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.cardinalityconstraints;
  
  import static org.assertj.core.api.Assertions.assertThat;
  
  import org.junit.jupiter.api.Test;
  import org.logicng.LogicNGTest;
  import org.logicng.datastructures.EncodingResult;
  import org.logicng.formulas.CType;
  import org.logicng.formulas.FormulaFactory;
  import org.logicng.formulas.Variable;
  import org.logicng.solvers.MiniSat;
  import org.logicng.solvers.SATSolver;
  
  /**
   * Unit tests for the exactly-k encoders.
   * @version 2.0.0
   * @since 1.1
   */
  public class CCEXKTest implements LogicNGTest {
  
      private final CCConfig[] configs;
  
      public CCEXKTest() {
          this.configs = new CCConfig[2];
          this.configs[0] = CCConfig.builder().exkEncoding(CCConfig.EXK_ENCODER.TOTALIZER).build();
          this.configs[1] = CCConfig.builder().exkEncoding(CCConfig.EXK_ENCODER.CARDINALITY_NETWORK).build();
      }
  
      @Test
      public void testEXK() {
          final FormulaFactory f = new FormulaFactory();
          int counter = 0;
          for (final CCConfig config : this.configs) {
              f.putConfiguration(config);
              testCC(10, 1, 10, f);
              testCC(10, 2, 45, f);
              testCC(10, 3, 120, f);
              testCC(10, 4, 210, f);
              testCC(10, 5, 252, f);
              testCC(10, 6, 210, f);
              testCC(10, 7, 120, f);
              testCC(10, 8, 45, f);
              testCC(10, 9, 10, f);
              testCC(10, 10, 1, f);
              testCC(10, 12, 0, f);
              assertThat(f.newCCVariable().name()).endsWith("_" + counter++);
          }
      }
  
      private void testCC(final int numLits, final int rhs, final int expected, final FormulaFactory f) {
          final Variable[] problemLits = new Variable[numLits];
          for (int i = 0; i < numLits; i++) {
              problemLits[i] = f.variable("v" + i);
          }
          final SATSolver solver = MiniSat.miniSat(f);
          solver.add(f.cc(CType.EQ, rhs, problemLits));
          if (expected != 0) {
              assertSolverSat(solver);
          } else {
              assertSolverUnsat(solver);
          }
          assertThat(solver.enumerateAllModels(problemLits))
                  .hasSize(expected)
                  .allMatch(m -> m.positiveVariables().size() == rhs);
      }
  
      @Test
      public void testCCEXKTotalizer() {
          final FormulaFactory f = new FormulaFactory();
          final CCEXKTotalizer totalizer = new CCEXKTotalizer();
          totalizer.build(EncodingResult.resultForFormula(f), new Variable[]{f.variable("A"), f.variable("B"), f.variable("C")}, 2);
          assertThat(totalizer.incrementalData()).isNull();
          assertThat(totalizer.toString()).isEqualTo("CCEXKTotalizer");
  
          final CCEXKCardinalityNetwork cNetwork = new CCEXKCardinalityNetwork();
          cNetwork.build(EncodingResult.resultForFormula(f), new Variable[]{f.variable("A"), f.variable("B"), f.variable("C")}, 2);
          assertThat(cNetwork.incrementalData()).isNull();
          assertThat(cNetwork.toString()).isEqualTo("CCEXKCardinalityNetwork");
      }
  
      @Test
      public void testToString() {
          assertThat(this.configs[0].exkEncoder.toString()).isEqualTo("TOTALIZER");
          assertThat(this.configs[1].exkEncoder.toString()).isEqualTo("CARDINALITY_NETWORK");
  
          assertThat(CCConfig.EXK_ENCODER.values()).contains(CCConfig.EXK_ENCODER.valueOf("CARDINALITY_NETWORK"));
      }
  }
  