content: package com.annimon.stream.intstreamtests;
  
  import com.annimon.stream.Functions;
  import com.annimon.stream.IntStream;
  import com.annimon.stream.OptionalInt;
  import org.junit.Test;
  import static com.annimon.stream.test.hamcrest.OptionalIntMatcher.hasValue;
  import static com.annimon.stream.test.hamcrest.OptionalIntMatcher.isEmpty;
  import static org.hamcrest.MatcherAssert.assertThat;
  
  public final class FindSingleTest {
  
      @Test
      public void testFindSingleOnEmptyStream() {
          assertThat(IntStream.empty().findSingle(), isEmpty());
      }
  
      @Test
      public void testFindSingleOnOneElementStream() {
          OptionalInt result = IntStream.of(42).findSingle();
  
          assertThat(result, hasValue(42));
      }
  
      @Test(expected = IllegalStateException.class)
      public void testFindSingleOnMoreElementsStream() {
          IntStream.rangeClosed(1, 2).findSingle();
      }
  
      @Test
      public void testFindSingleAfterFilteringToEmptyStream() {
          OptionalInt result = IntStream.range(1, 5)
                  .filter(Functions.remainderInt(6))
                  .findSingle();
  
          assertThat(result, isEmpty());
      }
  
      @Test
      public void testFindSingleAfterFilteringToOneElementStream() {
          OptionalInt result = IntStream.range(1, 10)
                  .filter(Functions.remainderInt(6))
                  .findSingle();
  
          assertThat(result, hasValue(6));
      }
  
      @Test(expected = IllegalStateException.class)
      public void testFindSingleAfterFilteringToMoreElementStream() {
          IntStream.range(1, 100)
                  .filter(Functions.remainderInt(6))
                  .findSingle();
      }
  }
  