content: /*
   * Copyright 2015, 2024 StreamEx 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 one.util.streamex;
  
  import org.junit.Test;
  
  import java.util.AbstractMap.SimpleEntry;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Map;
  import java.util.Spliterator;
  
  import static one.util.streamex.TestHelpers.checkSpliterator;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertTrue;
  
  /**
   * @author Tagir Valeev
   */
  public class PairPermutationSpliteratorTest {
      @Test
      public void testSqrt() {
          for (int rev = 0; rev < 1000; rev++) {
              int row = (int) (Math.sqrt(8 * rev + 1) - 1) / 2;
              int row2 = PairPermutationSpliterator.isqrt(rev);
              assertEquals(row, row2);
          }
          for (int row : new int[]{1_000_000_000, 2_000_000_000, Integer.MAX_VALUE - 1, Integer.MAX_VALUE}) {
              assertEquals(row, PairPermutationSpliterator.isqrt(row * (row + 1L) / 2));
              assertEquals(row - 1, PairPermutationSpliterator.isqrt(row * (row + 1L) / 2 - 1));
          }
      }
  
      @Test
      public void testCharacteristics() {
          PairPermutationSpliterator<Integer, Integer> spltr = new PairPermutationSpliterator<>(Arrays.asList(1, 2, 3),
                  Integer::sum);
          assertTrue(spltr.hasCharacteristics(Spliterator.ORDERED));
          assertTrue(spltr.hasCharacteristics(Spliterator.SIZED));
          assertTrue(spltr.hasCharacteristics(Spliterator.SUBSIZED));
          assertEquals(3, spltr.getExactSizeIfKnown());
      }
  
      @Test
      public void testSpliterator() {
          for (int i : IntStreamEx.rangeClosed(2, 13).boxed()) {
              List<Integer> input = IntStreamEx.range(i).boxed().toList();
              List<Map.Entry<Integer, Integer>> expected = IntStreamEx.range(i)
                      .<Map.Entry<Integer, Integer>>flatMapToObj(
                              a -> IntStreamEx.range(a + 1, i).mapToObj(b -> new SimpleEntry<>(a, b))).toList();
              checkSpliterator("#" + i, expected, () -> new PairPermutationSpliterator<>(input, SimpleEntry::new));
          }
      }
  }
  