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.observers;
  
  import static org.junit.Assert.*;
  
  import java.util.List;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.*;
  import io.reactivex.rxjava3.exceptions.*;
  import io.reactivex.rxjava3.observers.TestObserver;
  import io.reactivex.rxjava3.operators.QueueDisposable;
  import io.reactivex.rxjava3.operators.QueueFuseable;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class DeferredScalarObserverTest extends RxJavaTest {
  
      static final class TakeFirst extends DeferredScalarObserver<Integer, Integer> {
  
          private static final long serialVersionUID = -2793723002312330530L;
  
          TakeFirst(Observer<? super Integer> downstream) {
              super(downstream);
          }
  
          @Override
          public void onNext(Integer value) {
              upstream.dispose();
              complete(value);
              complete(value);
          }
  
      }
  
      @Test
      public void normal() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserver<Integer> to = new TestObserver<>();
  
              TakeFirst source = new TakeFirst(to);
  
              source.onSubscribe(Disposable.empty());
  
              Disposable d = Disposable.empty();
              source.onSubscribe(d);
  
              assertTrue(d.isDisposed());
  
              source.onNext(1);
  
              to.assertResult(1);
  
              TestHelper.assertError(errors, 0, ProtocolViolationException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void error() {
          TestObserver<Integer> to = new TestObserver<>();
  
          TakeFirst source = new TakeFirst(to);
  
          source.onSubscribe(Disposable.empty());
          source.onError(new TestException());
  
          to.assertFailure(TestException.class);
      }
  
      @Test
      public void complete() {
          TestObserver<Integer> to = new TestObserver<>();
  
          TakeFirst source = new TakeFirst(to);
  
          source.onSubscribe(Disposable.empty());
          source.onComplete();
  
          to.assertResult();
      }
  
      @Test
      public void dispose() {
          TestObserver<Integer> to = new TestObserver<>();
  
          TakeFirst source = new TakeFirst(to);
  
          Disposable d = Disposable.empty();
  
          source.onSubscribe(d);
  
          assertFalse(d.isDisposed());
  
          to.dispose();
  
          assertTrue(d.isDisposed());
  
          assertTrue(source.isDisposed());
      }
  
      @Test
      public void fused() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
              TakeFirst source = new TakeFirst(to);
  
              Disposable d = Disposable.empty();
  
              source.onSubscribe(d);
  
              to.assertFuseable();
              to.assertFusionMode(QueueFuseable.ASYNC);
  
              source.onNext(1);
              source.onNext(1);
              source.onError(new TestException());
              source.onComplete();
  
              assertTrue(d.isDisposed());
  
              to.assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void fusedReject() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.SYNC);
  
              TakeFirst source = new TakeFirst(to);
  
              Disposable d = Disposable.empty();
  
              source.onSubscribe(d);
  
              to.assertFuseable();
              to.assertFusionMode(QueueFuseable.NONE);
  
              source.onNext(1);
              source.onNext(1);
              source.onError(new TestException());
              source.onComplete();
  
              assertTrue(d.isDisposed());
  
              to.assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      static final class TakeLast extends DeferredScalarObserver<Integer, Integer> {
  
          private static final long serialVersionUID = -2793723002312330530L;
  
          TakeLast(Observer<? super Integer> downstream) {
              super(downstream);
          }
  
          @Override
          public void onNext(Integer value) {
              this.value = value;
          }
  
      }
  
      @Test
      public void nonfusedTerminateMore() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.NONE);
  
              TakeLast source = new TakeLast(to);
  
              Disposable d = Disposable.empty();
  
              source.onSubscribe(d);
  
              source.onNext(1);
              source.onComplete();
              source.onComplete();
              source.onError(new TestException());
  
              to.assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void nonfusedError() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.NONE);
  
              TakeLast source = new TakeLast(to);
  
              Disposable d = Disposable.empty();
  
              source.onSubscribe(d);
  
              source.onNext(1);
              source.onError(new TestException());
              source.onError(new TestException("second"));
              source.onComplete();
  
              to.assertFailure(TestException.class);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class, "second");
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void fusedTerminateMore() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
              TakeLast source = new TakeLast(to);
  
              Disposable d = Disposable.empty();
  
              source.onSubscribe(d);
  
              source.onNext(1);
              source.onComplete();
              source.onComplete();
              source.onError(new TestException());
  
              to.assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void fusedError() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
              TakeLast source = new TakeLast(to);
  
              Disposable d = Disposable.empty();
  
              source.onSubscribe(d);
  
              source.onNext(1);
              source.onError(new TestException());
              source.onError(new TestException("second"));
              source.onComplete();
  
              to.assertFailure(TestException.class);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class, "second");
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void disposed() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.NONE);
  
