/*
    * 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.keyvalue;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertSame;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.junit.jupiter.api.Test;
  
  /**
   * Abstract tests that can be extended to test any Map.Entry implementation.
   * Subclasses must implement {@link #makeMapEntry(Object, Object)} to return
   * a new Map.Entry of the type being tested. Subclasses must also implement
   * {@link #testConstructors()} to test the constructors of the Map.Entry
   * type being tested.
   */
  public abstract class AbstractMapEntryTest<K, V> {
  
      protected final String key = "name";
      protected final String value = "duke";
  
      /**
       * Makes a Map.Entry of a type that's known to work correctly.
       */
      public Map.Entry<K, V> makeKnownMapEntry() {
          return makeKnownMapEntry(null, null);
      }
  
      /**
       * Makes a Map.Entry of a type that's known to work correctly.
       */
      public Map.Entry<K, V> makeKnownMapEntry(final K key, final V value) {
          final Map<K, V> map = new HashMap<>(1);
          map.put(key, value);
          return map.entrySet().iterator().next();
      }
  
      /**
       * Make an instance of Map.Entry with the default (null) key and value.
       * This implementation simply calls {@link #makeMapEntry(Object, Object)}
       * with null for key and value. Subclasses can override this method if desired.
       */
      public Map.Entry<K, V> makeMapEntry() {
          return makeMapEntry(null, null);
      }
  
      /**
       * Make an instance of Map.Entry with the specified key and value.
       * Subclasses should override this method to return a Map.Entry
       * of the type being tested.
       */
      public abstract Map.Entry<K, V> makeMapEntry(K key, V value);
  
      @Test
      @SuppressWarnings("unchecked")
      public void testAccessorsAndMutators() {
          Map.Entry<K, V> entry = makeMapEntry((K) key, (V) value);
  
          assertSame(key, entry.getKey());
  
          entry.setValue((V) value);
          assertSame(value, entry.getValue());
  
          // check that null doesn't do anything funny
          entry = makeMapEntry(null, null);
          assertNull(entry.getKey());
  
          entry.setValue(null);
          assertNull(entry.getValue());
      }
  
      /**
       * Subclasses should provide tests for their constructors.
       */
      public abstract void testConstructors();
  
      @Test
      @SuppressWarnings("unchecked")
      public void testEqualsAndHashCode() {
         // 1. test with object data
         Map.Entry<K, V> e1 = makeMapEntry((K) key, (V) value);
         Map.Entry<K, V> e2 = makeKnownMapEntry((K) key, (V) value);
 
         assertEquals(e1, e1);
         assertEquals(e2, e1);
         assertEquals(e1, e2);
         assertEquals(e1.hashCode(), e2.hashCode());
 
         // 2. test with nulls
         e1 = makeMapEntry();
         e2 = makeKnownMapEntry();
 
         assertEquals(e1, e1);
         assertEquals(e2, e1);
         assertEquals(e1, e2);
         assertEquals(e1.hashCode(), e2.hashCode());
     }
 
     /**
      * Subclasses should override this method to test the
      * desired behavior of the class with respect to
      * handling of self-references.
      */
 
     @Test
     @SuppressWarnings("unchecked")
     public void testSelfReferenceHandling() {
         // test that #setValue does not permit
         //  the MapEntry to contain itself (and thus cause infinite recursion
         //  in #hashCode and #toString)
 
         final Map.Entry<K, V> entry = makeMapEntry();
 
         assertThrows(IllegalArgumentException.class, () -> entry.setValue((V) entry));
 
         // check that the KVP's state has not changed
         assertTrue(entry.getKey() == null && entry.getValue() == null);
     }
 
     @Test
     @SuppressWarnings("unchecked")
     public void testToString() {
         Map.Entry<K, V> entry = makeMapEntry((K) key, (V) value);
         assertEquals(entry.toString(), entry.getKey() + "=" + entry.getValue());
 
         // test with nulls
         entry = makeMapEntry();
         assertEquals(entry.toString(), entry.getKey() + "=" + entry.getValue());
     }
 
 }