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.np;
  
  import static org.assertj.core.api.Assertions.assertThat;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.TreeSet;
  
  /**
   * Unit tests for {@link SetCover}.
   * @version 2.0.0
   * @since 2.0.0
   */
  public class SetCoverTest {
  
      @Test
      public void smallTest() {
          final List<Set<String>> sets = new ArrayList<>();
          sets.add(new TreeSet<>(Arrays.asList("a", "b", "c", "d", "e", "f")));
          sets.add(new TreeSet<>(Arrays.asList("e", "f", "h", "i")));
          sets.add(new TreeSet<>(Arrays.asList("a", "d", "g", "j")));
          sets.add(new TreeSet<>(Arrays.asList("b", "e", "h", "k")));
          sets.add(new TreeSet<>(Arrays.asList("c", "f", "i", "l")));
          sets.add(new TreeSet<>(Arrays.asList("j", "k", "l")));
          assertThat(SetCover.compute(sets)).containsExactlyInAnyOrder(sets.get(2), sets.get(3), sets.get(4));
      }
  
      @Test
      public void cornerCasesTest() {
          final List<Set<String>> sets = new ArrayList<>();
          assertThat(SetCover.compute(sets)).isEmpty();
          sets.add(Collections.emptySet());
          assertThat(SetCover.compute(sets)).isEmpty();
          sets.add(new HashSet<>(Collections.singletonList("A")));
          sets.add(new HashSet<>(Collections.singletonList("A")));
          sets.add(new HashSet<>(Collections.singletonList("A")));
          assertThat(SetCover.compute(sets)).hasSize(1);
          sets.add(new HashSet<>(Collections.singletonList("B")));
          assertThat(SetCover.compute(sets)).containsExactlyInAnyOrder(
                  new HashSet<>(Collections.singletonList("A")),
                  new HashSet<>(Collections.singletonList("B"))
          );
          sets.add(new HashSet<>(Arrays.asList("A", "B")));
          assertThat(SetCover.compute(sets)).hasSize(1).containsExactly(
                  new HashSet<>(Arrays.asList("A", "B"))
          );
      }
  }
  