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.any;
  import static org.mockito.Mockito.*;
  
  import org.junit.Test;
  import org.mockito.Mockito;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.internal.functions.Functions;
  import io.reactivex.rxjava3.operators.QueueFuseable;
  import io.reactivex.rxjava3.subjects.UnicastSubject;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class ObservableFilterTest extends RxJavaTest {
  
      @Test
      public void filter() {
          Observable<String> w = Observable.just("one", "two", "three");
          Observable<String> observable = w.filter(new Predicate<String>() {
  
              @Override
              public boolean test(String t1) {
                  return t1.equals("two");
              }
          });
  
          Observer<String> observer = TestHelper.mockObserver();
  
          observable.subscribe(observer);
  
          verify(observer, Mockito.never()).onNext("one");
          verify(observer, times(1)).onNext("two");
          verify(observer, Mockito.never()).onNext("three");
          verify(observer, Mockito.never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Observable.range(1, 5).filter(Functions.alwaysTrue()));
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeObservable(new Function<Observable<Object>, ObservableSource<Object>>() {
              @Override
              public ObservableSource<Object> apply(Observable<Object> o) throws Exception {
                  return o.filter(Functions.alwaysTrue());
              }
          });
      }
  
      @Test
      public void fusedSync() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
          Observable.range(1, 5)
          .filter(new Predicate<Integer>() {
              @Override
              public boolean test(Integer v) throws Exception {
                  return v % 2 == 0;
              }
          })
          .subscribe(to);
  
          to.assertFusionMode(QueueFuseable.SYNC)
          .assertResult(2, 4);
      }
  
      @Test
      public void fusedAsync() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
          UnicastSubject<Integer> us = UnicastSubject.create();
  
          us
          .filter(new Predicate<Integer>() {
              @Override
              public boolean test(Integer v) throws Exception {
                  return v % 2 == 0;
              }
          })
          .subscribe(to);
  
          TestHelper.emit(us, 1, 2, 3, 4, 5);
  
          to.assertFusionMode(QueueFuseable.ASYNC)
          .assertResult(2, 4);
      }
  
      @Test
      public void fusedReject() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY | QueueFuseable.BOUNDARY);
  
          Observable.range(1, 5)
          .filter(new Predicate<Integer>() {
              @Override
              public boolean test(Integer v) throws Exception {
                  return v % 2 == 0;
              }
          })
          .subscribe(to);
  
          to.assertFusionMode(QueueFuseable.NONE)
          .assertResult(2, 4);
      }
  
      @Test
      public void filterThrows() {
          Observable.range(1, 5)
          .filter(new Predicate<Integer>() {
              @Override
              public boolean test(Integer v) throws Exception {
                  throw new TestException();
              }
          })
          .test()
          .assertFailure(TestException.class);
      }
  }
  