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.datastructures.ubtrees;
  
  import static org.assertj.core.api.Assertions.assertThat;
  
  import org.junit.jupiter.api.Test;
  import org.logicng.TestWithExampleFormulas;
  import org.logicng.formulas.Literal;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.SortedSet;
  import java.util.TreeSet;
  
  /**
   * Unit Tests for the class {@link UBNode}.
   * @version 2.0.0
   * @since 2.0.0
   */
  public class UBNodeTest extends TestWithExampleFormulas {
  
      private final UBNode<Integer> node1;
      private final UBNode<String> node2;
  
      public UBNodeTest() {
          this.node1 = new UBNode<>(1);
          this.node2 = new UBNode<>("String");
      }
  
      @Test
      public void testHashCode() {
          assertThat(this.node1.hashCode()).isEqualTo(this.node1.hashCode());
          assertThat(this.node1.hashCode()).isEqualTo(new UBNode<>(1).hashCode());
      }
  
      @Test
      public void testEquals() {
          assertThat(this.node1.hashCode()).isEqualTo(this.node1.hashCode());
          final List<SortedSet<Literal>> primeImplicants = new ArrayList<>();
          primeImplicants.add(new TreeSet<>(Arrays.asList(this.A, this.NB)));
          primeImplicants.add(new TreeSet<>(Arrays.asList(this.A, this.C)));
          final List<SortedSet<Literal>> primeImplicates = new ArrayList<>();
          primeImplicates.add(new TreeSet<>(Arrays.asList(this.A, this.NB)));
          assertThat(this.node1.equals(this.node1)).isTrue();
          assertThat(this.node1.equals(new UBNode<>(1))).isTrue();
          assertThat(this.node1.equals(this.node2)).isFalse();
          assertThat(this.node2.equals(this.node1)).isFalse();
          assertThat(this.node1.equals(null)).isFalse();
      }
  
      @Test
      public void testToString() {
          assertThat(this.node1.toString()).isEqualTo(
                  "UBNode{" +
                          "element=1" +
                          ", children={}" +
                          ", set=null" +
                          '}');
      }
  }
  