test
      public void fused() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
          Observable.just(1, 2, 2, 3, 3, 4, 5)
          .distinctUntilChanged(new BiPredicate<Integer, Integer>() {
              @Override
              public boolean test(Integer a, Integer b) throws Exception {
                  return a.equals(b);
              }
          })
          .subscribe(to);
  
          to.assertFuseable()
          .assertFusionMode(QueueFuseable.SYNC)
          .assertResult(1, 2, 3, 4, 5)
          ;
      }
  
      @Test
      public void fusedAsync() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
          UnicastSubject<Integer> us = UnicastSubject.create();
  
          us
          .distinctUntilChanged(new BiPredicate<Integer, Integer>() {
              @Override
              public boolean test(Integer a, Integer b) throws Exception {
                  return a.equals(b);
              }
          })
          .subscribe(to);
  
          TestHelper.emit(us, 1, 2, 2, 3, 3, 4, 5);
  
          to.assertFuseable()
          .assertFusionMode(QueueFuseable.ASYNC)
          .assertResult(1, 2, 3, 4, 5)
          ;
      }
  
      @Test
      public void ignoreCancel() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
  
          try {
              Observable.wrap(new ObservableSource<Integer>() {
                  @Override
                  public void subscribe(Observer<? super Integer> observer) {
                      observer.onSubscribe(Disposable.empty());
                      observer.onNext(1);
                      observer.onNext(2);
                      observer.onNext(3);
                      observer.onError(new IOException());
                      observer.onComplete();
                  }
              })
              .distinctUntilChanged(new BiPredicate<Integer, Integer>() {
                  @Override
                  public boolean test(Integer a, Integer b) throws Exception {
                      throw new TestException();
                  }
              })
              .test()
              .assertFailure(TestException.class, 1);
  
              TestHelper.assertUndeliverable(errors, 0, IOException.class);
          } finally {
              RxJavaPlugins.reset();
          }
     }
  
      class Mutable {
          int value;
      }
  
      @Test
      public void mutableWithSelector() {
          Mutable m = new Mutable();
  
          PublishSubject<Mutable> ps = PublishSubject.create();
  
          TestObserver<Mutable> to = ps.distinctUntilChanged(new Function<Mutable, Object>() {
              @Override
              public Object apply(Mutable m) throws Exception {
                  return m.value;
              }
          })
          .test();
  
          ps.onNext(m);
          m.value = 1;
          ps.onNext(m);
          ps.onComplete();
  
          to.assertResult(m, m);
      }
  }
  