          TakeLast source = new TakeLast(to);
  
          Disposable d = Disposable.empty();
  
          source.onSubscribe(d);
  
          to.dispose();
  
          source.onNext(1);
          source.onComplete();
  
          to.assertNoValues().assertNoErrors().assertNotComplete();
      }
  
      @Test
      public void disposedAfterOnNext() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          TakeLast source = new TakeLast(new Observer<Integer>() {
              Disposable upstream;
  
              @Override
              public void onSubscribe(Disposable d) {
                  this.upstream = d;
                  to.onSubscribe(d);
              }
  
              @Override
              public void onNext(Integer value) {
                  to.onNext(value);
                  upstream.dispose();
              }
  
              @Override
              public void onError(Throwable e) {
                  to.onError(e);
              }
  
              @Override
              public void onComplete() {
                  to.onComplete();
              }
          });
  
          source.onSubscribe(Disposable.empty());
          source.onNext(1);
          source.onComplete();
  
          to.assertValue(1).assertNoErrors().assertNotComplete();
      }
  
      @Test
      public void fusedEmpty() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.ANY);
  
          TakeLast source = new TakeLast(to);
  
          Disposable d = Disposable.empty();
  
          source.onSubscribe(d);
  
          source.onComplete();
  
          to.assertResult();
      }
  
      @Test
      public void nonfusedEmpty() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.NONE);
  
          TakeLast source = new TakeLast(to);
  
          Disposable d = Disposable.empty();
  
          source.onSubscribe(d);
  
          source.onComplete();
  
          to.assertResult();
      }
  
      @Test
      public void customFusion() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          TakeLast source = new TakeLast(new Observer<Integer>() {
              QueueDisposable<Integer> d;
  
              @SuppressWarnings("unchecked")
              @Override
              public void onSubscribe(Disposable d) {
                  this.d = (QueueDisposable<Integer>)d;
                  to.onSubscribe(d);
                  this.d.requestFusion(QueueFuseable.ANY);
              }
  
              @Override
              public void onNext(Integer value) {
                  if (!d.isEmpty()) {
                      Integer v = null;
                      try {
                          to.onNext(d.poll());
  
                          v = d.poll();
                      } catch (Throwable ex) {
                          to.onError(ex);
                      }
  
                      assertNull(v);
                      assertTrue(d.isEmpty());
                  }
              }
  
              @Override
              public void onError(Throwable e) {
                  to.onError(e);
              }
  
              @Override
              public void onComplete() {
                  to.onComplete();
              }
          });
  
          source.onSubscribe(Disposable.empty());
          source.onNext(1);
          source.onComplete();
  
          to.assertResult(1);
      }
  
      @Test
      public void customFusionClear() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          TakeLast source = new TakeLast(new Observer<Integer>() {
              QueueDisposable<Integer> d;
  
              @SuppressWarnings("unchecked")
              @Override
              public void onSubscribe(Disposable d) {
                  this.d = (QueueDisposable<Integer>)d;
                  to.onSubscribe(d);
                  this.d.requestFusion(QueueFuseable.ANY);
              }
  
              @Override
              public void onNext(Integer value) {
                  d.clear();
                  assertTrue(d.isEmpty());
              }
  
              @Override
              public void onError(Throwable e) {
                  to.onError(e);
              }
  
              @Override
              public void onComplete() {
                  to.onComplete();
              }
          });
  
          source.onSubscribe(Disposable.empty());
          source.onNext(1);
          source.onComplete();
  
          to.assertNoValues().assertNoErrors().assertComplete();
      }
  
      @Test
      public void offerThrow() {
          TestObserverEx<Integer> to = new TestObserverEx<>(QueueFuseable.NONE);
  
          TakeLast source = new TakeLast(to);
  
          TestHelper.assertNoOffer(source);
      }
  
      @Test
      public void customFusionDontConsume() {
          final TestObserver<Integer> to = new TestObserver<>();
  
          TakeFirst source = new TakeFirst(new Observer<Integer>() {
              QueueDisposable<Integer> d;
  
              @SuppressWarnings("unchecked")
              @Override
              public void onSubscribe(Disposable d) {
                  this.d = (QueueDisposable<Integer>)d;
                  to.onSubscribe(d);
                  this.d.requestFusion(QueueFuseable.ANY);
              }
  
              @Override
              public void onNext(Integer value) {
                  // not consuming
              }
  
              @Override
              public void onError(Throwable e) {
                  to.onError(e);
              }
  
              @Override
              public void onComplete() {
                  to.onComplete();
              }
          });
  
          source.onSubscribe(Disposable.empty());
          source.onNext(1);
  
          to.assertNoValues().assertNoErrors().assertComplete();
      }
  
  }
  