content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.kafka.common.utils;
  
  import org.apache.kafka.common.utils.ImplicitLinkedHashCollectionTest.TestElement;
  
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.Timeout;
  
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.Random;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertSame;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assertions.fail;
  
  /**
   * A unit test for ImplicitLinkedHashMultiCollection.
   */
  @Timeout(120)
  public class ImplicitLinkedHashMultiCollectionTest {
  
      @Test
      public void testNullForbidden() {
          ImplicitLinkedHashMultiCollection<TestElement> multiSet = new ImplicitLinkedHashMultiCollection<>();
          assertFalse(multiSet.add(null));
      }
  
      @Test
      public void testFindFindAllContainsRemoveOnEmptyCollection() {
          ImplicitLinkedHashMultiCollection<TestElement> coll = new ImplicitLinkedHashMultiCollection<>();
          assertNull(coll.find(new TestElement(2)));
          assertFalse(coll.contains(new TestElement(2)));
          assertFalse(coll.remove(new TestElement(2)));
          assertTrue(coll.findAll(new TestElement(2)).isEmpty());
      }
  
      @Test
      public void testInsertDelete() {
          ImplicitLinkedHashMultiCollection<TestElement> multiSet = new ImplicitLinkedHashMultiCollection<>(100);
          TestElement e1 = new TestElement(1);
          TestElement e2 = new TestElement(1);
          TestElement e3 = new TestElement(2);
          multiSet.mustAdd(e1);
          multiSet.mustAdd(e2);
          multiSet.mustAdd(e3);
          assertFalse(multiSet.add(e3));
          assertEquals(3, multiSet.size());
          expectExactTraversal(multiSet.findAll(e1).iterator(), e1, e2);
          expectExactTraversal(multiSet.findAll(e3).iterator(), e3);
          multiSet.remove(e2);
          expectExactTraversal(multiSet.findAll(e1).iterator(), e1);
          assertTrue(multiSet.contains(e2));
      }
  
      @Test
      public void testTraversal() {
          ImplicitLinkedHashMultiCollection<TestElement> multiSet = new ImplicitLinkedHashMultiCollection<>();
          expectExactTraversal(multiSet.iterator());
          TestElement e1 = new TestElement(1);
          TestElement e2 = new TestElement(1);
          TestElement e3 = new TestElement(2);
          assertTrue(multiSet.add(e1));
          assertTrue(multiSet.add(e2));
          assertTrue(multiSet.add(e3));
          expectExactTraversal(multiSet.iterator(), e1, e2, e3);
          assertTrue(multiSet.remove(e2));
          expectExactTraversal(multiSet.iterator(), e1, e3);
          assertTrue(multiSet.remove(e1));
          expectExactTraversal(multiSet.iterator(), e3);
      }
  
      static void expectExactTraversal(Iterator<TestElement> iterator, TestElement... sequence) {
          int i = 0;
          while (iterator.hasNext()) {
              TestElement element = iterator.next();
              assertTrue(i < sequence.length, "Iterator yieled " + (i + 1) + " elements, but only " +
                  sequence.length + " were expected.");
              if (sequence[i] != element) {
                  fail("Iterator value number " + (i + 1) + " was incorrect.");
              }
              i = i + 1;
          }
          assertEquals(sequence.length, i, "Iterator yieled " + (i + 1) + " elements, but " +
                  sequence.length + " were expected.");
      }
  
      @Test
      public void testEnlargement() {
          ImplicitLinkedHashMultiCollection<TestElement> multiSet = new ImplicitLinkedHashMultiCollection<>(5);
          assertEquals(11, multiSet.numSlots());
          TestElement[] testElements = {
              new TestElement(100),
              new TestElement(101),
              new TestElement(102),
              new TestElement(100),
              new TestElement(101),
              new TestElement(105)
          };
          for (TestElement testElement : testElements) {
              assertTrue(multiSet.add(testElement));
              assertFalse(multiSet.add(testElement));
          }
          assertEquals(23, multiSet.numSlots());
          assertEquals(testElements.length, multiSet.size());
          expectExactTraversal(multiSet.iterator(), testElements);
          multiSet.remove(testElements[1]);
          assertEquals(23, multiSet.numSlots());
          assertEquals(5, multiSet.size());
          expectExactTraversal(multiSet.iterator(),
              testElements[0], testElements[2], testElements[3], testElements[4], testElements[5]);
      }
  
      @Test
      public void testManyInsertsAndDeletes() {
          Random random = new Random(123);
          LinkedList<TestElement> existing = new LinkedList<>();
          ImplicitLinkedHashMultiCollection<TestElement> multiSet = new ImplicitLinkedHashMultiCollection<>();
          for (int i = 0; i < 100; i++) {
              for (int j = 0; j < 4; j++) {
                  TestElement testElement = new TestElement(random.nextInt());
                  multiSet.mustAdd(testElement);
                  existing.add(testElement);
              }
              int elementToRemove = random.nextInt(multiSet.size());
              Iterator<TestElement> iter1 = multiSet.iterator();
              Iterator<TestElement> iter2 = existing.iterator();
              for (int j = 0; j <= elementToRemove; j++) {
                  iter1.next();
                  iter2.next();
              }
              iter1.remove();
              iter2.remove();
              expectTraversal(multiSet.iterator(), existing.iterator());
          }
      }
  
      void expectTraversal(Iterator<TestElement> iter, Iterator<TestElement> expectedIter) {
          int i = 0;
          while (iter.hasNext()) {
              TestElement element = iter.next();
              assertTrue(expectedIter.hasNext(),
                  "Iterator yieled " + (i + 1) + " elements, but only " + i + " were expected.");
              TestElement expected = expectedIter.next();
              assertSame(expected, element, "Iterator value number " + (i + 1) + " was incorrect.");
              i = i + 1;
          }
          assertFalse(expectedIter.hasNext(),
              "Iterator yieled " + i + " elements, but at least " + (i + 1) + " were expected.");
      }
  }
  