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.flowable;
  
  import static org.junit.Assert.*;
  
  import java.util.*;
  
  import io.reactivex.rxjava3.disposables.Disposable;
  import org.junit.Test;
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.core.Observable;
  import io.reactivex.rxjava3.core.Observer;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.internal.subscriptions.BooleanSubscription;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  import io.reactivex.rxjava3.processors.PublishProcessor;
  import io.reactivex.rxjava3.testsupport.TestHelper;
  
  public class FlowableElementAtTest extends RxJavaTest {
  
      @Test
      public void elementAtFlowable() {
          assertEquals(2, Flowable.fromArray(1, 2).elementAt(1).toFlowable().blockingSingle()
                  .intValue());
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void elementAtWithMinusIndexFlowable() {
          Flowable.fromArray(1, 2).elementAt(-1);
      }
  
      @Test
      public void elementAtWithIndexOutOfBoundsFlowable() {
          assertEquals(-100, Flowable.fromArray(1, 2).elementAt(2).toFlowable().blockingFirst(-100).intValue());
      }
  
      @Test
      public void elementAtOrDefaultFlowable() {
          assertEquals(2, Flowable.fromArray(1, 2).elementAt(1, 0).toFlowable().blockingSingle().intValue());
      }
  
      @Test
      public void elementAtOrDefaultWithIndexOutOfBoundsFlowable() {
          assertEquals(0, Flowable.fromArray(1, 2).elementAt(2, 0).toFlowable().blockingSingle().intValue());
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void elementAtOrDefaultWithMinusIndexFlowable() {
          Flowable.fromArray(1, 2).elementAt(-1, 0);
      }
  
      @Test
      public void elementAt() {
          assertEquals(2, Flowable.fromArray(1, 2).elementAt(1).blockingGet()
                  .intValue());
      }
  
      @Test
      public void elementAtConstrainsUpstreamRequests() {
          final List<Long> requests = new ArrayList<>();
          Flowable.fromArray(1, 2, 3, 4)
              .doOnRequest(new LongConsumer() {
                  @Override
                  public void accept(long n) throws Throwable {
                      requests.add(n);
                  }
              })
              .elementAt(2)
              .blockingGet()
                  .intValue();
          assertEquals(Arrays.asList(3L), requests);
      }
  
      @Test
      public void elementAtWithDefaultConstrainsUpstreamRequests() {
          final List<Long> requests = new ArrayList<>();
          Flowable.fromArray(1, 2, 3, 4)
              .doOnRequest(new LongConsumer() {
                  @Override
                  public void accept(long n) throws Throwable {
                      requests.add(n);
                  }
              })
              .elementAt(2, 100)
              .blockingGet()
                  .intValue();
          assertEquals(Arrays.asList(3L), requests);
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void elementAtWithMinusIndex() {
          Flowable.fromArray(1, 2).elementAt(-1);
      }
  
      @Test
      public void elementAtWithIndexOutOfBounds() {
          assertNull(Flowable.fromArray(1, 2).elementAt(2).blockingGet());
      }
  
      @Test
      public void elementAtOrDefault() {
          assertEquals(2, Flowable.fromArray(1, 2).elementAt(1, 0).blockingGet().intValue());
      }
  
      @Test
      public void elementAtOrDefaultWithIndexOutOfBounds() {
          assertEquals(0, Flowable.fromArray(1, 2).elementAt(2, 0).blockingGet().intValue());
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void elementAtOrDefaultWithMinusIndex() {
          Flowable.fromArray(1, 2).elementAt(-1, 0);
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void elementAtOrErrorNegativeIndex() {
          Flowable.empty()
              .elementAtOrError(-1);
      }
  
      @Test
      public void elementAtOrErrorNoElement() {
          Flowable.empty()
              .elementAtOrError(0)
              .test()
              .assertNoValues()
              .assertError(NoSuchElementException.class);
      }
  
      @Test
      public void elementAtOrErrorOneElement() {
          Flowable.just(1)
              .elementAtOrError(0)
              .test()
              .assertNoErrors()
              .assertValue(1);
      }
  
      @Test
      public void elementAtOrErrorMultipleElements() {
          Flowable.just(1, 2, 3)
              .elementAtOrError(1)
              .test()
              .assertNoErrors()
              .assertValue(2);
      }
  
      @Test
      public void elementAtOrErrorInvalidIndex() {
          Flowable.just(1, 2, 3)
              .elementAtOrError(3)
              .test()
              .assertNoValues()
              .assertError(NoSuchElementException.class);
      }
  
      @Test
      public void elementAtOrErrorError() {
          Flowable.error(new RuntimeException("error"))
              .elementAtOrError(0)
              .to(TestHelper.testConsumer())
              .assertNoValues()
              .assertErrorMessage("error")
              .assertError(RuntimeException.class);
      }
  
      @Test
      public void elementAtIndex0OnEmptySource() {
          Flowable.empty()
              .elementAt(0)
              .test()
              .assertResult();
      }
  
