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.assertEquals;
  import static org.mockito.ArgumentMatchers.any;
  import static org.mockito.Mockito.*;
  
  import java.util.Arrays;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.junit.Test;
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.subscribers.TestSubscriber;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class FlowableSkipTest extends RxJavaTest {
  
      @Test(expected = IllegalArgumentException.class)
      public void skipNegativeElements() {
  
          Flowable<String> skip = Flowable.just("one", "two", "three").skip(-99);
  
          Subscriber<String> subscriber = TestHelper.mockSubscriber();
          skip.subscribe(subscriber);
          verify(subscriber, times(1)).onNext("one");
          verify(subscriber, times(1)).onNext("two");
          verify(subscriber, times(1)).onNext("three");
          verify(subscriber, never()).onError(any(Throwable.class));
          verify(subscriber, times(1)).onComplete();
      }
  
      @Test
      public void skipZeroElements() {
  
          Flowable<String> skip = Flowable.just("one", "two", "three").skip(0);
  
          Subscriber<String> subscriber = TestHelper.mockSubscriber();
          skip.subscribe(subscriber);
          verify(subscriber, times(1)).onNext("one");
          verify(subscriber, times(1)).onNext("two");
          verify(subscriber, times(1)).onNext("three");
          verify(subscriber, never()).onError(any(Throwable.class));
          verify(subscriber, times(1)).onComplete();
      }
  
      @Test
      public void skipOneElement() {
  
          Flowable<String> skip = Flowable.just("one", "two", "three").skip(1);
  
          Subscriber<String> subscriber = TestHelper.mockSubscriber();
          skip.subscribe(subscriber);
          verify(subscriber, never()).onNext("one");
          verify(subscriber, times(1)).onNext("two");
          verify(subscriber, times(1)).onNext("three");
          verify(subscriber, never()).onError(any(Throwable.class));
          verify(subscriber, times(1)).onComplete();
      }
  
      @Test
      public void skipTwoElements() {
  
          Flowable<String> skip = Flowable.just("one", "two", "three").skip(2);
  
          Subscriber<String> subscriber = TestHelper.mockSubscriber();
          skip.subscribe(subscriber);
          verify(subscriber, never()).onNext("one");
          verify(subscriber, never()).onNext("two");
          verify(subscriber, times(1)).onNext("three");
          verify(subscriber, never()).onError(any(Throwable.class));
          verify(subscriber, times(1)).onComplete();
      }
  
      @Test
      public void skipEmptyStream() {
  
          Flowable<String> w = Flowable.empty();
          Flowable<String> skip = w.skip(1);
  
          Subscriber<String> subscriber = TestHelper.mockSubscriber();
          skip.subscribe(subscriber);
          verify(subscriber, never()).onNext(any(String.class));
          verify(subscriber, never()).onError(any(Throwable.class));
          verify(subscriber, times(1)).onComplete();
      }
  
      @Test
      public void skipMultipleObservers() {
  
          Flowable<String> skip = Flowable.just("one", "two", "three")
                  .skip(2);
  
          Subscriber<String> subscriber1 = TestHelper.mockSubscriber();
          skip.subscribe(subscriber1);
  
          Subscriber<String> subscriber2 = TestHelper.mockSubscriber();
          skip.subscribe(subscriber2);
  
          verify(subscriber1, times(1)).onNext(any(String.class));
          verify(subscriber1, never()).onError(any(Throwable.class));
          verify(subscriber1, times(1)).onComplete();
  
          verify(subscriber2, times(1)).onNext(any(String.class));
          verify(subscriber2, never()).onError(any(Throwable.class));
          verify(subscriber2, times(1)).onComplete();
      }
  
      @Test
      public void skipError() {
  
          Exception e = new Exception();
  
          Flowable<String> ok = Flowable.just("one");
          Flowable<String> error = Flowable.error(e);
  
          Flowable<String> skip = Flowable.concat(ok, error).skip(100);
  
          Subscriber<String> subscriber = TestHelper.mockSubscriber();
          skip.subscribe(subscriber);
  
          verify(subscriber, never()).onNext(any(String.class));
          verify(subscriber, times(1)).onError(e);
          verify(subscriber, never()).onComplete();
  
      }
  
      @Test
      public void backpressureMultipleSmallAsyncRequests() throws InterruptedException {
          final AtomicLong requests = new AtomicLong(0);
          TestSubscriber<Long> ts = new TestSubscriber<>(0L);
          Flowable.interval(100, TimeUnit.MILLISECONDS)
                  .doOnRequest(new LongConsumer() {
                      @Override
                      public void accept(long n) {
                          requests.addAndGet(n);
                      }
                  }).skip(4).subscribe(ts);
          Thread.sleep(100);
          ts.request(1);
          ts.request(1);
          Thread.sleep(100);
          ts.cancel();
          ts.assertNoErrors();
          assertEquals(6, requests.get());
      }
  
      @Test
      public void requestOverflowDoesNotOccur() {
          TestSubscriberEx<Integer> ts = new TestSubscriberEx<>(Long.MAX_VALUE - 1);
          Flowable.range(1, 10).skip(5).subscribe(ts);
          ts.assertTerminated();
          ts.assertComplete();
          ts.assertNoErrors();
          assertEquals(Arrays.asList(6, 7, 8, 9, 10), ts.values());
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Flowable.just(1).skip(2));
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeFlowable(new Function<Flowable<Object>, Flowable<Object>>() {
              @Override
              public Flowable<Object> apply(Flowable<Object> f)
                      throws Exception {
                  return f.skip(1);
              }
          });
      }
  
  }
  