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.single;
  
  import static org.junit.Assert.*;
  
  import java.util.Arrays;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.processors.PublishProcessor;
  import io.reactivex.rxjava3.subscribers.TestSubscriber;
  import io.reactivex.rxjava3.testsupport.TestHelper;
  
  public class SingleConcatTest extends RxJavaTest {
      @Test
      public void concatWith() {
          Single.just(1).concatWith(Single.just(2))
          .test()
          .assertResult(1, 2);
      }
  
      @Test
      public void concat2() {
          Single.concat(Single.just(1), Single.just(2))
          .test()
          .assertResult(1, 2);
      }
  
      @Test
      public void concat3() {
          Single.concat(Single.just(1), Single.just(2), Single.just(3))
          .test()
          .assertResult(1, 2, 3);
      }
  
      @Test
      public void concat4() {
          Single.concat(Single.just(1), Single.just(2), Single.just(3), Single.just(4))
          .test()
          .assertResult(1, 2, 3, 4);
      }
  
      @SuppressWarnings("unchecked")
      @Test
      public void concatArray() {
          for (int i = 1; i < 100; i++) {
              Single<Integer>[] array = new Single[i];
  
              Arrays.fill(array, Single.just(1));
  
              Single.concatArray(array)
              .to(TestHelper.<Integer>testConsumer())
              .assertSubscribed()
              .assertValueCount(i)
              .assertNoErrors()
              .assertComplete();
          }
      }
  
      @Test
      public void concatArrayEagerTest() {
          PublishProcessor<String> pp1 = PublishProcessor.create();
          PublishProcessor<String> pp2 = PublishProcessor.create();
  
          TestSubscriber<String> ts = Single.concatArrayEager(pp1.single("1"), pp2.single("2")).test();
  
          assertTrue(pp1.hasSubscribers());
          assertTrue(pp2.hasSubscribers());
  
          pp2.onComplete();
          ts.assertEmpty();
          pp1.onComplete();
  
          ts.assertResult("1", "2");
          ts.assertComplete();
      }
  
      @Test
      public void concatEagerIterableTest() {
          PublishProcessor<String> pp1 = PublishProcessor.create();
          PublishProcessor<String> pp2 = PublishProcessor.create();
  
          TestSubscriber<String> ts = Single.concatEager(Arrays.asList(pp1.single("2"), pp2.single("1"))).test();
  
          assertTrue(pp1.hasSubscribers());
          assertTrue(pp2.hasSubscribers());
  
          pp2.onComplete();
          ts.assertEmpty();
          pp1.onComplete();
  
          ts.assertResult("2", "1");
          ts.assertComplete();
      }
  
      @Test
      public void concatEagerPublisherTest() {
          PublishProcessor<String> pp1 = PublishProcessor.create();
          PublishProcessor<String> pp2 = PublishProcessor.create();
  
          TestSubscriber<String> ts = Single.concatEager(Flowable.just(pp1.single("1"), pp2.single("2"))).test();
  
          assertTrue(pp1.hasSubscribers());
          assertTrue(pp2.hasSubscribers());
  
          pp2.onComplete();
          ts.assertEmpty();
          pp1.onComplete();
  
          ts.assertResult("1", "2");
          ts.assertComplete();
      }
  
      @SuppressWarnings("unchecked")
      @Test
      public void concatObservable() {
          for (int i = 1; i < 100; i++) {
              Single<Integer>[] array = new Single[i];
  
              Arrays.fill(array, Single.just(1));
  
              Single.concat(Observable.fromArray(array))
              .to(TestHelper.<Integer>testConsumer())
              .assertSubscribed()
              .assertValueCount(i)
              .assertNoErrors()
              .assertComplete();
          }
      }
  
      @Test
      public void noSubsequentSubscription() {
          final int[] calls = { 0 };
  
          Single<Integer> source = Single.create(new SingleOnSubscribe<Integer>() {
              @Override
              public void subscribe(SingleEmitter<Integer> s) throws Exception {
                  calls[0]++;
                  s.onSuccess(1);
              }
          });
  
          Single.concatArray(source, source).firstElement()
          .test()
          .assertResult(1);
  
          assertEquals(1, calls[0]);
      }
  
      @Test
      public void noSubsequentSubscriptionIterable() {
          final int[] calls = { 0 };
  
          Single<Integer> source = Single.create(new SingleOnSubscribe<Integer>() {
              @Override
              public void subscribe(SingleEmitter<Integer> s) throws Exception {
                  calls[0]++;
                  s.onSuccess(1);
              }
          });
  
          Single.concat(Arrays.asList(source, source)).firstElement()
          .test()
          .assertResult(1);
  
          assertEquals(1, calls[0]);
      }
  }
  