code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
  //                / /___/ /_/ / /_/ / / /__/ /|  / /_/ /                 //
  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               The Next Generation Logic Library                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  //                                                                       //
  //  Copyright 2015-20xx Christoph Zengler                                //
  //                                                                       //
  //  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 org.logicng.util;
  
  import static org.assertj.core.api.Assertions.assertThat;
  
  import org.junit.jupiter.api.Test;
  
  /**
   * Unit tests for {@link Pair}.
   * @version 2.0.0
   * @since 1.0
   */
  public class PairTest {
  
      private final Pair<String, Integer> pair1 = new Pair<>("abc", 12);
      private final Pair<String, Integer> pair2 = new Pair<>("cde", 12);
      private final Pair<String, Integer> pair3 = new Pair<>("cde", 42);
  
      @Test
      public void testGetters() {
          assertThat(this.pair1.first()).isEqualTo("abc");
          assertThat(this.pair2.first()).isEqualTo("cde");
          assertThat(this.pair3.first()).isEqualTo("cde");
          assertThat((int) this.pair1.second()).isEqualTo(12);
          assertThat((int) this.pair2.second()).isEqualTo(12);
          assertThat((int) this.pair3.second()).isEqualTo(42);
      }
  
      @Test
      public void testHashCode() {
          assertThat(this.pair1.hashCode()).isEqualTo(this.pair1.hashCode());
          assertThat(new Pair<>("abc", 12).hashCode()).isEqualTo(this.pair1.hashCode());
      }
  
      @Test
      public void testEquals() {
          assertThat(this.pair1.equals(this.pair1)).isTrue();
          assertThat(this.pair1.equals(new Pair<>("abc", 12))).isTrue();
          assertThat(this.pair1.equals(this.pair2)).isFalse();
          assertThat(this.pair2.equals(this.pair3)).isFalse();
          assertThat(this.pair1.equals(this.pair3)).isFalse();
          assertThat(this.pair1.equals("String")).isFalse();
          assertThat(this.pair1.equals(null)).isFalse();
      }
  
      @Test
      public void testToString() {
          assertThat(this.pair1.toString()).isEqualTo("<abc, 12>");
          assertThat(this.pair2.toString()).isEqualTo("<cde, 12>");
          assertThat(this.pair3.toString()).isEqualTo("<cde, 42>");
      }
  
  }
  