/*
    * 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.commons.collections4;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  import java.util.Arrays;
  
  import org.apache.commons.collections4.multiset.HashMultiSet;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests for MultiSetUtils.
   */
  public class MultiSetUtilsTest {
  
      private String[] fullArray;
      private MultiSet<String> multiSet;
  
      @BeforeEach
      public void setUp() {
          fullArray = new String[]{
              "a", "a", "b", "c", "d", "d", "d"
          };
          multiSet = new HashMultiSet<>(Arrays.asList(fullArray));
      }
  
      /**
       * Tests {@link MultiSetUtils#emptyMultiSet()}.
       */
      @Test
      public void testEmptyMultiSet() {
          final MultiSet<Integer> empty = MultiSetUtils.emptyMultiSet();
          assertEquals(0, empty.size());
  
          assertThrows(UnsupportedOperationException.class, () -> empty.add(55),
                  "Empty multi set must be read-only");
      }
  
      /**
       * Tests {@link MultiSetUtils#predicatedMultiSet(org.apache.commons.collections4.MultiSet, org.apache.commons.collections4.Predicate)}.
       */
      @Test
      public void testPredicatedMultiSet() {
          final Predicate<String> predicate = object -> object.length() == 1;
          final MultiSet<String> predicated = MultiSetUtils.predicatedMultiSet(multiSet, predicate);
          assertEquals(multiSet.size(), predicated.size());
          assertEquals(multiSet.getCount("a"), predicated.getCount("a"));
  
          assertThrows(NullPointerException.class, () -> MultiSetUtils.predicatedMultiSet(null, predicate),
                  "Expecting NPE");
  
          assertThrows(NullPointerException.class, () -> MultiSetUtils.predicatedMultiSet(multiSet, null),
                  "Expecting NPE");
  
          assertThrows(IllegalArgumentException.class, () -> MultiSetUtils.predicatedMultiSet(multiSet, object -> object.equals("a")),
                  "Predicate is violated for all elements not being 'a'");
      }
  
      /**
       * Tests {@link MultiSetUtils#unmodifiableMultiSet(org.apache.commons.collections4.MultiSet) ()}.
       */
      @Test
      public void testSynchronizedMultiSet() {
          final MultiSet<String> synced = MultiSetUtils.synchronizedMultiSet(multiSet);
          assertEquals(multiSet, synced);
          synced.add("a"); // ensure adding works
      }
  
      /**
       * Tests {@link MultiSetUtils#unmodifiableMultiSet(org.apache.commons.collections4.MultiSet) ()}.
       */
      @Test
      public void testUnmodifiableMultiSet() {
          final MultiSet<String> unmodifiable = MultiSetUtils.unmodifiableMultiSet(multiSet);
          assertEquals(multiSet, unmodifiable);
  
          assertThrows(UnsupportedOperationException.class, () -> unmodifiable.add("a"),
                  "Empty multi set must be read-only");
  
          assertThrows(NullPointerException.class, () -> MultiSetUtils.unmodifiableMultiSet(null),
                  "Expecting NPE");
      }
 
 }