      @Test
      public void elementAtIndex0WithDefaultOnEmptySource() {
          Flowable.empty()
              .elementAt(0, 5)
              .test()
              .assertResult(5);
      }
  
      @Test
      public void elementAtIndex1OnEmptySource() {
          Flowable.empty()
              .elementAt(1)
              .test()
              .assertResult();
      }
  
      @Test
      public void elementAtIndex1WithDefaultOnEmptySource() {
          Flowable.empty()
              .elementAt(1, 10)
              .test()
              .assertResult(10);
      }
  
      @Test
      public void elementAtOrErrorIndex1OnEmptySource() {
          Flowable.empty()
              .elementAtOrError(1)
              .test()
              .assertFailure(NoSuchElementException.class);
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeFlowable(new Function<Flowable<Object>, Publisher<Object>>() {
              @Override
              public Publisher<Object> apply(Flowable<Object> f) throws Exception {
                  return f.elementAt(0).toFlowable();
              }
          });
  
          TestHelper.checkDoubleOnSubscribeFlowableToMaybe(new Function<Flowable<Object>, Maybe<Object>>() {
              @Override
              public Maybe<Object> apply(Flowable<Object> f) throws Exception {
                  return f.elementAt(0);
              }
          });
  
          TestHelper.checkDoubleOnSubscribeFlowableToSingle(new Function<Flowable<Object>, Single<Object>>() {
              @Override
              public Single<Object> apply(Flowable<Object> f) throws Exception {
                  return f.elementAt(0, 1);
              }
          });
      }
  
      @Test
      public void elementAtIndex1WithDefaultOnEmptySourceObservable() {
          Flowable.empty()
              .elementAt(1, 10)
              .toFlowable()
              .test()
              .assertResult(10);
      }
  
      @Test
      public void errorFlowable() {
          Flowable.error(new TestException())
              .elementAt(1, 10)
              .toFlowable()
              .test()
              .assertFailure(TestException.class);
      }
  
      @Test
      public void error() {
          Flowable.error(new TestException())
              .elementAt(1, 10)
              .test()
              .assertFailure(TestException.class);
  
          Flowable.error(new TestException())
          .elementAt(1)
          .test()
          .assertFailure(TestException.class);
      }
  
      @Test
      public void badSource() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              new Flowable<Integer>() {
                  @Override
                  protected void subscribeActual(Subscriber<? super Integer> subscriber) {
                      subscriber.onSubscribe(new BooleanSubscription());
  
                      subscriber.onNext(1);
                      subscriber.onNext(2);
                      subscriber.onError(new TestException());
                      subscriber.onComplete();
                  }
              }
              .elementAt(0)
              .toFlowable()
              .test()
              .assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
  
          TestHelper.checkBadSourceFlowable(new Function<Flowable<Integer>, Object>() {
              @Override
              public Object apply(Flowable<Integer> f) throws Exception {
                  return f.elementAt(0);
              }
          }, false, null, 1);
  
          TestHelper.checkBadSourceFlowable(new Function<Flowable<Integer>, Object>() {
              @Override
              public Object apply(Flowable<Integer> f) throws Exception {
                  return f.elementAt(0, 1);
              }
          }, false, null, 1, 1);
  
          TestHelper.checkBadSourceFlowable(new Function<Flowable<Integer>, Object>() {
              @Override
              public Object apply(Flowable<Integer> f) throws Exception {
                  return f.elementAt(0).toFlowable();
              }
          }, false, null, 1);
  
          TestHelper.checkBadSourceFlowable(new Function<Flowable<Integer>, Object>() {
              @Override
              public Object apply(Flowable<Integer> f) throws Exception {
                  return f.elementAt(0, 1).toFlowable();
              }
          }, false, null, 1, 1);
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(PublishProcessor.create().elementAt(0).toFlowable());
          TestHelper.checkDisposed(PublishProcessor.create().elementAt(0, 1).toFlowable());
  
          TestHelper.checkDisposed(PublishProcessor.create().elementAt(0));
          TestHelper.checkDisposed(PublishProcessor.create().elementAt(0, 1));
      }
  
      @Test
      public void badSourceObservable() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              new Observable<Integer>() {
                  @Override
                  protected void subscribeActual(Observer<? super Integer> observer) {
                      observer.onSubscribe(Disposable.empty());
  
                      observer.onNext(1);
                      observer.onNext(2);
                      observer.onError(new TestException());
                      observer.onComplete();
                  }
              }
              .elementAt(0)
              .toFlowable()
              .test()
              .assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void badSource2() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              new Flowable<Integer>() {
                  @Override
                  protected void subscribeActual(Subscriber<? super Integer> subscriber) {
                      subscriber.onSubscribe(new BooleanSubscription());
  
                      subscriber.onNext(1);
                      subscriber.onNext(2);
                      subscriber.onError(new TestException());
                      subscriber.onComplete();
                  }
              }
              .elementAt(0, 1)
              .test()
              .assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  }
  