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 java.util.*;
  import java.util.concurrent.*;
  
  import io.reactivex.rxjava3.disposables.Disposable;
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.core.Observable;
  import io.reactivex.rxjava3.core.Observer;
  import io.reactivex.rxjava3.exceptions.TestException;
  
  public class BlockingObservableToFutureTest extends RxJavaTest {
      @Test
      public void toFuture() throws InterruptedException, ExecutionException {
          Observable<String> obs = Observable.just("one");
          Future<String> f = obs.toFuture();
          assertEquals("one", f.get());
      }
  
      @Test
      public void toFutureList() throws InterruptedException, ExecutionException {
          Observable<String> obs = Observable.just("one", "two", "three");
          Future<List<String>> f = obs.toList().toFuture();
          assertEquals("one", f.get().get(0));
          assertEquals("two", f.get().get(1));
          assertEquals("three", f.get().get(2));
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void exceptionWithMoreThanOneElement() throws Throwable {
          Observable<String> obs = Observable.just("one", "two");
          Future<String> f = obs.toFuture();
          try {
              // we expect an exception since there are more than 1 element
              f.get();
              fail("Should have thrown!");
          }
          catch (ExecutionException e) {
              throw e.getCause();
          }
      }
  
      @Test
      public void toFutureWithException() {
          Observable<String> obs = Observable.unsafeCreate(new ObservableSource<String>() {
  
              @Override
              public void subscribe(Observer<? super String> observer) {
                  observer.onSubscribe(Disposable.empty());
                  observer.onNext("one");
                  observer.onError(new TestException());
              }
          });
  
          Future<String> f = obs.toFuture();
          try {
              f.get();
              fail("expected exception");
          } catch (Throwable e) {
              assertEquals(TestException.class, e.getCause().getClass());
          }
      }
  
      @Test(expected = CancellationException.class)
      public void getAfterCancel() throws Exception {
          Observable<String> obs = Observable.never();
          Future<String> f = obs.toFuture();
          boolean cancelled = f.cancel(true);
          assertTrue(cancelled);  // because OperationNeverComplete never does
          f.get();                // Future.get() docs require this to throw
      }
  
      @Test(expected = CancellationException.class)
      public void getWithTimeoutAfterCancel() throws Exception {
          Observable<String> obs = Observable.never();
          Future<String> f = obs.toFuture();
          boolean cancelled = f.cancel(true);
          assertTrue(cancelled);  // because OperationNeverComplete never does
          f.get(Long.MAX_VALUE, TimeUnit.NANOSECONDS);    // Future.get() docs require this to throw
      }
  
      @Test(expected = NoSuchElementException.class)
      public void getWithEmptyFlowable() throws Throwable {
          Observable<String> obs = Observable.empty();
          Future<String> f = obs.toFuture();
          try {
              f.get();
          }
          catch (ExecutionException e) {
              throw e.getCause();
          }
      }
  }
  