content: package com.annimon.stream.streamtests;
  
  import com.annimon.stream.CustomOperators;
  import com.annimon.stream.Stream;
  import com.annimon.stream.function.Consumer;
  import com.annimon.stream.function.Function;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import org.junit.Test;
  import static com.annimon.stream.test.hamcrest.StreamMatcher.assertElements;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.contains;
  import static org.junit.Assert.assertEquals;
  
  public final class CustomTest {
  
      @Test(expected = NullPointerException.class)
      public void testCustomNull() {
          Stream.empty().custom(null);
      }
  
      @Test
      public void testCustomIntermediateOperator_Reverse() {
          Stream.range(0, 10)
                  .custom(new CustomOperators.Reverse<Integer>())
                  .custom(assertElements(contains(
                        9, 8, 7, 6, 5, 4, 3, 2, 1, 0
                  )));
      }
  
      @Test
      public void testCustomIntermediateOperator_SkipAndLimit() {
          Stream.range(0, 10)
                  .custom(new CustomOperators.SkipAndLimit<Integer>(5, 2))
                  .custom(assertElements(contains(
                          5, 6
                  )));
      }
  
      @Test
      public void testCustomIntermediateOperator_FlatMapAndCast() {
          List<List> lists = new ArrayList<List>();
          for (char ch = 'a'; ch <= 'f'; ch++) {
              lists.add( new ArrayList<Character>(Arrays.asList(ch)) );
          }
          Stream.of(lists)
                  .custom(new CustomOperators.FlatMap<List, Object>(new Function<List, Stream<Object>>() {
                      @SuppressWarnings("unchecked")
                      @Override
                      public Stream<Object> apply(List value) {
                          return Stream.of(value);
                      }
                  }))
                  .custom(new CustomOperators.Cast<Object, Character>(Character.class))
                  .custom(assertElements(contains('a', 'b', 'c', 'd', 'e', 'f')));
      }
  
      @Test
      public void testCustomTerminalOperator_Sum() {
          int sum = Stream.of(1, 2, 3, 4, 5)
                  .custom(new CustomOperators.Sum());
          assertEquals(15, sum);
      }
  
      @Test
      public void testCustomTerminalOperator_ForEach() {
          final List<Integer> list = new ArrayList<Integer>();
          Stream.range(0, 10)
                  .custom(new CustomOperators.ForEach<Integer>(new Consumer<Integer>() {
                      @Override
                      public void accept(Integer t) {
                          list.add(t);
                      }
                  }));
  
          assertThat(list, contains(0, 1, 2, 3, 4, 5, 6, 7, 8, 9));
      }
  }
  